MSC-Elective-I-Track-B-Cyber-and-Information-Security-Network-Security-munotes

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COMPUTER SECURITY
Unit Structure :
1.0 Objectives
1.1 Introduction
1.2 What is security
1.3 Principle of security
1.4 Attacks
1.4.1 Malicious program
1.4.2 Nonmalicious program
1.5 Types of Computer Criminals
1.6 Summary
1.7 References for readin g
1.0 OBJECTIVES
1. To understand the basics of security
2. To understand the attacks and types of computer criminals
3. To understand why security is needed.
4. To understand the necessity to maintain a safe network.

1.1 INTRODUCTION
Computer security basically is the protection of computer systems and
information from harm, theft, and unauthorized use . It is the process of
preventing and detecting unauthorized use of your computer system. There
are many types of computer security which is used to protect the
valuab leorganizational information. Security is concerned with the
protection of systems, networks, applications, and information. In some
cases, it is also called electronic information security or information
technology security. Every organisation willingly p erform audits of
security to check the loopwholes of the computer systems and used to
restrict other outside devices usage in organisation and related ports or
services are restricted by their security experts to protect the information
of organisation.
There are different types of computer security such as application security,
network security, internet security, data security, information security and
end user security as shown in figure. munotes.in

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2 Fig 1.1.1 : Types of security
1. Application Security
Applicatio n security is the adding security features within applications to
prevent from attacks. The attacks can be SQL injection, DoS
attacks.Firewall, antivirus , etc are security tools which can help to prevent
from attacks.
Web Application Threats
Fig 1.1.2: Web Application Threats
Here are the most common categories of application threat s related to
software or application, which are given bellows:
A. Input validation
Input validation or data validation is the process of correct testing of any
input that is prov ide by users. It is difficult to detect a malicious user who
is trying to attack the software and applications. So, it should check and
validate all input data which will enter into a system.
Following figures shows some of vulnerabilities that could be s olved just
by validating input.
Fig 1.1.3: Input Validation
B. Authorization
It is nothing but user priviladgemechanism such as computer programs,
files, services, data, etc.
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3 C. Session management
Session management is a process used by the web container t o securing
multiple requests to a service from the same user or entity. In short track
the frequency of visits to an application and movement within the site.
There are two types of session management: one is cookie -based and
another one is URL rewriting.
D. Parameter tampering
Parameter tampering is a technique which malicious hackers attempt to
compromise an application through manipulating parameters in
the URL string.
It is a simple attack targeting the application business logic in order to
modify appl ication data, such as user credentials and permissions, price
and quantity of products.
For example, a shopping site uses hidden fields to refer to its items, as
follows:

Here, an attacker can m odify or alter the “ value ” information of a specific
item, thus lowering its cost.
2. Information Security
Information security (IS) is a types of computer security which refers to
the process and methodology to protect the confidentiality , integrity
and availability of computer system from unauthorized access, use,
modification and destruction.
Information security focuses on the CIA triad model, which ensure
confidentiality , integrity , and availability of data, without affecting
organization producti vity.
3. Network Security
Network security is other types of computer security which process of
preventing and protecting against unauthorized intrusion into computer
networks. It is a set of rules and configurations which designed to protect
the confiden tiality, integrity and accessibility of computer networks
system and information using both software and hardware technologies.
Network Security Methods
There are different components or methods to improve network security.
Here, we have mentioned the most common network security components.
 Antivirus Software
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4  Email Security
 Firewalls
 Web Security
 Wireless Security
 Network Access Control (NAC)
4. Endpoint Security
Human error is a major weak point which is easily exploited by cyber
criminals . End users are becoming the largest security risk in any
organizations. However, end user has no fault of their own, and mostly
due to a lack of awareness and ICT policy. They can unintentional open
the virtual gates to cyber attackers.
That’s why comprehensive security policies, procedures and protocols
have to be understood in depth by users who accessing the sensitive
information. It is better to provide security awareness training program to
them and should cover the following topics:
 Cyber security and its importance
 Phishing and Social Engineering attack
 Password creation and usages
 Device Security
 Physical Security
5. Internet Security
Internet security is the important types of computer se curity which has
defined as a process to create set of rules and actions to protect computers
system that are connected to the Internet. It is a branch of computer
security that deals specifically with internet -based threats such as:
A. Hacking
A Hacker is a person who finds weakness and exploits the vulnerability in
computer systems or network to gain access. Hacking refers to activities
that exploit a computer system or a network in order to gain unauthorized
access or control over systems for illegal pur pose.
B. Computer Viruses
A computer virus is a software program that can spread from one
computer system to another computer without the user’s knowledge and
performs malicious actions. It has capability to corrupt or damage data,
destroy files, format ha rd drives or make disks unreadable.
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5 There are different types of computer viruses which are as follows:
 Boot Sector Virus
 Direct Action Virus
 Resident Virus
 Macro Virus
 Multipartite Virus
 File Infector Virus
 Browser Hijacker
 Polymorphic Virus
 Web Scriptin g Virus
A computer virus may spread on your computer and other devices as the
following ways:
 Downloads Software Or Files
 E-Mail Attachments
 Phishing Emails
 External Devices
 Online Advertisements
 Click On Malicious File
 Infected Website
 Copying Data From I nfected Computer
 Unsolicited E -Mail
 Social Media Scam Links
C. Denial -of-Service Attacks
It is an attack that shut down a system and making it inaccessible to the
users. It occurs when an attacker prevents legitimate users from accessing
specific computer systems, devices or other resources and flooding a
target system.
D. Malware
Malware is short for “ malicious software ” that typically consists
of software program or code. It is developed by cyber attackers which are
designed to extensive damage to data an d systems.
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6 There are different types of malware such as
 Computerviruses
 Spyware
 Ransomware
 Worms
 Trojan horses
Any type of malicious code.
1.2 WHAT IS SECURITY [ 1]
Security for information technology (IT) refers to the methods, tools and
personnel used to defend an organization's digital assets. The goal of IT
security is to protect these assets, devices and services from being
interrupted, whipped or broken by unauthorized users. These threats can
be external or internal and malicious or accidental.
An effective security strategy uses a range of approaches to minimize
vulnerabilities and target many types of cyberthreats. Detection,
prevention and response to security threats involve the use of security
policies, software tools and IT services.
1.3 PRINC IPLE OF SECURITY [ 2]
Below figure shows the security principles.

Fig 1.3.1: Principles of security
1. Confidentiality
The confidentiality principle of security states that only their intended
sender and receiver should be able to access messages, if an u nauthorized
person gets access to this message then the confidentiality gets
compromised. For example, suppose user X wants to send a message to
user Y, and X does not want some else to get access to this message, or if
it gets access, he/she does not come to know about the details. But if user
Z somehow gets access to this secret message, which is not desired, then munotes.in

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7 the purpose of this confidentiality gets fail. This leads to the interception.
i.e. if user Z access the secret message or email sent by user X to Y
without permission of X and Y, then it is called an interception.
Interception causes loss of message confidentiality.
2. Authentication
The authentication principle of security establishes proof of identity, it
ensures that the origin of a document or electronic message is correctly
identified. For example suppose user Z sends a message to user Y,
however, the trouble is that user Z posed as user X while sending a
message to user Y. How user Y would knows that message comes from Z,
not X. This leads to the fabrication attack. For example
The attacker can act as user X and sends fund transfer request( from X’
account to attacker account) to a bank, and the bank will transfer the
amount as requested from X’s account to attacker, as banks think fund
transfer request comes from user X. Fabrication is possible in absence of
proper authentication mechanism.
3. Integrity
The integrity principle of security states that the message should not be
altered. In other words, we can say that, when the content of the message
changes after the sender sends it, but before it reaches the intended
receiver, we can say that integrity of the message is lost. For example,
suppose user X sends a message to User Y, and attacker Z somehow gets
access to this message during trans mission and changes the content of the
message and then sends it to user Y. User Y and User X does not have any
knowledge that the content of the message was changed after user X send
it to Y. This leads to a modification. Modification causes loss of messa ge
integrity.
4. Non -repudiation
Non-repudiation principle of security does not allow the sender of a
message to refute the claim of not sending that message. There are some
situations where the user sends a message and later on refuses that he/she
had sen t that message. For example, user X sends requests to the bank for
fund transfer over the internet. After the bank performs fund transfer based
on user X request, User X cannot claim that he/she never sent the fund
transfer request to the bank. This princi ple of security defeats such
possibilities of denying something after having done it.
5. Access control
Access control principles of security determine who should be able to
access what. i.e. we can specify that what users can access which
functions, for e xample, we can specify that user X can view the database
record but cannot update them, but user Y can access both, can view
record, and can update them. This principle is broadly related to two areas
– role management and rule management where role manage ment
concentrates on the user side. i.e. which user can do what and rule
management concentrate on the resources side i.e. which resource is
available. Based on this matrix is prepared, which lists the user against q munotes.in

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8 list of items they can access. The acce ss control list is a subset of the
access control matrix.
6. Availability
The availability principle of security states that resources should be
available to the authorized person at all times. For example, because of the
intentional action of another unau thorized user Z, an authorized user x
may not be able to contact server Y, this leads to an interruption attack,
interruption puts the availability of resources in danger. A real -life
example of this could be, suppose attacker or unauthorized person Z trie s
to access the FB Account of user X, as User Z does not know the
password of user X, he/she tries to log in to the X’s account using a
random password. after attempting maxim limit for the password, if it is
not correct then X’s account will be blocked, t herefore because of
unauthorized person Z, user X could not access his account.
7. Ethical and legal issues
Ethical issues in the security system are classified into the following
categories
 Privacy: It deals with the individual’s right to access the perso nal
information
 Accuracy: It deals with the responsibility of authentication, fidelity,
and accuracy of information
 Property: It deals with the owner of the information
 Accessibility: It deals with what information does an organization has
the right to col lect.

Fig 1.3.2: Types of Regulatory bodies
While dealing with legal issues, we must remember that there is a
hierarchy of regulatory bodies that govern the legality of information
security, it can be classified into the following categories
 Internationa l
 Federal
 State
 Organization

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9 1.4 ATTACKS [ 3]
A cyber attack is a set of actions performed by threat actors, who try to
gain unauthorized access, steal data or cause damage to computers,
computer networks, or other computing systems. A cyber attack can be
launched from any location. The attack can be performed by an individual
or a group using one or more tactics, techniques and procedures (TTPs).
The individuals who launch cyber attacks are usually referred to as
cybercriminals, threat actors, bad actors, or hackers. They can work alone,
in collaboration with other attackers, or as part of an organized criminal
group. They try to identify vulnerabilities —problems or we aknesses in
computer systems —and exploit them to further their goals.
Categories of attack
There are mainly two categories where attack can be classify like active
attack and passive attack.

Fig 1.4.1: Categories of Attacks
Active attack means some modi fication or some harmful changes done in
system.
passive attack means monitor the activities to create strategy for attacking.
Following table will give glance about these categories
Sr. No. Active Attack Passive Attack
1 Access information and then
do th e modification Only access information
2 System will get impacted No harm for system
3 Easier to detect attack Difficult to detect attack
4 Threat to integrity and
availability Threat to confidentiality
5 Example – Repudiation,
DOS Example – Network tr affic
analysis

Cyber Attack Statistics
The global cost of cyber attacks is expected to grow by 15% per year and
is expected to reach over $10 trillion. A growing part of this cost is
Ransomware attacks, which now cost businesses in the US $20 billion per munotes.in

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10 year.The average cost of a data breach in the US is $3.8 million. Another
alarming statistic is that public companies lose an average of 8% of their
stock value after a successful breach.
In a recent survey, 78% of respondents said they b elieve their company’s
cybersecurity measures need to be improved. As many as 43% of small
businesses do not have any cyber defenses in place. At the same time,
organizations of all sizes are facing a global cybersecurity skills shortage,
with almost 3.5 m illion open jobs worldwide, 500,000 of them in the US
alone.
Cyber Attack Examples
Here are a few recent examples of cyber attacks that had a global impact.
Kaseya Ransomware Attack
Kaseya, a US -based provider of remote management software,
experienced a s upply chain attack, which was made public on July 2,
2021. The company announced that attackers could use its VSA product to
infect customer machines with ransomware.
SolarWinds Supply Chain Attack
This was a massive, highly innovative supply chain attack detected in
December 2020, and named after its victim, Austin -based IT management
company SolarWinds. It was conducted by APT 29, an organized
cybercrime group connected to the Russian government.
Amazon DDoS Attack
In February 2020, Amazon Web Services (A WS) was the target of a large -
scale distributed denial of service (DDoS) attack. The company
experienced and mitigated a 2.3 Tbps (terabits per second) DDoS attack,
which had a packet forwarding rate of 293.1 Mpps and a request rate per
second (rps) of 694 ,201. It is considered one of the largest DDoS attacks
in history.
Microsoft Exchange Remote Code Execution Attack
In March 2021, a large -scale cyber attack was carried out against
Microsoft Exchange, a popular enterprise email server. It leveraged four
separate zero-day vulnerabilities discovered in Microsoft Exchange
servers.
Twitter Celebrities Attack
In July 2020, Twitter was breached by a group of three attackers, who
took over popular Twitter accounts. They used social engineering attacks
to steal emp loyee credentials and gain access to the company’s internal
management systems, later identified by Twitter as vishing (phone
phishing).
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11 Other Notable Attacks
2018
 Marriott’s Starwood Hotels announced a breach that leaked the
personal data of more than 50 0 million guests.
 UnderArmor’s MyFitnessPal brand leaked the email addresses and
login information of 150 million user accounts.
2017
 The WannaCry ransomware attack affected more than 300,000
computers in 150 countries, causing billions of dollars in damag es.
 Equifax experienced open source vulnerability in an unpatched
software component, which leaked the personal information of 145
million people.
2016
 The NotPetya attack hit targets around the world, with several waves
continuing for more than a year, co sting more than $10 billion in
damage.
 An attack on the FriendFinder adult dating website compromised the
data of 412 million users.
 Yahoo’s data breach incident compromised the accounts of 1 billion
users, not long after a previous attack exposed personal information
contained in 500 million user accounts.
Types of Cyber Attacks
While there are thousands of known variants of cyber attacks, here are a
few of the most common attacks experienced by organizations every day.
Ransomware
Ransomware is malware tha t uses encryption to deny access to resources
(such as the user’s files), usually in an attempt to compel the victim to pay
a ransom. Once a system has been infected, files are irreversibly
encrypted, and the victim must either pay the ransom to unlock the
encrypted resources, or use backups to restore them.
Ransomware is one of the most prevalent types of attacks, with some
attacks using extortion techniques, such as threatening to expose sensitive
data if the target fails to pay the ransom. In many cases, paying the ransom
is ineffective and does not restore the user’s data.
Malware
There are many types of malware, of which ransomware is just one
variant. Malware can be used for a range of objectives from stealing munotes.in

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12 information, to defacing or altering web c ontent, to damaging a computing
system permanently.
The malware landscape evolves very quickly, but the most prevalent
forms of malware are:
 Botnet Malware —adds infected systems to a botnet, allowing
attackers to use them for criminal activity
 Cryptominers —mines cryptocurrency using the target’s computer
 Infostealers —collects sensitive information on the target’s computer
 Banking trojans —steals financial and credential information for
banking websites
 Mobile Malware —targets devices via apps or SMS
 Rootkits —gives the attacker complete control over a device’s
operating system
DoS and DDoS Attacks
Denial -of-service (DoS) attacks overwhelm the target system so it cannot
respond to legitimate requests. Distributed denial -of-service (DDoS)
attacks are similar but involve multiple host machines. The target site is
flooded with illegitimate service requests and is forced to deny service to
legitimate users. This is because servers consume all available resources to
respond to the request overload.
These attacks don’t provide the attacker with access to the target system or
any direct benefit. They are used purely for the purpose of sabotage, or as
a diversion used to distract security teams while attackers carry out other
attacks.
Firewalls and network security soluti ons can help protect against small -
scale DoS attacks. To protect against large scale DDoS, organizations
leverage cloud -based DDoS protection which can scale on demand to
respond to a huge number of malicious requests.
Phishing and Social Engineering Attac ks
Social engineering is an attack vector that relies heavily on human
interaction, used in over 90% of cyberattacks. It involves impersonating a
trusted person or entity, and tricking individuals into granting an attacker
sensitive information, transferri ng funds, or providing access to systems or
networks.
Phishing attacks occur when a malicious attacker obtains sensitive
information from a target and sends a message that appears to be from a
trusted and legitimate source. The name “phishing” alludes to t he fact that
attackers are “fishing” for access or sensitive information, baiting the
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13 As part of a phishing message, attackers typically send links to malicious
websites, prompt the user to d ownload malicious software, or request
sensitive information directly through email, text messaging systems or
social media platforms. A variation on phishing is “spear phishing”, where
attackers send carefully crafted messages to individuals with special
privileges, such as network administrators, executives, or employees in
financial roles.
MitM Attacks
Man-in-the-Middle (MitM) attacks are breaches that allow attackers to
intercept the data transmitted between networks, computers or users. The
attacker is positioned in the “middle” of the two parties and can spy on
their communication, often without being detected. The attacker can also
modify messages before sending them on to the intended recipient.
You can use VPNs or apply strong encryption to access p oints to protect
yourself from MitM attacks.
Fileless Attacks
Fileless attacks are a new type of malware attack, which takes advantage
of applications already installed on a user’s device. Unlike traditional
malware, which needs to deploy itself on a targe t machine, fileless attacks
use already installed applications that are considered safe, and so are
undetectable by legacy antivirus tools.
Fileless malware attacks can be triggered by user -initiated actions, or may
be triggered with no user action, by exp loiting operating system
vulnerabilities. Fileless malware resides in the device’s RAM and
typically access native operating system tools, like PowerShell and
Windows Management Instrumentation (WMI) to inject malicious code.
A trusted application on a pri vileged system can carry out system
operations on multiple endpoints, making them ideal targets for fileless
malware attacks.
1.4.1 Malicious program
Malicious programs can be divided into the following groups: worms,
viruses, trojans, hacker utilities and other malware. All of these are
designed to damage the infected machine or other networked machines.
This category includes programs that propagate via LANs or the Internet
with the following objectives: Penetrating remote machines.
1.4.2 Non-malicious pr ogram
Nonmalicious Program Errors Being human, programmers and other
developers make many mistakes, most of which are unintentional
and nonmalicious . Many such errors cause program malfunctions but do
not lead to more serious security vulnerabilities.
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14 1.5 TYPES OF COMPUTER CRIMINALS[4]
1) Script kiddies : A wannabe hacker. Someone who wants to be a hacker
(or thinks they are) but lacks any serious technical expertise. They are
usually only able to attack very weakly secured systems.
2) Scammers: Your email inbox is probably full of their work. Discount
pharmaceuticals, time -shares, personal ads from available women in
Russia…sound familiar?
3) Hacker groups: Usually work anonymously and create tools for
hacking. They often hack computers for no criminal reason and are
sometimes even hired by companies wanting to test their security.
4) Phishers: Gotten an email recently claiming your bank account is abou t
to expire? Don’t fall for these jerks. They want your personal
information and, most likely, your identity, by directing you to a phony
websites.
5) Political/rel igious/commercial groups: Tend to not be interested in
financial gain. These guys develop malware for political ends. If you think
this group is harmless, think Stuxnet . The Stuxnet worm which a ttacked
Iran’s Atomic Program of Its Nuclear Facilities was believed to be created
by a foreign government.
6) Insiders : They may only be 20% of the threat, but they produce 80% of
the damage. These attackers are considered to be the highest risk. To make
matters worse, as the name suggests, they often reside within an
organization.
1.6 SUMMARY
Information Security is not only about securing information from
unauthorized access. Information Security is basically the practice of
preventing unauthorized acces s, use, disclosure, disruption, modification,
inspection, recording or destruction of information. Information can be
physical or electronic one.
1.7 REFERENCE FOR FURTHER READING
1. https://www.techtarget.com/searchsecurity/definition/securityecurity?
(techtarget.com)
2. https://www.techtarget.com/search security/definition/securityles of
Security (educba.com)
3. https://www.faronics.com/news/blog/7 -types -of-cyber -criminalscom)
4. https://www.faronics.com/news/blog/7 -types -of-cyber -criminals
5. https://cyberthreatportal.com/types -of-computer -security/
rthreatportal.com)
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OPERATING SYSTEM SECURITY
Unit Structure :
2.0 Objectives
2.1 Introduction
2.2 Protect Objects and methods of protection
2.3 Memoryaddress protection
2.3.1 Fence
2.3.2 Relocation
2.3.3 Base/ bound Registers
2.3.4 Tagged Architecture
2.3.5 Segmentation
2.3.6 Paging
2.3.7 Directory
2.3.8 Access Control List
2.4 Summary
2.5 References for further reading
2.0 OBJECTIVES
1. To understand the concepts of memory address protection
2. To understand access control list
3. To understand the importance of Memory Man agement
4. To understand the how segmentation can help in proper Memory
Management.
2.1 INTRODUCTION
Operating system security (OS security) is the process of ensuring OS
integrity, confidentiality and availability.OS security refers to specified
steps o r measures used to protect the OS from threats, viruses, worms,
malware or remote hacker intrusions. OS security encompasses all
preventive -control techniques, which safeguard any computer assets
capable of being stolen, edited or deleted if OS security is compromised.
2.2 PROTECTED OBJECTS AND METHODS OF
PROTECTION
To make your operating system secure, we need to protect operating
system objects like memory, sharable I/O devices, such as disk , serially
reusable I/O devices, such as printers and tape driv es, sharable programs
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2.3 MEMORY ADDRESS PROTECTION
The most obvious problem of multiprogramming is preventing one
program from affecting the data and programs in the memory space of
other users. Fortunatel y, protection can be built into the hardware
mechanisms that control efficient use of memory, so solid protection can
be provided at essentially no additional cost.
2.3.1 Fence
The simplest form of memory protection was introduced in single -user
operating systems to prevent a faulty user program from destroying part of
the resident portion of the operating system. As its name implies, a fence
is a method to confine users to one side of a boundary.

In one implementation, the fence was a predefined memory ad dress,
enabling the operating system to reside on one side and the user to stay on
the other. Unfortunately, this kind of implementation was very restrictive
because a predefined amount of space was always reserved for the
operating system, whether it was needed or not. If less than the predefined
space was required, the excess space was wasted. Conversely, if the
operating system needed more space, it could not grow beyond the fence
boundary.

Fig 2.3.1.1: Fixed Fence[1]

Another implementation used a ha rdware register, often called a fence
register , containing the address of the end of the operating system. In
contrast to a fixed fence, in this scheme the location of the fence could be
changed. Each time a user program generated an address for data
modif ication, the address was automatically compared with the fence
address. If the address was greater than the fence address (that is, in the munotes.in

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17 user area), the instruction was executed; if it was less than the fence
address (that is, in the operating system are a), an error condition was
raised.



2.3.1.2: Variable Fence Register[1]

A fence register protects only in one direction. In other words, an
operating system can be protected from a single user, but the fence cannot
protect one user from another user. Similarly, a user cannot identify
certain areas of the program as inviolable (such as the code of the program
itself or a read -only data area).

2.3.2 Relocation
If the operating system can be assumed to be of a fixed size, programmers
can write their code assuming that the program begins at a constant
address. This feature of the operating system makes it easy to determine
the address of any object in the program. However, it also makes it
essentially impossible to change the starting address if, for examp le, a new
version of the operating system is larger or smaller than the old. If the size
of the operating system is allowed to change, then programs must be
written in a way that does not depend on placement at a specific location
in memory.

Relocation is the process of taking a program written as if it began at
address 0 and changing all addresses to reflect the actual address at which
the program is located in memory. In many instances, this effort merely
entails adding a constant relocation factor to ea ch address of the program.
That is, the relocation factor is the starting address of the memory
assigned for the program.Conveniently, the fence register can be used in
this situation to provide an important extra benefit: The fence register can
be a hardw are relocation device. The contents of the fence register are
added to each program address. This action both relocates the address and munotes.in

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18 guarantees that no one can access a location lower than the fence address.
(Addresses are treated as unsigned integers, so adding the value in the
fence register to any number is guaranteed to produce a result at or above
the fence address.) Special instructions can be added for the few times
when a program legitimately intends to access a location of the operating
system.

2.3.3 Base/Bounds Registers
A major advantage of an operating system with fence registers is the
ability to relocate; this characteristic is especially important in a multiuser
environment. With two or more users, none can know in advance where a
program will be loaded for execution. The relocation register solves the
problem by providing a base or starting address. All addresses inside a
program are offsets from that base address. A variable fence register is
generally known as a base register.

Fence reg isters provide a lower bound (a starting address) but not an upper
one. An upper bound can be useful in knowing how much space is allotted
and in checking for overflows into "forbidden" areas. The second register,
called a bounds register, is an upper addr ess limit, in the same way that a
base or fence register is a lower address limit. Each program address is
forced to be above the base address because the contents of the base
register are added to the address; each address is also checked to ensure
that i t is below the bounds address. In this way, a program's addresses are
neatly confined to the space between the base and the bounds registers.

Fig 2.3.3.1 : Pair of Base/Bounds Registers

This technique protects a program's addresses from modification by
another user. When execution changes from one user's program to
another's, the operating system must change the contents of the base and
bounds registers to reflect the true address space for that user. This change
is part of the general preparation, call ed a context switch, that the
operating system must perform when transferring control from one user to
another.

With a pair of base/bounds registers, a user is perfectly protected from
outside users, or, more correctly, outside users are protected from er rors in
any other user's program. Erroneous addresses inside a user's address
space can still affect that program because the base/bounds checking munotes.in

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19 guarantees only that each address is inside the user's address space. For
example, a user error might occur w hen a subscript is out of range or an
undefined variable generates an address reference within the user's space
but, unfortunately, inside the executable instructions of the user's program.
In this manner, a user can accidentally store data on top of instr uctions.
Such an error can let a user inadvertently destroy a program, but
(fortunately) only the user's own program.

We can solve this overwriting problem by using another pair of
base/bounds registers, one for the instructions (code) of the program and a
second for the data space. Then, only instruction fetches (instructions to be
executed) are relocated and checked with the first register pair, and only
data accesses (operands of instructions) are relocated and checked with the
second register pair.

Although two pairs of registers do not prevent all program errors, they
limit the effect of data -manipulating instructions to the data space. The
pairs of registers offer another more important advantage: the ability to
split a program into two pieces that can be relocated separately.


Fig 2.3.3.2: Two pairs of Base/Bounds Registers

These two features seem to call for the use of three or more pairs of
registers: one for code, one for read -only data, and one for modifiable data
values. Although in theory t his concept can be extended, two pairs of
registers are the limit for practical computer design. For each additional
pair of registers (beyond two), something in the machine code of each
instruction must indicate which relocation pair is to be used to addr ess the
instruction's operands. That is, with more than two pairs, each instruction
specifies one of two or more data spaces. But with only two pairs, the
decision can be automatic: instructions with one pair, data with the other.

2.3.4 Tagged Architectur e
Another problem with using base/bounds registers for protection or
relocation is their contiguous nature. Each pair of registers confines
accesses to a consecutive range of addresses. A compiler or loader can
easily rearrange a program so that all code s ections are adjacent and all
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20
However, in some cases you may want to protect some data values but not
all. For example, a personnel record may require protecting the field for
salary but not office location and phone number. Mor eover, a programmer
may want to ensure the integrity of certain data values by allowing them to
be written when the program is initialized but prohibiting the program
from modifying them later. This scheme protects against errors in the
programmer's own co de. A programmer may also want to invoke a shared
subprogram from a common library. We can address some of these issues
by using good design, both in the operating system and in the other
programs being run. These characteristics dictate that one program m odule
must share with another module only the minimum amount of data
necessary for both of them to do their work.

Additional, operating -system -specific design features can help, too.
Base/bounds registers create an all -or-nothing situation for sharing: Ei ther
a program makes all its data available to be accessed and modified or it
prohibits access to all. Even if there were a third set of registers for shared
data, all data would need to be located together. A procedure could not
effectively share data ite ms A, B, and C with one module, A, C, and D
with a second, and A, B, and D with a third. The only way to accomplish
the kind of sharing we want would be to move each appropriate set of data
values to some contiguous space. However, this solution would not be
acceptable if the data items were large records, arrays, or structures.

An alternative is tagged architecture , in which every word of machine
memory has one or more extra bits to identify the access rights to that
word. These access bits can be set onl y by privileged (operating system)
instructions. The bits are tested every time an instruction accesses that
location.

One memory location may be protected as execute -only (for example, the
object code of instructions), whereas another is protected for fe tch-only
(for example, read) data access, and another accessible for modification
(for example, write). In this way, two adjacent locations can have different
access rights. Furthermore, with a few extra tag bits, different classes of
data (numeric, charac ter, address or pointer, and undefined) can be
separated, and data fields can be protected for privileged (operating
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21

Fig 2.3.4: Tagged Architecture
This protection technique has been used on a few systems, although the
number of tag bits has been rather small. The Burroughs B6500 -7500
system used three tag bits to separate data words (three types), descriptors
(pointers), and control words (stack pointers and addressing control
words). The IBM System/38 used a tag to control both inte grity and
access.

A variation used one tag that applied to a group of consecutive locations,
such as 128 or 256 bytes. With one tag for a block of addresses, the added
cost for implementing tags was not as high as with one tag per location.
The Intel I960 extended architecture processor used a tagged architecture
with a bit on each memory word that marked the word as a "capability,"
not as an ordinary location for data or instructions. A capability controlled
access to a variable -sized memory block or segm ent. This large number of
possible tag values Supported memory segments that ranged in size from
64 to 4 billion bytes, with a potential 2256 different protection domains.

Compatibility of code presented a problem with the acceptance of a tagged
architect ure. A tagged architecture may not be as useful as more modern
approaches, as we see shortly. Some of the major computer vendors are
still working with operating systems that were designed and implemented
many years ago for architectures of that era. Indee d, most manufacturers
are locked into a more conventional memory architecture because of the
wide availability of components and a desire to maintain compatibility
among operating systems and machine families. A tagged architecture
would require fundamenta l changes to substantially all the operating
system code, a requirement that can be prohibitively expensive. But as the
price of memory continues to fall, the implementation of a tagged
architecture becomes more feasible.

2.3.5 Segmentation
We present two more approaches to protection, each of which can be
implemented on top of a conventional machine structure, suggesting a
better chance of acceptance. Although these approaches are ancient by
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22 have been implemented on many machines since then. Furthermore, they
offer important advantages in addressing, with memory protection being a
delightful bonus.

The first of these two approaches, segmentation , involves the simple
notion of dividing a pro gram into separate pieces. Each piece has a logical
unity, exhibiting a relationship among all of its code or data values. For
example, a segment may be the code of a single procedure, the data of an
array, or the collection of all local data values used b y a particular module.
Segmentation was developed as a feasible means to produce the effect of
the equivalent of an unbounded number of base/bounds registers. In other
words, segmentation allows a program to be divided into many pieces
having different acc ess rights.Each segment has a unique name. A code or
data item within a segment is addressed as the pair , where
name is the name of the segment containing the data item and offset is its
location within the segment (that is, its distance fro m the start of the
segment).

Logically, the programmer pictures a program as a long collection of
segments. Segments can be separately relocated, allowing any segment to
be placed in any available memory locations. The relationship between a
logical segme nt and its true memory position is shownin fig.


Fig 2.3.5.1: Logical and Physical Representation of Segments

The operating system must maintain a table of segment names and their
true addresses in memory. When a program generates an address of the
form , the operating system looks up name in the segment
directory and determines its real beginning memory address. To that
address the operating system adds offset, giving the true memory address
of the code or data item. For efficiency there is usually one operating
system segment address table for each process in execution. Two
processes that need to share access to a single segment would have the
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23

Fig 2.3.5.2: Translation of Segment Addre ss

Thus, a user's program does not know what true memory addresses it uses.
It has no wayand no needto determine the actual address associated with a
particular . The pair is adequate to access
any data or instruction to which a program should have access.

This hiding of addresses has three advantages for the operating system.
 The operating system can place any segment at any location or move
any segment to any location, even after the program begins to execute.
Because it tra nslates all address references by a segment address table,
the operating system needs only update the address in that one table
when a segment is moved.
 A segment can be removed from main memory (and stored on an
auxiliary device) if it is not being used c urrently.
 Every address reference passes through the operating system, so there
is an opportunity to check each one for protection.
 Because of this last characteristic, a process can access a segment only
if that segment appears in that process's segment t ranslation table. The
operating system controls which programs have entries for a particular
segment in their segment address tables. This control provides strong
protection of segments from access by unpermitted processes. For
example, program A might hav e access to segments BLUE and
GREEN of user X but not to other segments of that user or of any
other user. In a straightforward way we can allow a user to have
different protection classes for different segments of a program. For
example, one segment might be read -only data, a second might be
execute -only code, and a third might be writeable data. In a situation
like this one, segmentation can approximate the goal of separate
protection of different pieces of a program, as outlined in the previous
section o n tagged architecture.
 Segmentation offers these security benefits:
 Each address reference is checked for protection.
 Many different classes of data items can be assigned different levels of
protection.
 Two or more users can share access to a segment, with potentially
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24  A user cannot generate an address or access to an unpermitted
segment.

One protection difficulty inherent in segmentation concerns segment size.
Each segment has a particular size. However, a program can generate a
reference to a valid segment name, but with an offset beyond the end of
the segment. For example, reference looks perfectly valid, but
in reality segment A may be only 200 bytes long. If left unplugged, this
security hole could allow a program to ac cess any memory address beyond
the end of a segment just by using large values of offset in an address.

This problem cannot be stopped during compilation or even when a
program is loaded, because effective use of segments requires that they be
allowed to grow in size during execution. For example, a segment might
contain a dynamic data structure such as a stack. Therefore, secure
implementation of segmentation requires checking a generated address to
verify that it is not beyond the current end of the segm ent referenced.
Although this checking results in extra expense (in terms of time and
resources), segmentation systems must perform this check; the
segmentation process must maintain the current segment length in the
translation table and compare every add ress generated.

Thus, we need to balance protection with efficiency, finding ways to keep
segmentation as efficient as possible. However, efficient implementation
of segmentation presents two problems: Segment names are inconvenient
to encode in instructi ons, and the operating system's lookup of the name in
a table can be slow. To overcome these difficulties, segment names are
often converted to numbers by the compiler when a program is translated;
the compiler also appends a linkage table matching numbers to true
segment names. Unfortunately, this scheme presents an implementation
difficulty when two procedures need to share the same segment because
the assigned segment numbers of data accessed by that segment must be
the same.

2.3.6 Paging
One alternativ e to segmentation is paging . The program is divided into
equal -sized pieces called pages, and memory is divided into equal -sized
units called page frames . (For implementation reasons, the page size is
usually chosen to be a power of two between 512 and 409 6 bytes.) As
with segmentation, each address in a paging scheme is a two -part object,
this time consisting of .

Each address is again translated by a process similar to that of
segmentation: The operating system maintains a table of user pag e
numbers and their true addresses in memory. The page portion of every
reference is converted to a page frame address by a table
lookup; the offset portion is added to the page frame address to produce
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25

Fig 2.3.6.1: Page Address Translation

Unlike segmentation, all pages in the paging approach are of the same
fixed size, so fragmentation is not a problem. Each page can fit in any
available page in memory, and thus there i s no problem of addressing
beyond the end of a page. The binary form of a address is
designed so that the offset values fill a range of bits in the address.
Therefore, an offset beyond the end of a particular page results in a carry
into the page portion of the address, which changes the address.

To see how this idea works, consider a page size of 1024 bytes (1024 =
210), where 10 bits are allocated for the offset portion of each address. A
program cannot generate an offset value larger than 1023 in 10 bits.
Moving to the next location after causes a carry into the page
portion, thereby moving translation to the next page. During the
translation, the paging process checks to verify that a offset>reference does not exceed the m aximum number of pages the
process has defined.
With a segmentation approach, a programmer must be conscious of
segments. However, a programmer is oblivious to page boundaries when
using a paging -based operating system. Moreover, with paging there is no
logical unity to a page; a page is simply the next 2n bytes of the program.
Thus, a change to a program, such as the addition of one instruction,
pushes all subsequent instructions to lower addresses and moves a few
bytes from the end of each page to the st art of the next. This shift is not
something about which the programmer need be concerned because the
entire mechanism of paging and address translation is hidden from the
programmer.
However, when we consider protection, this shift is a serious problem.
Because segments are logical units, we can associate different segments
with individual protection rights, such as read -only or execute -only. The
shifting can be handled efficiently during address translation. But with
paging there is no necessary unity to the items on a page, so there is no munotes.in

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26 way to establish that all values on a page should be protected at the same
level, such as read -only or execute -only.
Combined Paging with Segmentation
We have seen how paging offers implementation efficiency, while
segme ntation offers logical protection characteristics. Since each approach
has drawbacks as well as desirable features, the two approaches have been
combined.
The IBM 390 family of mainframe systems used a form of paged
segmentation. Similarly, the Multics ope rating system (implemented on a
GE-645 machine) applied paging on top of segmentation. In both cases,
the programmer could divide a program into logical segments. Each
segment was then broken into fixed -size pages. In Multics, the segment
name portion of a n address was an 18 -bit number with a 16 -bit offset. The
addresses were then broken into 1024 -byte pages. This approach retained
the logical unity of a segment and permitted differentiated protection for
the segments, but it added an additional layer of tr anslation for each
address. Additional hardware improved the efficiency of the
implementation.

Fig 2.3.6.2: Page Segmentation
2.3.7 Directory
One simple way to protect an object is to use a mechanism that works like
a file directory. Imagine we are tryin g to protect files (the set of objects)
from users of a computing system (the set of subjects). Every file has a
unique owner who possesses "control" access rights (including the rights
to declare who has what access) and to revoke access to any person at any
time. Each user has a file directory, which lists all the files to which that
user has access.
Clearly, no user can be allowed to write in the file directory because that
would be a way to forge access to a file. Therefore, the operating system
must ma intain all file directories, under commands from the owners of munotes.in

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27 files. The obvious rights to files are the common read, write, and execute
familiar on many shared systems. Furthermore, another right, owner, is
possessed by the owner, permitting that user to grant and revoke access
rights. Figure shows an example of a file directory.

Fig 2.3.7: Directory Access
This approach is easy to implement because it uses one list per user,
naming all the objects that user is allowed to access. However, several
diffic ulties can arise. First, the list becomes too large if many shared
objects, such as libraries of subprograms or a common table of users, are
accessible to all users. The directory of each user must have one entry for
each such shared object, even if the us er has no intention of accessing the
object. Deletion must be reflected in all directories.
A second difficulty is revocation of access . If owner A has passed to user
B the right to read file F, an entry for F is made in the directory for B. This
grantin g of access implies a level of trust between A and B. If A later
questions that trust, A may want to revoke the access right of B. The
operating system can respond easily to the single request to delete the right
of B to access F because that action involv es deleting one entry from a
specific directory. But if A wants to remove the rights of everyone to
access F, the operating system must search each individual directory for
the entry F, an activity that can be time consuming on a large system. For
example, large timesharing systems or networks of smaller systems can
easily have 5,000 to 10,000 active accounts. Moreover, B may have
passed the access right for F to another user, so A may not know that F's
access exists and should be revoked. This problem is p articularly serious
in a network.
2.3.8 Access Control List
access -control list ( ACL) is a list of permissions associated with a
system resource (object) . An ACL specifies which users or system
processes are granted access to objects, as well as what oper ations are
allowed on given objects. Each entry in a typical ACL specifies a subject
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28 We can think of the directory as a listing of objects accessible by a single
subject, and the access list as a table identifying subjects that can access a
single object. The data in these two representations are equivalent, the
distinction being the ease of use in given situations.
As an alternative, we can use an access control matrix , a table in which
each row represents a subject, each column represent s an object, and each
entry is the set of access rights for that subject to that object. An example
representation of an access control matrix is shown following table. In
general, the access control matrix is sparse (meaning that most cells are
empty): Mo st subjects do not have access rights to most objects. The
access matrix can be represented as a list of triples, having the form
. Searching a large number of these triples is
inefficient enough that this implementation is seldom used.
Table 2.3.8: Access Control Matrix

2.4 SUMMARY
Basically the operating system objects are plays important role for
operating system and it is just like protecting one user's programs and data
from other users' programs became an important iss ue in multi -
programmed operating systems and memory. An ACL specifies which
users or system processes are granted access to objects, as well as what
operations are allowed on given objects. Each entry in a typical ACL
specifies a subject and an operation.
2.5 REFERENCE FOR FURTHER READING
1. https://www.brainkart.com/article/File -Protection -Mechanisms_9610/

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29 3
NETWORK SECURITY -I
Unit Structure :
3.0 Objectives
3.1 Introduction
3.2 Network Security
3.2.1 Different types of network layer attacks
3.2.2 Firewall
3.2.3 ACL
3.2.4 Packet Filtering
3.2.5 DMZ
3.2.6 Alerts and Audit Trials
3.2.7 IDS
3.2.8 Signat ure based
3.2.9 Anomaly based
3.2.10 IPS
3.2.11 Policy based
3.2.12 Honeypot based
3.3 Web Server Security
3.3.1 SSLBasic Protocol
3.3.2 TLS
3.3.3 Client Authentication
3.3.4 PKI
3.3.5 Encoding
3.3.6 Secure Electronic Transaction (SET)
3.3.7 Kerberos
3.4 Let us Sum Up
3.5 List of References
3.6 Summary
3.7 Bibliography
3.8 Unit End Exercises munotes.in

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30 3.0 OBJECTIVES
After going through this unit, you will be able to:
1. To understand the need for network security
2. To identify and classify particular exampl es of attacks
3. To define the terms vulnerability, threat and attack
4. To identify physical points of vulnerability in simple networks
5. To identify firewall, Intrusion detection and prevention system.
3.1 INTRODUCTION
Network security mainly refers to an evalua tion which is taken by any
enterprise or an organization to secure or to make safe its computer
network. Its main role is to maintain confidentiality and accessibility of
the data and network. In every enterprise or an organization which
generally manages or handles a large amount of data needs some infusion
aginst many cyber threats. The most common example of network security
is to handle the password protection. Network security has become the
main subject of cyber security. Network security deals with v arious levels
which helps in performing the activities needed for handles the large
amount of data in a secure manner.
3.2 NETWORK SECURITY
Network security is a broad term that covers a multitude of technologies,
devices and processes. In its simplest ter m, it is a set of rules and
configurations designed to protect the integrity, confidentiality and
accessibility of computer networks and data using both software and
hardware technologies. Every organization, regardless of size, industry or
infrastructure, requires a degree of network security solutions in place to
protect it from the ever -growing landscape of cyber threats in the wild
today.
Today's network architecture is complex and is faced with a threat
environment that is always changing and attackers that are always trying
to find and exploit vulnerabilities. These vulnerabilities can exist in a
broad number of areas, including devices, data, applications, users and
locations. For this reason, there are many network security management
tools and appli cations in use today that address individual threats and
exploits and also regulatory non -compliance. When just a few minutes of
downtime can cause widespread disruption and massive damage to an
organization's bottom line and reputation, it is essential th at these
protection measures are in place.

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31 3.2.1 Different types of network layer attacks
The main responsibility of the network layer is to transmit the packets
from the source to the destination by finding the best route, which is the
route that has the lowest cost and shortest path from the source to the
destination. The goal of the attacks on the Network Layer is to disrupt the
path between the source and destination that is chosen from the routing
protocols. [3]. Some of the most used methods to attack the network layer
are below:
a. IP spoofing attack:
This technique is used from the attackers to gain unauthorized access to
the servers. The attacker will send messages to the server not with his own
IP address, but with a “trusted” IP address. In this way the server will not
understand that it is getting traffic from an attacker. After the attacker will
find the “trusted IP” address, will modify the headers of the packets in the
way that the attacked server will think the packets are coming from
“trusted” I P. The main route cause of DDoS (Distributed Denial of
Service) attacks is IP spoofing.

b. Hijacking attack
Another method used to attack the network layer is hijacking. These
attacks are easy to implement, but difficult to detect. The basic idea of the
attack is to disrupt a session between client and server and take over the IP
address of the trusted client. The next step of the attacker is to discontinue
the communication between the server and the trusted client and to create
a new session with server by pretending to be the trusted client. After the
new connection is created, the attacker can take the data he wants from
server until this attack will be detect from the victim client (trusted IP) or
from the server. These attacks happens when the server is unware for a
certain amount of time of the existence of an attacker on the network and
the legitimate client that is disconnected from the network (from the
attacker), the attacker will make sure to keep it unaware of the attack. The
attackers usually use different tools to monitor the victim’s network, such
as WirelessMon, Ethereal, Netstumbler. If the wireless network will not munotes.in

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32 use advanced encryption methods, and different authentication
mechanism, the possibilities to be attacked using hijacking will be high.

c. The Smurf attack
This attacking technique is a DoS (Denial of Service) attack that happen
on the network layer. These attacks are very easy to implement. The idea
of this attack is to overload a server with packets. The attacker will send a
high n umber of packets from a spoofed IP address to the server. The main
goal of these attacks is to disable the service the network is providing.
Many techniques of attacking are used to achieve this goal. When the
attacker wants to realize a Smurf attack, he w ill transmit to the intended
victim a large number of Internet Control Message Protocol (ICMP) by
using an IP broadcast address. To achieve this, the attackers use a program
called “smurf” that builds a network packet which appears at the attacked
server a s it is coming from the trusted IP address. When the attacked
server will receive this ICMP packets, by default the server will response
to the request. The “smurf” program will generate the necessary amount of
ICMP requests to overload the victim with ICM P requests and responses
until this device will not be able to provide the necessary services on the
network.
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33 d. Wormhole attacks
These attacks are the most severe attacks and complicated attacks in
wireless network. Wormhole attacks are very hard to detec t and to protect
from them. Even when all the communication on the wireless network
provides authenticity and confidentiality, a wormhole attack can happen.
The attackers will record the packets at one point of the network and
retransmits them to another p oint of the network using private highspeed
network, and then replays them into the network from that point. These
kinds of attacks are a serious threat against network routing protocols.
Usually in the wireless network, routing protocols have implemented
different mechanisms to defend against wormhole attacks; otherwise, the
routing protocols will not be able to route more than one hop.

3.2.2 Firewall
Firewalls were officially invented in the early 1990s.
A firewall is a device that filters all traffic b etween a protected or "inside"
network and a less trustworthy or "outside" network. Usually, a firewall
runs on a dedicated device; because it is a single point through which
traffic is channeled, performance is important, which means nonfirewall
functions should not be done on the same machine. Because a firewall is
executable code, an attacker could compromise that code and execute
from the firewall's device. Thus, the fewer pieces of code on the device,
the fewer tools the attacker would have by compromi sing the firewall.
Firewall code usually runs on a proprietary or carefully minimized
operating system.
The purpose of a firewall is to keep "bad" things outside a protected
environment. To accomplish that, firewalls implement a security policy
that is spe cifically designed to address what bad things might happen. For
example, the policy might be to prevent any access from outside (while
still allowing traffic to pass from the inside to the outside). Alternatively,
the policy might permit accesses only from certain places, from certain
users, or for certain activities. Part of the challenge of protecting a network
with a firewall is determining which security policy meets the needs of the
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34 firewall is a type of host; it often is as programmable as a good -quality
workstation.


Personal Firewalls:
Firewalls typically protect a (sub)network of multiple hosts. University
students and employees in offices are behind a real firewall. Increasingly,
home users, individual workers, and small businesses use cable modems
or DSL connections with unlimited, always -on access. These people need
a firewall, but a separate firewall computer to protect a single workstation
can seem too complex and expensive. These people need a firewall's
capabilities at a lower price. A personal firewall is an application program
that runs on a workstation to block unwanted traffic, usually from the
network. A personal firewall can complement the work of a conventional
firewall by screening the kind of data a single host will acc ept, or it can
compensate for the lack of a regular firewall, as in a private DSL or cable
modem connection. Just as a network firewall screens incoming and
outgoing traffic for that network, a personal firewall screens traffic on a
single workstation. A w orkstation could be vulnerable to malicious code
or malicious active agents’ leakage of personal data stored on the
workstation, and vulnerability scans to identify potential weaknesses.
3.2.3 ACL (Access Control List)
An access control list (ACL) contains rules that grant or deny access to
certain digital environments. There are two types of ACLs:
 Filesystem ACLs ━filter access to files and/or directories. Filesystem
ACLs tell operating systems which users can access the system, and
what privileges the user s are allowed.
 Networking ACLs ━filter access to the network. Networking ACLs tell
routers and switches which type of traffic can access the network, and
which activity is allowed.
 Originally, ACLs were the only way to achieve firewall protection.
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35 However, organizations continue to use ACLs in conjunction with
technologies like virtual private networks (VPNs) that specify which
traffic should be encrypted and transferred through a VPN tunnel.
Reasons to use an ACL:
 Traffic flow control
 Restricted network traffic for better network performance
 A level of security for network access specifying which areas of the
server/network/service can be accessed by a user and which cannot
 Granular monitorin g of the traffic exiting and entering the system
How ACL Works
A filesystem ACL is a table that informs a computer operating system of
the access privileges a user has to a sy stem object, including a single file
or a file directory. Each object has a security property that connects it to
its access control list. The list has an entry for every user with access
rights to the system.
Typical privileges include the right to read a single file (or all the files) in
a directory, to execute the file, or to write to the file or files. Operating
systems that use an ACL include, for example, Microsoft Windows
NT/2000, Novell’s Netware, Digital’s OpenVMS, and UNIX -based
systems.
When a us er requests an object in an ACL -based security model, the
operating system studies the ACL for a relevant entry and sees whether the
requested operation is permissible.
Networking ACLs are installed in routers or switches, where they act as
traffic filters . Each networking ACL contains predefined rules that control
which packets or routing updates are allowed or denied access to a
network.
Routers and switches with ACLs work like packet filters that transfer or
deny packets based on filtering criteria. As a Layer 3 device, a packet -
filtering router uses rules to see if traffic should be permitted or denied
access. It decides this based on source and destination IP addresses,
destination port and source port, and the official procedure of the packet.
Types of Access Control Lists
Access control lists can be approached in relation to two main categories:
Standard ACL
An access -list that is developed solely using the source IP address. These
access control lists allow or block the entire protocol suite. They don ’t
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36 numbers 1 -99 or 1300 -1999 so the router can recognize the address as the
source IP address.
Extended ACL
An access -list that is widely used as it can differentiate IP traffic. It use s
both source and destination IP addresses and port numbers to make sense
of IP traffic. You can also specify which IP traffic should be allowed or
denied. They use the numbers 100 -199 and 2000 -2699.
Access Control Lists (ACLs) are a collection of permits and deny
conditions, called rules, that provide security by blocking unauthorized
users and allowing authorized users to access specific resources.
ACLs can also provide traffic flow control, restrict contents of routing
updates, and decide which types of traffic are forwarded or blocked.
Normally ACLs reside in a firewall router or in a router connecting two
internal networks.
You can set up ACLs to control traffic at Layer 2, Layer 3, or Layer 4.
MAC ACLs operate on Layer 2. IP ACLs operate on Layers 3 an d 4.
ACL support features include Flow -based Mirroring and ACL Logging.
 Flow -based mirroring is the ability to mirror traffic that matches a
permit rule to a specific physical port or LAG. Flow -based mirroring is
similar to the redirect function, except th at in flow -based mirroring a
copy of the permitted traffic is delivered to the mirror interface while
the packet itself is forwarded normally through the device. You cannot
configure a given ACL rule with mirror and redirect attributes.
 ACL Logging provide s a means for counting the number of “hits”
against an ACL rule. When you configure ACL Logging, you augment
the ACL deny rule specification with a ‘log’ parameter that enables
hardware hit count collection and reporting. FASTPATH uses a fixed
five minute logging interval, at which time trap log entries are written
for each ACL logging rule that accumulated a non -zero hit count
during that interval. You cannot configure the logging interval.
Using ACLs to mirror traffic is called flow -based mirroring becaus e the
traffic flow is defined by the ACL classification rules. This is in contrast
to port mirroring, where all traffic encountered on a specific interface is
replicated on another interface.
To configure ACL we need to follow steps:
1. Create a MAC ACL by sp ecifying a name.
2. Create an IP ACL by specifying a number.
3. Add new rules to the ACL.
4. Configure the match criteria for the rules.
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37 3.2.4 Packet Filtering
A packet filtering gateway or screening router is the simplest, and in some
situations, the most effective type of firewall. A packet filtering gateway
controls access to packets on the basis of packet address (source or
destination) or specific transport protocol type (such as HTTP web traffic).
As described earlier in this chapter, putting ACLs on routers may severely
impede their performance. But a separate firewall behind (on the local
side) of the router can screen traffic before it gets to the protected network.
Figure shows a packet filter that blocks access fro m (or to) addresses in
one network; the filter allows HTTP traffic but blocks traffic using the
Telnet protocol.

3.2.5 DMZ
A demilitarized zone (DMZ) is a perimeter network that protects an
organization’s internal local -area network (LAN) from untrusted traffic.
A common demilitarized zone meaning is a subnetwork that sits between
the public internet and private networks. It exposes external -facing
services to untrusted networks and adds an extra layer of security
conditions to protect the sensitive data stored on internal networks, using
firewalls to filter traffic.
The end goal of a DMZ is to allow an organization to access untrusted
networks, such as the internet, while ensuring its private network or LAN
remains secure. Organizations typically store e xternal -facing services and
resources, as well as servers for the Domain Name System (DNS), File
Transfer Protocol (FTP), mail, proxy, Voice over Internet Protocol (VoIP),
and web servers, in the DMZ.
These servers and resources are isolated and given lim ited access to the
LAN to ensure they can be accessed via the internet but the internal LAN
cannot. As a result, a DMZ approach makes it more difficult for a hacker
to gain direct access to an organization’s data and internal servers via the
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38 A DM Z network provides a buffer between the internet and an
organization’s private network. The DMZ is isolated by a security
gateway, such as a firewall, that filters traffic between the DMZ and a
LAN. The default DMZ server is protected by another security g ateway
that filters traffic coming in from external networks.
It is ideally located between two firewalls, and the DMZ firewall setup
ensures incoming network packets are observed by a firewall —or other
security tools —before they make it through to the ser vers hosted in the
DMZ. This means that even if a sophisticated attacker is able to get past
the first firewall, they must also access the hardened services in the DMZ
before they can do damage to a business.
If an attacker is able to penetrate the externa l firewall and compromise a
system in the DMZ, they then also have to get past an internal firewall
before gaining access to sensitive corporate data. A highly skilled bad
actor may well be able to breach a secure DMZ, but the resources within it
should so und alarms that provide plenty of warning that a breach is in
progress.
Organizations that need to comply with regulations, such as the Health
Insurance Portability and Accountability Act (HIPAA), will sometimes
install a proxy server in the DMZ. This enab les them to simplify the
monitoring and recording of user activity, centralize web content filtering,
and ensure employees use the system to gain access to the internet.

3.2.6 Alerts and Audit Trials
Audit trails maintain a record of system activity both by system
andapplication processes and by user activity of systems and applications.
Inconjunction with appropriate tools and procedures, audit trails can
assistin detecting security violations, performance problems, and flaws in
applications. This bull etin focuses on audit trails as a technical controland
discusses the benefits and objectives of audit trails, the types ofaudit trails,
and some common implementation issues.
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39 An audit trail is a series of records of computer events, about anoperating
system, an application, or user activities. A computer systemmay have
several audit trails, each devoted to a particular type ofactivity. Auditing
is a review and analysis of management, operational,and technical
controls. The auditor can obtain valuable in formation aboutactivity on a
computer system from the audit trail. Audit trails improvethe auditability
of the computer system.
Audit trails may be used as either a support for regular system
operationsor a kind of insurance policy or as both of these. As insurance,
audittrails are maintained but are not used unless needed, such as after
asystem outage. As a support for operations, audit trails are used to
helpsystem administrators ensure that the system or resources have not
beenharmed by hackers, insi ders, or technical problems.
BENEFITS AND OBJECTIVES
Audit trails can provide a means to help accomplish severalsecurity -
related objectives, including individual accountability,reconstruction of
events (actions that happen on a computer system), intrusion detection,
and problem analysis.
Individual Accountability
Audit trails are a technical mechanism that help managers
maintainindividual accountability. By advising users that they are
personallyaccountable for their actions, which are tracked by an audit trail
thatlogs user activities, managers can help promote proper user
behavior.Users are less likely to attempt to circumvent security policy if
they knowthat their actions will be recorded in an audit log.
For example, audit trails can be used in concert with access controls
toidentify and provide information about users suspected of
impropermodification of data (e.g., introducing errors into a database). An
audittrail may record "before" and "after" versions of records. (Depending
upon
the size of the fi le and the capabilities of the audit logging tools, thismay
be very resource -intensive.) Comparisons can then be made between
theactual changes made to records and what was expected. This can
helpmanagement determine if errors were made by the user, by t he system
orapplication software, or by some other source.
Audit trails work in concert with logical access controls, which restrictuse
of system resources. Granting users access to particular resourcesusually
means that they need that access to accomplis h their job.
Authorized access, of course, can be misused, which is where audit
trailanalysis is useful. While users cannot be prevented from using
resourcesto which they have legitimate access authorization, audit trail
analysis isused to examine their a ctions. For example, consider a
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40 which users have access to those personnel records for which they
areresponsible. Audit trails can reveal that an individual is printing
farmore records than the average user, which could indicate the s elling
ofpersonal data. Another example may be an engineer who is using a
computerfor the design of a new product. Audit trail analysis could reveal
that anoutgoing modem was used extensively by the engineer the week
beforequitting. This could be used t o investigate whether proprietary data
fileswere sent to an unauthorized party.
Reconstruction of Events
Audit trails can also be used to reconstruct events after a problem
hasoccurred. Damage can be more easily assessed by reviewing audit
trails ofsyst em activity to pinpoint how, when, and why normal operations
ceased.Audit trail analysis can often distinguish between operator -induced
errors
(during which the system may have performed exactly as instructed)
orsystem -created errors (e.g., arising from a poorly tested piece
ofreplacement code). If, for example, a system fails or the integrity of
afile (either program or data) is questioned, an analysis of theaudit trail
can reconstruct the series of steps taken by the system, theusers, and the
application . Knowledge of the conditions that existed atthe time of, for
example, a system crash, can be useful in avoiding futureoutages.
Additionally, if a technical problem occurs (e.g., the corruptionof a data
file) audit trails can aid in the recovery process (e.g., byusing the record of
changes made to reconstruct the file).
Intrusion Detection
Intrusion detection refers to the process of identifying attempts topenetrate
a system and gain unauthorized access. If audit trails have beendesigned
and implemente d to record appropriate information, they can assistin
intrusion detection. Although normally thought of as a real -time
effort, intrusions can be detected in real time, by examining audit
recordsas they are created (or through the use of other kinds of
warningflags/notices), or after the fact (e.g., by examining audit records in
abatch process).
Real-time intrusion detection is primarily aimed at outsiders attempting to
gain unauthorized access to the system. It may also be used to
detectchanges in the system's performance indicative of, for example, a
virus orworm attack (forms of malicious code). There may be difficulties
inimplementing real -time auditing, including unacceptable system
performance.
After -the-fact identification may indicate that unaut horized access
wasattempted (or was successful). Attention can then be given to
damageassessment or reviewing controls that were attacked.
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41 Problem Analysis
Audit trails may also be used as on -line tools to help identify
problemsother than intrusions as they occur. This is often referred to
asreal -time auditing or monitoring. If a system or application is deemed
tobe critical to an organization's business or mission, real -time
auditingmay be implemented to monitor the status of these processes
(althoug h, asnoted above, there can be difficulties with real -time analysis).
Ananalysis of the audit trails may be able to verify that the system
operatednormally (i.e., that an error may have resulted from operator error,
asopposed to a
system -originated error) . Such use of audit trails may be complemented
bysystem performance logs. For example, a significant increase in the use
ofsystem resources (e.g., disk file space or outgoing modem use)
couldindicate a security problem.
AUDIT TRAILS AND LOGS
A system ca n maintain several different audit trails concurrently.
Thereare typically two kinds of audit records, (1) an event -oriented log
and (2)a record of every keystroke, often called keystroke
monitoring.Event -based logs usually contain records describing syst em
events,application events, or user events.
An audit trail should include sufficient information to establish whatevents
occurred and who (or what) caused them. In general, an event
recordshould specify when the event occurred, the user ID associated with
the event, the program or command used to initiate the event, and the
result.
Date and time can help determine if the user was a masquerade or
theactual person specified.
3.2.7 IDS (Intrusion Detection Systems)
An intrusion detection system (IDS) is a device, typically another separate
computer, that monitors activity to identify malicious or suspicious events.
Kemmerer and Vigna [KEM02] survey the history of IDSs. An IDS is a
sensor, like a smoke detector, that raises an alarm if specific things occ ur.
A model of an IDS is shown in. The components in the figure are the four
basic elements of an intrusion detection system, based on the Common
Intrusion Detection Framework of [STA96]. An IDS receives raw inputs
from sensors. It saves those inputs, anal yzes them, and takes some
controlling action.
IDSs perform a variety of functions:
 monitoring users and system activity
 auditing system configuration for vulnerabilities and misconfigurations
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42  recognizing known attack patterns in system activity
 identifying abnormal activity through statistical analysis
 managing audit trails and highlighting user violation of policy or
normal activity
 correcting system configuration errors
 installing and operati ng traps to record information about intruders
Types of IDSs
The two general types of intrusion detection systems are signature based
and heuristic .
Signature -based intrusion detection systems perform simple pattern -
matching and report situations that mat ch a pattern corresponding to a
known attack type.
Heuristic intrusion detection systems, also known as anomaly based, build
a model of acceptable behavior and flag exceptions to that model; for the
future, the administrator can mark a flagged behavior as acceptable so that
the heuristic IDS will now treat that previously unclassified behavior as
acceptable. Intrusion detection devices can be network based or host
based. A network -based IDS is a stand -alone device attached to the
network to monitor traffic throughout that network; a host -based IDS runs
on a single workstation or client or host, to protect that one host.
3.2.8 Signature -Based Intrusion Detection
A simple signature for a known attack type might describe a series of TCP
SYN packets sent to man y different ports in succession and at times close
to one another, as would be the case for a port scan. An intrusion detection
system would probably find nothing unusual in the first SYN, say, to port
80, and then another (from the same source address) to port 25. But as
more and more ports receive SYN packets, especially ports that are not
open, this pattern reflects a possible port scan. Similarly, some
implementations of the protocol stack fail if they receive an ICMP packet
with a data length of 65535 bytes, so such a packet would be a pattern for
which to watch.
The problem with signature -based detection is the signatures themselves.
An attacker will try to modify a basic attack in such a way that it will not
match the known signature of that attack. F or example, the attacker may
convert lowercase to uppercase letters or convert a symbol such as "blank
space" to its character code equivalent %20. The IDS must necessarily
work from a canonical form of the data stream in order to recognize that
%20 matche s a pattern with a blank space. The attacker may insert
malformed packets that the IDS will see, to intentionally cause a pattern
mismatch; the protocol handler stack will discard the packets because of
the malformation. Each of these variations could be d etected by an IDS,
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43 Of course, signature -based IDSs cannot detect a new attack for which a
signature is not yet installed in the database. Every attack type starts as a
new pattern at some time, and the IDS is helpless to warn of its existence.
Signature -based intrusion detection systems tend to use statistical analysis.
This approach uses statistical tools both to obtain sample measurements of
key indicators (such as amount of external activity, number of active
processes, number of transactions) and to determine whether the collected
measurements fit the predetermined attack signatures. Ideally, signatures
should match every instance of an attack, match subtle variations of the
attack, but not match traffic that is not part of an attack. However, this
goal is grand but unreachable.

3.2.9 Heuristic Intrusion Detection (Anomaly based)
Because signatures are limited to specific, known attack patterns, another
form of intrusio n detection becomes useful. Instead of looking for
matches, heuristic intrusion detection looks for behavior that is out of the
ordinary. The original work in this area (for example, [TEN90]) focused
on the individual, trying to find characteristics of tha t person that might be
helpful in understanding normal and abnormal behavior. For example, one
user might always start the day by reading e -mail, write many documents
using a word processor, and occasionally back up files. These actions
would be normal.
This user does not seem to use many administrator utilities. If that person
tried to access sensitive system management utilities, this new behavior
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44 we think of a compromised system in use, it starts clean, with no intrusion,
and it ends dirty, fully compromised. There may be no point in the trace of
use in which the system changed from clean to dirty; it was more likely
that little dirty events occurred, occasionally at first and the n increasing as
the system became more deeply compromised.
Any one of those events might be acceptable by itself, but the
accumulation of them and the order and speed at which they occurred
could have been signals that something unacceptable was happening . The
inference engine of an intrusion detection system performs continuous
analysis of the system, raising an alert when the system's dirtiness exceeds
a threshold. Inference engines work in two ways. Some, called state -based
intrusion detection systems, see the system going through changes of
overall state or configuration.
They try to detect when the system has veered into unsafe modes. Others
try to map current activity onto a model of unacceptable activity and raise
an alarm when the activity resemble s the model. These are called model -
based intrusion detection systems. This approach has been extended to
networks in [MUK94]. Later work (for example, [FOR96, LIN99]) sought
to build a dynamic model of behavior, to accommodate variation and
evolution in a person's actions over time. The technique compares real
activity with a known representation of normality. Alternatively, intrusion
detection can work from a model of known bad activity. For example,
except for a few utilities (login, change password, cre ate user), any other
attempt to access a password file is suspect. This form of intrusion
detection is known as misuse intrusion detection. In this work, the real
activity is compared against a known suspicious area.
All heuristic intrusion detection acti vity is classified in one of three
categories: good/benign, suspicious, or unknown. Over time, specific
kinds of actions can move from one of these categories to another,
corresponding to the IDS's learning whether certain actions are acceptable
or not. As with pattern -matching, heuristic intrusion detection is limited by
the amount of information the system has seen (to classify actions into the
right category) and how well the current actions fit into one of these
categories.
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45 3.2.10 IPS (Intrusion Preve ntion System)
An Intrusion Prevention System (IPS) is a network security/threat
prevention technology that examines network traffic flows to detect and
prevent vulnerability exploits. Vulnerability exploits usually come in the
form of malicious inputs to a target application or service that attackers
use to interrupt and gain control of an application or machine. Following a
successful exploit, the attacker can disable the target application (resulting
in a denial -of-service state), or can potentially acces s to all the rights and
permissions available to the compromised application.
The IPS often sits directly behind the firewall and provides a
complementary layer of analysis that negatively selects for dangerous
content. Unlike its predecessor the Intrusion Detection System (IDS) —
which is a passive system that scans traffic and reports back on threats —
the IPS is placed inline (in the direct communication path between source
and destination), actively analyzing and taking automated actions on all
traffic flow s that enter the network. Specifically, these actions include:
 Sending an alarm to the administrator (as would be seen in an IDS)
 Dropping the malicious packets
 Blocking traffic from the source address
 Resetting the connection
As an inline security compone nt, the IPS must work efficiently to avoid
degrading network performance. It must also work fast because exploits
can happen in near real -time. The IPS must also detect and respond
accurately, so as to eliminate threats and false positives (legitimate pack ets
misread as threats).
3.2.11 policy -based detection
policy -based detection in which the IPS first requires administrators to
make security policies -- when an event occurs that breaks a defined
security policy, an alert is sent to system administrators.
If any threats are detected, an IPS tool is typically capable of sending
alerts to the administrator, dropping any malicious network packets, and
resetting connections by reconfiguring firewalls, repackaging payloads
and removing infected attachments from servers.
IPS tools can help fend off denial -of-service (DoS) attacks, distributed
denial -of-service (DDoS) attacks, worms, viruses or exploits, such as
a zero-day exploit. According to Michael Reed, formerly of Top Layer
Networks (acquired by Corero), an effective intrusion prevention system
should perform more complex monitoring and analysis, such as watching
and responding to traffic patterns, as well as individual packets.
"Detection mechanisms can include address matching, HTTP [Hypertext
Transfer Prot ocol] string and substring matching, generic pattern
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46 packet anomaly detection, traffic anomaly detection and TCP/UDP [User
Datagram Protocol] port matching."

3.2.12 Honeypot based
How do you catch a mouse? You set a trap with bait (food the mouse finds
attractive) and catch the mouse after it is lured into the trap. You can catch
a computer attacker the same way. In a very interesting book, Cliff Stoll
[STO89] details the story of attract ing and monitoring the actions of an
attacker. Cheswick [CHE90, CHE02] and Bellovin [BEL92c] tell a similar
story.
These two cases describe the use of a honeypot: a computer system open
to attackers. 480 480 You put up a honeypot for several reasons: to w atch
what attackers do, in order to learn about new attacks (so that you can
strengthen your defenses against these new attacks) • to lure an attacker to
a place in which you may be able to learn enough to identify and stop the
attacker • to provide an att ractive but diversionary playground, hoping that
the attacker will leave your real system alone • A honeypot has no special
features. It is just a computer system or a network segment, loaded with
servers and devices and data. It may be protected with a fi rewall, although
you want the attackers to have some access. There may be some
monitoring capability, done carefully so that the monitoring is not evident
to the attacker. The two difficult features of a honeypot are putting up a
believable, attractive fal se environment and confining and monitoring the
attacker surreptitiously.
Spitzner [SPI02, SPI03a] has done extensive work developing and
analyzing honeypots. He thinks like the attacker, figuring what the
attacker will want to see in an invaded computer, but as McCarty
[MCC03] points out, it is always a race between attacker and defender.
Spitzner also tries to move much of his data off the target platform so that
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47 modify or erase the data gathered. Raynal [RAY04a. RAY04b] discusses
how to analyze the data collected.

3.3 WEB SERVER SECURITY
Web server security refers to the tools, technologies and processes that
enable information security (IS) on a Web server. This broad term
encompasses all processes that ensure that a working Internet server
operates under a security policy.
Web server security is the security of any server that is deployed on a
Worldwide Web domain or the Internet. It is implemented through several
methods and in layers, typically, including the base operating system (OS)
security layer, hosted application security layer and network security
layer. OS security, which ensures access to authorized users only, operates
a Web server’s critical components and service s. Application layer
security ensures control over the content and services hosted on the Web
server. Network security provides protection against Internet -based
security exploits, viruses and attacks.
Secure Sockets Layer (SSL) certificates, HTTP Secur e protocol and
firewalling are several tools and technologies used to implement Web
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48 3.3.1 SSL ( Secure Sockets Layer)
The SSL (Secure Sockets Layer) protocol was originally designed by
Netscape to protect communication between a web brow ser and server. It
is also known now as TLS, for transport layer security. SSL interfaces
between applications (such as browsers) and the TCP/IP protocols to
provide server authentication, optional client authentication, and an
encrypted communications cha nnel between client and server. Client and
server 467 467 negotiate a mutually supported suite of encryption for
session encryption and hashing; possibilities include triple DES and
SHA1, or RC4 with a 128 -bit key and MD5. To use SSL, the client
requests a n SSL session. The server responds with its public key
certificate so that the client can determine the authenticity of the server.
The client returns part of a symmetric session key encrypted under the
server's public key. Both the server and client compu te the session key,
and then they switch to encrypted communication, using the shared
session key. The protocol is simple but effective, and it is the most widely
used secure communication protocol on the Internet. However, remember
that SSL protects only from the client's browser to the server's decryption
point (which is often only to the server's firewall or, slightly stronger, to
the computer that runs the web application). Data are exposed from the
user's keyboard to the browser and throughout the reci pient's company.
Blue Gem Security has developed a product called LocalSSL that encrypts
data after it has been typed until the operating system delivers it to the
client's browser, thus thwarting any keylogging Trojan horse that has
become implanted in th e user's computer to reveal everything the user
types.
provides security to the data that is transferred between web browser and
server. SSL encrypts the link between a web server and a browser which
ensures that all data passed between them remain private and free from
attack.
Secure Socket Layer Protocols:
 SSL record protocol
 Handshake protocol
 Change -cipher spec protocol
 Alert protocol
SSL Protocol Stack:
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49 SSL Record Protocol:
SSL Record provides two services to SSL connection.
 Confidentiality
 Mess age Integrity
In the SSL Record Protocol application data is divided into fragments.
The fragment is compressed and then encrypted MAC (Message
Authentication Code) generated by algorithms like SHA (Secure Hash
Protocol) and MD5 (Message Digest) is appende d. After that encryption
of the data is done and in last SSL header is appended to the data.

Handshake Protocol:
Handshake Protocol is used to establish sessions. This protocol allows
the client and server to authenticate each other by sending a series of
messages to each other. Handshake protocol uses four phases to
complete its cycle.
 Phase -1: In Phase -1 both Client and Server send hello -packets to
each other. In this IP session, cipher suite and protocol version are
exchanged for security purposes.
 Phase -2: Server sends his certificate and Server -key-exchange. The
server end phase -2 by sending the Server -hello -end packet.
 Phase -3: In this phase Client reply to the server by sending his
certificate and Client -exchange -key.
 Phase -4: In Phase -4 Chang e-cipher suite occurred and after this
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50 Change -cipher Protocol:
This protocol uses the SSL record protocol. Unless Handshake Protocol
is completed, the SSL record Output will be in a pending state. After
handshake protocol, the Pendi ng state is converted into the current state.
Change -cipher protocol consists of a single message which is 1 byte in
length and can have only one value. This protocol’s purpose is to cause
the pending state to be copied into the current state.
Alert Prot ocol:
This protocol is used to convey SSL -related alerts to the peer entity.
Each message in this protocol contains 2 bytes.
The level is further classified into two parts:
 Warning:
This Alert has no impact on the connection between sender and
receiver.
 Fatal Error:
 This Alert breaks the connection between sender and receiver.
 Silent Features of Secure Socket Layer:
The advantage of this approach is that the service can be tailored to
the specific needs of the given application.
 Secure Socket Laye r was originated by Netscape.
 SSL is designed to make use of TCP to provide reliable end -to-end
secure service.
 This is a two -layered protocol.
3.3.2 TLS (Transport Layer Security)
Transport Layer Security (TLS), the successor of the now -deprecated
Secure Sockets Layer (SSL), is a cryptographic protocol designed to
provide communications security over a computer network. The protocol
is widely used in applications such as email, instant messaging, and voice
over IP, but its use as the Security layer in HTTP S remains the most
publicly visible.
The TLS protocol aims primarily to provide privacy and data integrity
between two or more communicating computer applications. It runs in the
application layer of the Internet and is itself composed of two layers: the
TLS record and the TLS handshake protocols.
TLS is a proposed Internet Engineering Task Force (IETF) standard, first
defined in 1999, and the current version is TLS 3.3 defined in August
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51 developed by Netscape Communications for adding the HTTPS protocol
to their Navigator web browser.
Client -server applications use the TLS protocol to communicate across a
network in a way designed to prevent eavesdropping and tampering .
Since applications can communicate either with or without TLS (or SSL),
it is necessary for the client to request that the server sets up a TLS
connection.[1] One of the main ways of achieving this is to use a
different port number for TLS connections. For example, port 80 is
typically used for unencrypted HTTP traffic while port 443 is the common
port used for encrypted HTTPS traffic. Another mechanism is for the
client to make a protocol -specific request to the server to switch the
connection to TLS; for example, by making a STARTTLS request when
using the mail and news protocols.
Once the client a nd server have agreed to use TLS, they negotiate
a stateful connection by using a handshaking procedure.[2] The protocols
use a handshake with an asymme tric cipher to establish not only cipher
settings but also a session -specific shared key with which further
communication is encrypted using a symmetric cipher . During this
handshake, the client and server agree on various parameters used to
establish the connection's security:
 The handshake begins when a client connects to a TLS -enabled server
requesting a secure connection and the client presents a list of
supported cipher suites (ciphers and hash functions ).
 From this list, the server picks a cipher and hash function that it also
supports and notifies the client of the decision.
 The server usually then provides identification in the form of a digital
certificate . The certificate contains the server name , the
trusted certificate authority (CA) that vouches for the authenticity of
the certificate, and the server's public encryption key.
 The client confirms the validity of the certificate before proceeding.
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52 3.3.3 Client Authenti cation
Client Authentication is the process by which users securely access a
server or remote computer by exchanging a Digital Certificate . The
Digital Certificate is in part seen as your 'Digital ID' and is used to
cryptographically bind a customer, emplo yee, or partner's identity to a
unique Digital Certificate (typically including the name, company name
and location of the Digital Certificate owner). The Digital Certificate can
then be mapped to a user account and used to provide access control to
networ k resources, web services and websites.
Just as organizations need to control which individual users have access to
corporate networks and resources, they also need to be able to identify and
control which machines and servers have access. Implementing dev ice
authentication means only machines with the appropriate credentials can
access, communicate, and operate on corporate networks.
Organizations can leverage the registry information stored in Active
Directory to automatically issue template -based and opt ionally configured
certificates to all machines and servers residing within a single domain, or
multiple domains in a single or multiple forest configuration.
The Digital Certificates used for client and device authentication may look
the same as any other Digital Certificate that you may already be using
within your organization, such as certificates for securing web services
(SSL) or email/document signatures (digital signatures), but Digital
Certificates are likely to have a few different properties depe nding on the
use.
Client authentication can be used to prevent unauthorized access, or
simply to add a second layer of security to your current username and
password combination. Client authentication and access control also
enables organizations to meet r egulatory and privacy compliancy, as well
as fulfil internal security policies using PKI -based two -factor
authentication – 'something you have' (a GlobalSign Digital Certificate)
and 'something you know' (an internally managed password).
Client authenticat ion has multiple benefits as an authentication method
especially when compared to the basic username and password method:
 You can decide whether or not a user is required to enter a username
and password
 Encrypts transactions over the network, identifies t he server and
validates any messages sent
 Validates the user identity using a trusted party (the Certificate
Authority) and allows for centralized management of certificates
which enables easy revocation
 Optional - you can configure the certificate so it c annot be exported to
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53  Restrict access by user, group, roles, or device based on Active
Directory (using GlobalSign's Auto Enrolment Gateway (AEG)
solution)
 Serves more purposes than authentic ation such as integrity and
confidentiality
 Prevents malicious attacks/problems, including but not limited to
phishing, keystroke logging and man -in-the-middle (MITM) attacks

3.3.4 PKI (Public Key Infrastructure)
A public key infrastructure (PKI) is a se t of roles, policies, hardware,
software and procedures needed to create, manage, distribute, use, store
and revoke digital certificates and manage public -key encryption. The
purpose of a PKI is to facilitate the secure electronic transfer of
information f or a range of network activities such as e -commerce, internet
banking and confidential email. It is required for activities where simple
passwords are an inadequate authentication method and more rigorous
proof is required to confirm the identity of the pa rties involved in the
communication and to validate the information being transferred.
In cryptography, a PKI is an arrangement that binds public keys with
respective identities of entities (like people and organizations). The
binding is established throug h a process of registration and issuance of
certificates at and by a certificate authority (CA). Depending on the
assurance level of the binding, this may be carried out by an automated
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54 requires using a secure certificate enrolment or certificate management
protocol such as CMP.
The PKI role that may be delegated by a CA to assure valid and correct
registration is called a registration authority (RA). Basically, an RA is
responsible for acce pting requests for digital certificates and
authenticating the entity making the request.[1] The Internet Engineering
Task Force's RFC 3647 defines an RA as " An entity that is responsible for
one or more of the following functions: the identification and
authentication of certificate applicants, the approval or rejection of
certificate applications, initiating certificate revocations or suspensions
under certai n circumstances, processing subscriber requests to revoke or
suspend their certificates, and approving or rejecting requests by
subscribers to renew or re -key their certificates. RAs, however, do not sign
or issue certificates (i.e., an RA is delegated cer tain tasks on behalf of a
CA).While Microsoft may have referred to a subordinate CA as an
RA,[3] this is incorrect according to the X.509 PKI standards. RAs do not
have the signing authority of a CA and only manage the vetting and
provisioning of certificates. So in the Microsoft PKI case, the RA
functionality is provided either by the Microsoft Certificate Services web
site or through Active Directory Certificate Se rvices which enforces
Microsoft Enterprise CA and certificate policy through certificate
templates and manages certificate enrollment (manual or auto -enrollment).
In the case of Microsoft Standalone CAs, the function of RA does not
exist since all of the p rocedures controlling the CA are based on the
administration and access procedure associate with the system hosting the
CA and the CA itself rather than Active Directory. Most non -Microsoft
commercial PKI solutions offer a stand -alone RA component.
An enti ty must be uniquely identifiable within each CA domain on the
basis of information about that entity. A third -party validation
authority (VA) can provide this entity information on behalf of the CA.

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55 3.3.5 Encoding
Encoding is defined as the process of c onverting data from one form to
another and has nothing to do with cryptography. It guarantees none of
the 3 cryptographic properties of confidentiality, integrity, and
authenticity because it involves no secret and is completely reversible.
Encoding metho ds are considered public and are used for data
handling . For example, data transmitted over the Internet require a
specific format and URL -encoding our data will allow us to transmit
them over the Internet. Similarly, in an HTML context, HTML -
encoding our data is needed to adhere to the required HTML character
format. Another popular encoding algorithm is base64. Base64 encoding
is commonly used to encode binary data that need to be stored or
transferred in media which are designed to process textual data. The
examples above aim to point out that encoding’s use case is only data
handling and provides no protection for the encoded data.
In the Encoding method, data is transformed from one form to another.
The main aim of encoding is to transform data into a f orm that is
readable by most of the systems or that can be used by any external
process. It can’t be used for securing data, various publicly available
algorithms are used for encoding.
Encoding can be used for reducing the size of audio and video files. E ach
audio and video file format has a corresponding coder -decoder (codec)
program that is used to code it into the appropriate format and then
decodes for playback.
Encoding data is a process involving changing data into a new format
using a scheme. Encodi ng is a reversible process; data can be encoded to a
new format and decoded to its original format. Encoding typically
involves a publicly available scheme that is easily reversed. Encoding data
is typically used to ensure integrity and usability of data a nd is commonly
used when data cannot be transferred in its current format between
systems or applications.
Encoding is not used to protect or secure data because it is easy to reverse.
An example of encoding is: Base64
Take a scenario where a user wants to upload a resume to a job application
website and the web server stores.
3.3.6 Secure Electronic Transaction (SET
Secure Electronic Transaction or SET is a system that ensures the
security and integrity of electronic transactions done using credit cards in
a scenario. SET is not some system that enables payment but it is a
security protocol applied to those payments. It uses different encryption
and hashing techniques to secure payments over the internet done
through credit cards. The SET protocol was suppo rted in development by
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56 Secure Transaction Technology (STT), and Netscape which provided the
technology of Secure Socket Layer (SSL).
SET protocol restricts the revealing of credit car d details to merchants
thus keeping hackers and thieves at bay. The SET protocol includes
Certification Authorities for making use of standard Digital Certificates
like X.509 Certificate.
Before discussing SET further, let’s see a general scenario of elec tronic
transactions, which includes client, payment gateway, client financial
institution, merchant, and merchant financial institution.
Requirements in SET :
The SET protocol has some requirements to meet, some of the important
requirements are :
 It has to provide mutual authentication i.e., customer (or cardholder)
authentication by confirming if the customer is an intended user or
not, and merchant authentication.
 It has to keep the PI (Payment Information) and OI (Order
Information) confidential by ap propriate encryptions.
 It has to be resistive against message modifications i.e., no changes
should be allowed in the content being transmitted.
 SET also needs to provide interoperability and make use of the best
security mechanisms.
Participants in SET :
In the general scenario of online transactions, SET includes similar
participants:

1. Cardholder – customer
2. Issuer – customer financial institution
3. Merchant
4. Acquirer – Merchant financial
5. Certificate authority – Authority that follows certain standards and
issues certificates(like X.509V3) to all other participants.
SET functionalities :
 Provide Authentication
 Merchant Authentication – To prevent theft, SET allows customers
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57 institutions. Standa rd X.509V3 certificates are used for this
verification.
 Customer / Cardholder Authentication – SET checks if the use of
a credit card is done by an authorized user or not using X.509V3
certificates.
 Provide Message Confidentiality : Confidentiality refers t o
preventing unintended people from reading the message being
transferred. SET implements confidentiality by using encryption
techniques. Traditionally DES is used for encryption purposes.
 Provide Message Integrity : SET doesn’t allow message
modification w ith the help of signatures. Messages are protected
against unauthorized modification using RSA digital signatures with
SHA -1 and some using HMAC with SHA -1,
Dual Signature :
The dual signature is a concept introduced with SET, which aims at
connecting two information pieces meant for two different receivers :
Order Information (OI) for merchant Payment Information (PI) for
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58 3.3.7 Kerberos
Kerberos is a system that supports authentication in distributed systems.
Originally designed to work wit h secret key encryption, Kerberos, in its
latest version, uses public key technology to support key exchange. The
Kerberos system was designed at Massachusetts Institute of Technology
[STE88, KOH93]. Kerberos is used for authentication between intelligent
processes, such as client -to-server tasks, or a user's workstation to other
hosts. Kerberos is based on the idea that a central server provides
authenticated tokens, called tickets, to requesting applications.
A ticket is an unforgeable, nonrepayable, aut henticated object. That is, it is
an encrypted data structure naming a user and a service that user is
allowed to obtain. It also contains a time value and some control
information.
Here are the principal entities involved in the typical Kerberos workflow :
 Client. The client acts on behalf of the user and initiates
communication for a service request
 Server. The server hosts the service the user wants to access
 Authentication Server (AS). The AS performs the desired client
authentication. If the authentica tion happens successfully, the AS
issues the client a ticket called TGT (Ticket Granting Ticket). This
ticket assures the other servers that the client is authenticated
 Key Distribution Center (KDC). In a Kerberos environment, the
authentication server log ically separated into three parts: A database
(db), the Authentication Server (AS), and the Ticket Granting Server
(TGS). These three parts, in turn, exist in a single server called the Key
Distribution Center
 Ticket Granting Server (TGS). The TGS is an ap plication server that
issues service tickets as a serviceirst, there are three crucial secret keys
involved in the Kerberos flow. There are unique secret keys for the
client/user, the TGS, and the server shared with the AS.
 Client/user. Hash derived from t he user's password
 TGS secret key. Hash of the password employed in determining the
TGS
 Server secret key. Hash of the password used to determine the server
providing the service.
The protocol flow consists of the following steps:
Step 1: Initial client au thentication request. The user asks for a Ticket
Granting Ticket (TGT) from the authentication server (AS). This request
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59 Step 2: KDC verifies the client's credentials. The AS checks the database
for the client and TGS's availability . If the AS finds both values, it
generates a client/user secret key, employing the user's password hash.
The AS then computes the TGS secret key and creates a session key (SK1)
encrypted by the client/user secret key. The AS then generates a TGT
containin g the client ID, client network address, timestamp, lifetime, and
SK3. The TGS secret key then encrypts the ticket.
Step 3: The client decrypts the message. The client uses the client/user
secret key to decrypt the message and extract the SK1 and TGT,
gene rating the authenticator that validates the client's TGS.
Step 4: The client uses TGT to request access. The client requests a ticket
from the server offering the service by sending the extracted TGT and the
created authenticator to TGS.
Step 5: The KDC cr eates a ticket for the file server. The TGS then uses the
TGS secret key to decrypt the TGT received from the client and extracts
the SK 3. The TGS decrypts the authenticator and checks to see if it
matches the client ID and client network address. The TGS also uses the
extracted timestamp to make sure the TGT hasn't expired.
If the process conducts all the checks successfully, then the KDC
generates a service session key (SK2) that is shared between the client and
the target server.
Finally, the KDC creates a service ticket that includes the client id, client
network address, timestamp, and SK2. This ticket is then encrypted with
the server's secret key obtained from the db. The client receives a message
containing the service ticket and the SK2, all encrypt ed with SK 3.
Step 6: The client uses the file ticket to authenticate. The client decrypts
the message using SK1 and extracts SK2. This process generates a new
authenticator containing the client network address, client ID, and
timestamp, encrypted with SK2 , and sends it and the service ticket to the
target server.
Step 7: The target server receives decryption and authentication. The
target server uses the server's secret key to decrypt the service ticket and
extract the SK2. The server uses SK2 to decrypt the authenticator,
performing checks to make sure the client ID and client network address
from the authenticator and the service ticket match. The server also checks
the service ticket to see if it's expired.
Once the checks are met, the target server sen ds the client a message
verifying that the client and the server have authenticated each other. The
user can now engage in a secure session.

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3.4 LET US SUM UP
Network security is any activity designed to protect the usability and
integrity of your netw ork and data.
 It includes both hardware and software technologies
 It targets a variety of threats
 It stops them from entering or spreading on your network
 Effective network security manages access to the network
 A firewall is a network security device that monitors incoming and
outgoing network traffic and decides whether to allow or block
specific traffic based on a defined set of security rules.
 A firewall can be hardware, software, or both
3.5 LIST OF REFERENCES
A. http://www.ijmer.com/papers/Vol8_issue12/D0812012327.pdf
B. https://dokumen.tips/download/link/security -in-computing -4th-edition -
2006#google_vignette
C. https://www.cisco.com/c/en_in/products/security/firewalls/what -is-a-
firewall.html
3.6 SUMMARY
Network security helps in protecting the network and data from violation,
intrusions and other threats. It is the most critical one because it prevents
from cybercriminals from gaining the access to sensitive and valuable
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61 3.7 BIBLIOGRAPHY
A. dokumen.tips_security -in-computing -4th-edition -2006.pdf
B. Network Security, Charlie Kaufman, Radia Perlam, Mike Speciner,
Prentice Hall, 2nd Edition (2002)
C. Cryptography and Network Security 3rd edition, Atul Kahate, Tata
McGraw Hill Education Private Limited (2013)
3.8 UNIT END EXERCISE
1. Number of phases in the handshaking protocol?
a) 2
b) 3
c) 4
d) 5
2. Which one of the following is not a higher –layer SSL protocol?
a) Alert Protocol
b) Handshake Protocol
c) Alarm Protocol
d) Change Cipher Spec Protocol
3. The full form of SSL is
a) Serial Session L ayer
b) Secure Socket Layer
c) Session Secure Layer
d) Series Socket Layer
4. Which of the following is not a secure shell protocol?
a) Transport Layer Protocol
b) Secure Layer Protocol
c) Connection Protocol
d) User Authentication Protocol
5. Network layer fire wall works as a __________
a) Frame filter
b) Packet filter
c) Content filter
d) Virus filter

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62 6. A firewall is installed at the point where the secure internal network
and untrusted external network meet which is also known as
__________
a) Chock point
b) Me eting point
c) Firewall point
d) Secure point
7. What is one advantage of setting up a DMZ with two firewalls?
a) You can control where traffic goes in three networks
b) You can do stateful packet filtering
c) You can do load balancing
d) Improved network per formance
8. What are the different ways to classify an IDS?
a) Zone based
b) Host & Network based
c) Network & Zone based
d) Level based
9. What are the characteristics of anomaly -based IDS?
a) It models the normal usage of network as a noise characterization
b) It doesn’t detect novel attacks
c) Anything distinct from the noise is not assumed to be intrusion
activity
d) It detects based on signature
10. What are the characteristics of signature -based IDS?
a) Most are based on simple pattern matching algorithms
b) It is programmed to interpret a certain series of packets
c) It models the normal usage of network as a noise characterization
d) Anything distinct from the noise is assumed to be intrusion activity
11. What is the major drawback of anomaly detection IDS?
a) The se are very slow at detection
b) It generates many false alarms
c) It doesn’t detect novel attacks
d) None of the mentioned



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63 12. what are the drawbacks of signature -based IDS?
a) They are unable to detect novel attacks
b) They suffer from false alarms
c) They h ave to be programmed again for every new pattern to be
detected
d) All of the mentioned
13. Public key encryption/decryption is not preferred because
a) it is slow
b) it is hardware/software intensive
c) it has a high computational load
d) all of the mentioned
14. ___________ ensures the integrity and security of data that are passing
over a network.
a) Firewall
b) Antivirus
c) Pen testing Tools
d) Network -security protocols
15. TSL (Transport Layer Security) is a cryptographic protocol used for
securing HTTP/HTTPS bas ed connection.
a) True
b) False

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Unit Structure :
4.0 Objectives
4.1 Introduction
4.2 Web server security
4.3 SSL/TLS
4.4 SSL/TLS Basic protocol
4.5 Computing the keys - client authentication
4.6 PKI as deployed by SSL Attacks fixed in v3
4.7 Secure Electronic Tra nsaction (SET)
4.8 Kerberos
4.9 Summary
4.10 References for reading
4.0 OBJECTIVES
1. To understand the basics of web security
2. To understand Kerberos
3. To understand the Basic Protocols
4. To understand the need of Secure Electronic Transaction.
4.1 INTRODUCTION
Network security mainly refers to an evaluation which is taken by any
enterprise or an organization to secure or to make safe its computer
network. Its main role is to maintain confidentiality and accessibility of
the data and network. In every enterprise or an organization which
generally manages or handles a large amount of data needs some infusion
aginst many cyber threats. The most common example of network security
is to handle the password protection. Network security has become the
main subject of cy ber security. Network security deals with various levels
which helps in performing the activities needed for handles the large
amount of data in a secure manner.


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65 4.2 WEB SERVER SECURITY
Web server security is the protection of information assets that can be
accessed from a Web server. Web server security is important for any
organization that has a physical or virtual Web server connected to the
Internet.
4.3 Ssl/Tls [2,3,4]
Secure Socket Layer (SSL) provides security to the data that is
transferred betwee n web browser and server. SSL encrypts the link
between a web server and a browser which ensures that all data passed
between them remain private and free from attack.
Secure Socket Layer Protocols:
 SSL record protocol
 Handshake protocol
 Change -cipher sp ec protocol
 Alert protocol
SSL Protocol Stack:

SSL Record Protocol:
SSL Record provides two services to SSL connection.
 Confidentiality
 Message Integrity
In the SSL Record Protocol application data is divided into fragments.
The fragment is compresse d and then encrypted MAC (Message
Authentication Code) generated by algorithms like SHA (Secure Hash
Protocol) and MD5 (Message Digest) is appended. After that encryption
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66

Handshake Pro tocol:
Handshake Protocol is used to establish sessions. This protocol allows
the client and server to authenticate each other by sending a series of
messages to each other. Handshake protocol uses four phases to
complete its cycle.
 Phase -1: In Phase -1 both Client and Server send hello -packets to
each other. In this IP session, cipher suite and protocol version are
exchanged for security purposes.
 Phase -2: Server sends his certificate and Server -key-exchange. The
server end phase -2 by sending the Server -hello -end packet.
 Phase -3: In this phase, Client replies to the server by sending his
certificate and Client -exchange -key.
 Phase -4: In Phase -4 Change -cipher suite occurred and after this
Handshake Protocol ends.

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67 Change -cipher Protocol:
This protocol uses the SSL record protocol. Unless Handshake Protocol
is completed, the SSL record Output will be in a pending state. After the
handshake protocol, the Pending state is converted into the current state.
Change -cipher protocol consists of a single message which is 1 byte in
length and can have only one value. This protocol’s purpose is to cause
the pending state to be copied into the current state.

Alert Protocol:
This protocol is used to conv ey SSL -related alerts to the peer entity.
Each message in this protocol contains 2 bytes.

The level is further classified into two parts:
Warning (level = 1):
This Alert has no impact on the connection between sender and
receiver. Some of them are:
Bad certificate: When the received certificate is corrupt.
No certificate: When an appropriate certificate is not available.
Certificate expired: When a certificate has expired.
Certificate unknown: When some other unspecified issue arose in
processing the c ertificate, rendering it unacceptable.
Close notify : It notifies that the sender will no longer send any messages
in the connection.
Fatal Error (level = 2):
This Alert breaks the connection between sender and receiver. The
connection will be stopped, can not be resumed but can be restarted.
Some of them are :
Handshake failure: When the sender is unable to negotiate an
acceptable set of security parameters given the options available.
Decompression failure : When the decompression function receives
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68 Illegal parameters: When a field is out of range or inconsistent with
other fields.
Bad record MAC: When an incorrect MAC was received.
Unexpected message: When an inappropriate message is received.
The second byte in the Alert protocol describes t he error.
Silent Features of Secure Socket Layer:
 The advantage of this approach is that the service can be tailored to
the specific needs of the given application.
 Secure Socket Layer was originated by Netscape.
 SSL is designed to make use of TCP to prov ide reliable end -to-end
secure service.
 This is a two -layered protocol.
Versions of SSL:
SSL 1 – Never released due to high insecurity.
SSL 2 – Released in 1995.
SSL 3 – Released in 1996.
TLS 4.0 – Released in 1999.
TLS 4.1 – Released in 2006.
TLS 4.2 – Released in 2008.
TLS 4.3 – Released in 2018.
Transport Layer Securities
Transport Layer Securities (TLS) are designed to provide security at the
transport layer. TLS was derived from a security protocol called Secure
Socket Layer (SSL) . TLS ensures that no third party may eavesdrop or
tampers with any message.
There are several benefits of TLS:
Encryption:
TLS/SSL can help to secure transmitted data using encryption.
 Interoperability:
TLS/SSL works with most web browsers, including Microsoft
Internet Ex plorer and on most operating systems and web servers.

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69  Algorithm flexibility:
TLS/SSL provides operations for authentication mechanism,
encryption algorithms and hashing algorithm that are used during the
secure session.
 Ease of Deployment:
Many applicati ons TLS/SSL temporarily on a windows server 2003
operating systems.
 Ease of Use:
Because we implement TLS/SSL beneath the application layer, most
of its operations are completely invisible to client.
Working of TLS:
The client connect to server (using TCP), the client will be something.
The client sends number of specification:
1. Version of SSL/TLS.
2. which cipher suites, compr ession method it wants to use.
The server checks what the highest SSL/TLS version is that is supported
by them both, picks a ciphe r suite from one of the clients option (if it
supports one) and optionally picks a compression method. After this the
basic setup is done, the server provides its certificate. This certificate
must be trusted either by the client itself or a party that the client trusts.
Having verified the certificate and being certain this server really is who
he claims to be (and not a man in the middle), a key is exchanged. This
can be a public key, “PreMasterSecret” or simply nothing depending
upon cipher suite.
Both the server and client can now compute the key for symmetric
encryption. The handshake is finished and the two hosts can
communicate securely. To close a connection by finishing. TCP
connection both sides will know the connection was improperly
terminated. The connection cannot be compromised by this through,
merely interrupted.
4.4 SSL/TLS BASIC PROTOCOL [2,3,4]
SSL stands for Secure Sockets Layer and was originally created by
Netscape. SSLv2 and SSLv3 are the 2 versions of this protocol (SSLv1
was never pub licly released). After SSLv3, SSL was renamed to TLS.
TLS stands for Transport Layer Security and started with TLSv 4.0 which
is an upgraded version of SSLv3.
Those protocols are standardized and described by RFCs.
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70 OpenSSL provides an implementation for tho se protocols and is often
used as the reference implementation for any new feature.
The goal of SSL was to provide secure communication using classical
TCP sockets with very few changes in API usage of sockets to be able to
leverage security on existing TC P socket code.
SSL/TLS is used in every brows er worldwide to provide https (http
secure ) functionality.
4.5 COMPUTING THE KEYS - CLIENT
AUTHENTICATION
Server Authentication
Server Certificate
This is Public Key Certified by a Certificate with Trust fro m the client.
Trust from the client can be done automatically with Certificate Authority
trust.
It is crucial that clients check the Server Certificate against the expected
hostname Hostname_validation
No Authentication Aka Anonymous
Even if it look like i s a strange idea, it is possible to select cipher suite that
does not provide any server authentication but still provide confidentiality.
Selecting string cipher aNULL Manual:ciphers allows to select such
cipher suite. Remark this is not same a eNULL that provides no
confidentiality at all.
Anonymous Diffie_Hellman exchange ( DH) and Anonymous Elliptic
Curves Diffie Hellman Exchange ( ECDH ) methods provide this
anonymous authentication.
Client Authentication
Client authentication is optional. In many cases t he client does not
authenticate at the ssl layer, but rather with the usage of protocols above
ssl, for example with HTTP authentication methods.
Client Certificates
 Certificate Request TLS v 4.2
Server can send a Certificate Request with digest algorithms and a list CA
Distinguished names which will be used by the client to select the Client
Certificate it will send.
 Client Certificate TLS v 4.2
Client send its Client Certificate first then all intermediate Certificates, if
any, up to the CA ( optionally exc luded ).
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71 The Client sends a Certificate Verify that is signed by the private key
counterpart of its Client public key included in the Certificate with digest
algorithm over whole handshake messages so far ( excluding this one of
course ).
This proves that this client owns the private key that applies to this
specific handshake and hence authenticates the client for this session.
Alternate Authentication Methods
Public Key Certificate
This is the most commonly used method. With X50 9 Certificates and
Certficate Authorities.
It applies To Server Certificate or to Client Certificate authentication.
Depending on CipherSuite, for Server Public Key can be used to derive
pre-master -key.
Pre-Shared Keys
TLS PSK Pre Shared Key
Kerberos
Passw ord
TLS SRP : Secure Remote Password. Allows authentication with a
password over TLS.
Supported by OpenSSL with version 4.0.4.
RFC5054
TLS SRP is negotiated with various ciphersuites, currently all use SHA to
compute SRP.
With SRP trust is based on the fac t that both parties should know the
password ( or Password Verifier ) to complete the SRP Verify Handshake.
It is possible to use RSA or DSS additionaly to prove Server identity with
Certificates.
4.6 PKI AS DEPLOYED BY SSL ATTACKS FIXED IN
V3 - [1 - 4]
In the real world, when we want to make sure a service is honest and
delivers us the promised goods we ask for some sort of “seal of trust”.
That “seal of trust” usually comes in the form of a certificate signed by a
trusted notary that vouches for the leg itimacy and honesty of that provider.
For that model to work, both the business and the consumer need to trust
that notary.
The virtual world works in a similar fashion through an infrastructure
called PKI. When we log onto a Web site, say a bank, the bro wser first
requests the site provide it with a certificate guaranteeing that the site is
what it appears to be. That certificate is “signed” by the digital equivalent
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72 The certificate does not only guara ntee the authenticity of the service, but
also the confidentiality of communications between the user and the
service. It does this by supplying the required components used to encrypt
our transactions. Through the use of encryption, the protocol is able t o
guarantee the privacy and security of the transactions because it prevents
some third party to eavesdrop or modify the transactions. The most
popular method of encryption for these transactions is, generally speaking,
SSL. When you see https:// (as oppos ed to just http://) in your browser,
you know that SSL is in the works and your communication with the
website is encrypted.
The increasing awareness to the confidentiality of our transactions (just
recall how much media noise was made following the releas e of
FireSheep) means that more companies are now deploying SSL. SSL is
not restricted anymore only to our banking services. Take, Google for
instance. At first, only the Gmail login page was encrypted. In time, the
whole Gmail service supported encryption – by default. Google has now
even added the search functionality to be accessed via https.
Threat #1: Attacks against PKI
It’s easy to see the powerful role that the CA has in the PKI model. Since,
at the base of this model is the underlying assumption th at the CA is
truthful, honest and legitimate. Consequently, a hacker who gains control
on a CA can then use it to issue fraudulent certificates and then
masquerade as any website.
Over the past year, attackers have repeatedly compromised various CA
organiz ations. These include, DigiNotar , GlobalSign , Comodo and
Digicert Malaysia. These attacks were a direct consequence of the
commoditization of certificates, where smaller, less competent
organizations have started to obtain a bigger s hare in the certificate
authority market. As it stands now, any CA can issue a digital certificate
for any application – without any required consent from application
owner.
Last weekend, Trustwave published a blog entry which in itself shows
how fragile i s this system. As a CA, they had once issued a certificate
specific to an unnamed private company which allowed the interception of
all SSL communications within the company. As part of this admission ,
Trustwave also announced that they will not repeat this type of offering
again.
Threat #2: The Theft of Issued Website Certificates
The problem here is that Web a pplication certificates are not simply
confined to being stored by the application. While SSL prevents access to
traffic by attackers, it has no built -in mechanisms that allow restrictive
access to it by collaborative third parties. For example, proxies, l oad
balancers, content delivery networks (CDNs) need to access the
certificate’s private key in order to access application data. Also data loss
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73 access. As a result, the digital certific ate is now stored in many locations -
some residing outside of the site's physical environment and out of the
application’s owner control. These open up additional attack points which
imply a higher success rate for attackers.
Threat #3: The Theft of Issue d Code Signing Certificates
The problem is not only with online services. Also applications present
certificates that attest to their legitimacy before performing sensitive
operations. Therefore, code signing certificates are too a prime target for
malware distributers. We’ve already witnessed this in the wild – Stuxnet
for instance used a stolen certificate. More recently, a malware strain used
a stolen certificate belonging to the Malaysian government.
Threat #4: Denial of Service attacks
Because of the e ncryption component – there is a heavy computational
burden incurred when initiating the SSL communication. Therefore, SSL -
protected resources are prime candidates for effective Denial of Service
(DoS) attacks. Together with an increased consumption of com puter
resources per session, a multitude of simple attacks can be devised very
efficiently.
4.7 SECURE ELECTRONIC TRANSACTION (SET)
Secure Electronic Transaction or SET is a system that ensures the
security and integrity of electronic transactions done usi ng credit cards in
a scenario. SET is not some system that enables payment but it is a
security protocol applied to those payments. It uses different encryption
and hashing techniques to secure payments over the internet done
through credit cards. The SET protocol was supported in development by
major organizations like Visa, Mastercard, Microsoft which provided its
Secure Transaction Technology (STT), and Netscape which provided the
technology of Secure Socket Layer (SSL).
SET protocol restricts the revea ling of credit card details to merchants
thus keeping hackers and thieves at bay. The SET protocol includes
Certification Authorities for making use of standard Digital Certificates
like X.509 Certificate.
Requirements in SET :
The SET protocol has some requirements to meet, some of the important
requirements are :
 It has to provide mutual authentication i.e., customer (or cardholder)
authentication by confirming if the customer is an intended user or
not, and merchant authentication.
 It has to keep the PI (Payment Information) and OI (Order
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74  It has to be resistive against message modifications i.e., no changes
should be allowed in the content being transmitted.
 SET also needs to provide interoperabili ty and make use of the best
security mechanisms.
Participants in SET :
In the general scenario of online transactions, SET includes similar
participants:
1. Cardholder – customer
2. Issuer – customer financial institution
3. Merchant
4. Acquirer – Merchant financia l
5. Certificate authority – Authority that follows certain standards and
issues certificates(like X.509V3) to all other participants.
SET functionalities :
 Provide Authentication
 Merchant Authentication – To prevent theft, SET allows customers
to check previ ous relationships between merchants and financial
institutions. Standard X.509V3 certificates are used for this
verification.
 Customer / Cardholder Authentication – SET checks if the use of
a credit card is done by an authorized user or not using X.509V3
certificates.
 Provide Message Confidentiality : Confidentiality refers to
preventing unintended people from reading the message being
transferred. SET implements confidentiality by using encryption
techniques. Traditionally DES is used for encryption purpose s.
 Provide Message Integrity : SET doesn’t allow message
modification with the help of signatures. Messages are protected
against unauthorized modification using RSA digital signatures with
SHA -1 and some using HMAC with SHA -1,
Dual Signature :
The dual si gnature is a concept introduced with SET, which aims at
connecting two information pieces meant for two different receivers :
Order Information (OI) for merchant Payment Information (PI) for
bank
You might think sending them separately is an easy and mor e secure
way, but sending them in a connected form resolves any future dispute
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75

Where,
PI stands for payment information
OI stands for order information
PIMD stands for Payment Information Message Dige st
OIMD stands for Order Information Message Digest
POMD stands for Payment Order Message Digest
H stands for Hashing
E stands for public key encryption
KPc is customer's private key
|| stands for append operation
Dual signature, DS= E(KPc, [H(H(PI)||H(OI ))])
Purchase Request Generation :
The process of purchase request generation requires three inputs:
 Payment Information (PI)
 Dual Signature
 Order Information Message Digest (OIMD)
The purchase request is generated as follows:

Here,
PI, OIMD, OI all h ave the same meanings as before.
The new things are :
EP which is symmetric key encryption
Ks is a temporary symmetric key
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76 CA is Cardholder or customer Certificate
Digital Envelope = E(KUbank, Ks)
Purchase Request Validation on Merchant Side :
The Merchant verifies by comparing POMD generated through PIMD
hashing with POMD generated through decryption of Dual Signature as
follows:


Since we used Customer’s private key in encryption here we use KUC
which is the public key of t he customer or cardholder for decryption
‘D’.


Payment Authorization and Payment Capture : Payment
authorization as the name suggests is the authorization of payment
information by the merchant which ensures payment will be received by
the merchant. Pa yment capture is the process by which a merchant
receives payment which includes again generating some request blocks
to gateway and payment gateway in turn issues payment to the merchant.
4.8 KERBEROS[5]
Kerberos provides a centralized authentication serv er whose function is
to authenticate users to servers and servers to users. In Kerberos
Authentication server and database is used for client authentication.
Kerberos runs as a third -party trusted server known as the Key
Distribution Center (KDC). Each use r and service on the network is a
principal.
The main components of Kerberos are:
 Authentication Server (AS):
The Authentication Server performs the initial authentication and
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77  Database:
The Authentication Server ver ifies the access rights of users in the
database.
 Ticket Granting Server (TGS):
The Ticket Granting Server issues the ticket for the Server

Kerberos Overview:


 Step -1:
User login and request services on the host. Thus user requests for
ticket -granting service.
 Step -2:
Authentication Server verifies user’s access right using database and
then gives ticket -granting -ticket and session key. Results are
encrypted using the Password of the user.
 Step -3:
The decryption of the message is done using the password then send
the ticket to Ticket Granting Server. The Ticket contains
authenticators like user names and network addresses.
 Step -4:
Ticket Granting Server decrypts the ticket sent by User and
authenticator verifies the request then creates t he ticket for requesting
services from the Server.
 Step -5:
The user sends the Ticket and Authenticator to the Server.
 Step -6:
The server verifies the Ticket and authenticators then generate access
to the service. After this User can access the servic es. munotes.in

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78 Kerberos Limitations
 Each network service must be modified individually for use with
Kerberos
 It doesn’t work well in a timeshare environment
 Secured Kerberos Server
 Requires an always -on Kerberos server
 Stores all passwords are encrypted with a sing le key
 Assumes workstations are secure
 May result in cascading loss of trust.
 Scalability
4.9 SUMMARY
Protection of this accessible information assets from a Web Server is
known as Server Security. A security break can destructively affect the
goodwill as well as the economic status of an organization. Web server
security becomes highly important when it is connected to the internet.
4.10 REFERENCES FOR READING
1. Examining Threats Facing Public Key Infrastructu
https://www.securityweek.com/examining -threa ts-facing -public -key-
infrastructure -pki-and-secure -socket -layer -sslre (PKI) and Secure
Socket Layer (SSL) | SecurityWeek.Com

2. https://www.geeksforgeeks.org/secure -socket -layer -ssl/

3. https://www.geeksforgeeks.org/secure -electronic -transaction -set-
protocol/?ref=lbp

4. https://www.geeksforgeeks.or g/kerberos/






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79 5
CLOUD SECURITY
Unit Structure:
5.0 Objective
5.1 Introduction
5.2 How concepts of Security apply in the cloud
5.2.1 User authentication in the cloud
5.2.2 Techniques used in user Authentication
5.2.3 Algorithms For User Authentication
5.2.4 Protocols Used In The Process of User Authentication And
Authorization
5.3 Virtualization System
5.3.1 Virtualization System Security Issues
5.3.2 ESX and ESXi Security
5.3.3 ESX file system security - storage considerations, backup and
recovery
5.3.4 Virtualiz ation System Vulnerabilities
5.4 Security management standards
5.4.1 SaaS
5.4.2. PaaS
5.4.3. IaaS
5.5 Availability Management
5.6 Access control
5.6.1Access Control Models
5.7 Data security and storage in cloud
5.8 Summary
5.9 Questions
5.10 Refere nce for further reading
5.0 OBJECTIVE
Three key cyber security objectives: ensuring confidentiality, integrity and
availability of information resources and systems are high -priority
concerns and potential risks to cloud technology. The implementation of
cloud technology is subject to local physical threats as well as remote,
external threats. Consistent with other IT applications, threat sources
include accidents, natural disasters, and external loss of service, hostile
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80 unintentional vulnerabilities through internal/external authorized and
unauthorized system access, including but not limited to employees,
contractors, vendors and intruders. The characteristics of cloud
technology, speci fically multi -tenancy and implications of three service
and four deployment models, heighten the efforts to protect Postal Service
data and systems, as well as physical boundaries.
5.1 INTRODUCTION
Cybersecurity is the protection of computer systems and networks from
information disclosure, theft of or damage to their hardware , software ,
or electronic data , as well a s from the disruption or misdirection of the
services they provide.
The field is becoming incr easingly significant due to the increased reliance
on computer systems , the Internet and wireless network standards such
as Bluetooth and Wi-Fi, and d ue to the growth of "smart" devices ,
including smartphones , televisions , and the various devices that constitute
the " Internet of things ". Owing to its complexity, both in terms of politics
and technology, cybersecurity is also one of the major challenges in the
contemporary world.
5.2 HOW CONCEPTS OF SECURITY APPLY IN THE
CLOUD?
5.2.1 User authentication in the cloud
Cloud computing provides customers with highly scalable and on -mend
computing resources. N IST specified three cloud service models:
Software as a Service (SaaS), Platform as a Service (PaaS), Infrastructural
as a Service (IaaS), each service models target a specific need of
customers.
 Software as a Service offers applications that were provid ed by the
cloud service providers and hosted by the cloud provider.
 Platform as a Service offers hosting environment for developers to
develop and publish their applications.
 Infrastructural as a Service offers visualised computing resources such
as virt ual desktop, virtual storage, etc. Various cloud services and
cloud service providers are beneficial for customers who seek specific
computing resource, it creates some security challenges to the
customers seeking different cloud services however.
1. Cloud s ervice providers request customers to store their account
information in the cloud and they have the access to this information.
This presents a privacy issue to the customer’s privacy information.
2. Many SLAs have specified the privacy of the sensitive inf ormation. It
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81 There is a lack of transparency in the cloud that allows the customers
to monitor their own privacy information.
3. When a customer decides to use multiple cloud service, the customer
will have to store the password in multiple cloud. As the user takes
cloud subscription of any cloud service that much number of copies of
the users information are created. This is a security issue for the
customers and the cloud service provide rs.
4. The multiple copies of account will lead to multiple authentication
processes. For every cloud service, the customer needs to exchange
their authentication information.
5. Cloud service providers use different authentication technologies for
authenticat ing users, this may have less impact on SaaS than PaaS and
IaaS, but it is present a challenge to the customers. The key concept to
user authentication is that a user who established an identity by
connection with cloud computing can use the same identity with other
clouds also.
6. As users communicate with the Cloud, identity becomes an important
issue to maintain security, visibility and control. In this distributed
environment, it is essential for applications to authenticate the user’s
identity, understan d what that user is authorized to do, create or update
an account and audit their activities. Thus authentication and
authorization are critical components of a cloud identity strategy and
provide portability and extensibility beyond enterprise boundaries.
Authentication
Authentication is the process for confirming the identity of the user. The
traditional authentication process allows the system to identify the user
through a username and then validate their identity through password.
There are even stron ger methods of user authentication such as x.509
certificates, one -time passwords (OTP), and device fingerprinting. These
can be combined to provide a stronger combination of authentication
factors. Federated identity allows a user to access an application in one
domain, such as a Software -as-asService (SaaS) application, using the
authentication that occurred in another domain, such as a corporate
Identity Management (IdM) system.
5.2.2 Techniques used in user Authentication
Identity and Access Control Se rvice should provide identity management
and access control to cloud resources for registered entities. Such entities
can be people, software processes or other systems. In order to give a
proper level of access to a resource, the identity of an entity sho uld be
verified first, which is the authentication process that precedes the
authorization process. Besides authentication and authorization processes,
audit logging mechanism should be used to keep track of all successful
and failed operations regarding a uthentication and access attempts by the
application. Confidentiality is achieved by different encryption munotes.in

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82 mechanisms, which is the procedure of encoding data by means of
cryptographic algorithms. Providing such a service will guarantee privacy
of sensitive and private data and the intended entity can only decode it.
Cryptographic algorithms, which are computationally hard to crack
together with encryption and decryption procedures, digital signatures,
hashing, certificates, key exchange and management form an encryption
system which can be delivered as a service and assure confidentiality and
non-repudiation in a cloud environment.

5.2.3 Algorithms For User Authentication
The central idea behind the Security provision is to avoid the unwanted
intrusion of unauthorized users and right at the entry point. That is all the
users whether new of existing are not allowed to access the data or
resources without proving their identity. The request from the users are
first encrypted and then sent to the cloud files. The algorithms used to
encryption process are discussed as follows:
1. RSA Algorithm : RSA encryption algorithm is used for making the
communication safe. Usually the users' requests are encrypted while
sending to the cloud service provider system. RSA algor ithm using the
system's public key is used for the encryption. Whenever the user
requests for a file the system sends it by encrypting it via RSA
encryption algorithm using the user’s public key. Same process is also
applied about the user password request s, while logging in the system
later. After receiving an encrypted file from the system the user’s
browser will decrypt it with RSA algorithm using the user’s private
key. Similarly when the system receives an encrypted file from the
user it will immediate ly decrypt it using its private key. As a result the
communication becomes secured between the user and the system.
2. AES Algorithm & MD5 Hashing Algorithm : When a file is
uploaded by an user the system server encrypts the file using AES
encryption algorithm . In this 128, 192, 256 bit key can be used. The
key is generated randomly by the system server. A single key is used
only once. That particular key is used for encrypting and decrypting a
file of a user for that instance. This key is not further used in a ny
instance later. The key is kept in the database table of the system
server along with the user account name. Before inserting the user
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83 unauthorized person cannot retrieve the key to dec rypt a particular file
for a particular user by simply gaining access and observing the
database table of the system server. As a result the key for a particular
file becomes hidden and safe. Again when the encrypted file is
uploaded for storing to the sto rage server, the path of the encrypted file
along with the user account is kept and maintained in the database
table on the storage server. Here user name is used for synchronization
between the database tables of main system server and the storage
server. The encrypted files on the storage server are inserted not
serially.
3. OTP Password Algorithm : In this algorithm one time password has
been used for authenticating the user. The password is used to keep the
user account secure and secret from the unauthoriz ed user. But the user
defined password can be compromised. To overcome this difficulty
one time password is used in the proposed security model. Thus
whenever a user logs in the system, he will be provided with a new
password for using it in the next login . This is usually provided by the
system itself. This password will be generated randomly. Each time a
new password is created for a user, the previous password for that user
will be erased from the system. New password will be updated for that
particular user. A single password will be used for login only once.
The password will be sent to the users authorized mail account.
Therefore at a same time a check to determine the validity of the user
is also performed. As a result only authorized user with a vali d mail
account will be able to connect to the cloud system.
4. Data Encryption Standard Algorithm : Data Encryption Standard
algorithm is a type of symmetric -key encipherment algorithms.
Symmetric -key encryption is a type of cryptosystem in which
encryption an d decryption are performed using a single (secret) key.
As we can see, secret key play a very important role in DES security,
so that a good key generation unit required. Using Dynamic key
generator, the generated key has characteristics of unpredictabilit y and
unrepeatability. Using this approach the dynamic key generator can
achieve the high speed and can be reduce logic complexity.
5. Rijndael encryption Algorithm : Rijndael is the standard symmetric
key encryption algorithm to be used to encrypt sensitive information.
Rijndael is an iterated block cipher, the encryption or decryption of a
block of data is accomplished by the iteration (a round) of a specific
transformation (a round function). As input, Rijndael accepts one -
dimensional 8 -bit byte arrays that create data blocks. The plaintext is
input and then mapped onto state bytes. The cipher key is also a one -
dimensional 8 -bit byte array. With an iterated block cipher, the
different transformations operate in sequence on intermediate cipher
results (states ).

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84 5.2.4 Protocols Used In The Process of User Authentication
Identity and Access Control Service should provide identity management
and access control to cloud resources for registered entities. Such entities
can be people, software processes or other systems. In order to give a
proper level of access to a resource, the identity of an entity should be
verified first, which is the authentication process that precedes the
authorization process. Besides authentication and authorization processes,
audit log ging mechanism should be used to keep track of all successful
and failed operations regarding authentication and access attempts by the
application. Confidentiality is achieved by different encryption
mechanisms, which is the procedure of encoding data by means of
cryptographic algorithms. Providing such a service will guarantee privacy
of sensitive and private data and the intended entity can only decode it.
Cryptographic algorithms, which are computationally hard to crack
together with encryption and decr yption procedures, digital signatures,
hashing, certificates, key exchange and management form anencryption
system which can be delivered as a service and assure confidentiality and
non-repudiation in a cloud environment.
Authentication Protocols used are as follows:
1. Extensible Authentication Protocol -CHAP : EAP(Extensible
Authentication Protocol) will implement on Cloud environment for
authentication purpose. It is used for the transport and usage of keying
material and parameters generated by EAP methods . In our purposed
model we use Challenge -Handshake Authentication Protocol (CHAP)
for authentication.
2. Lightweight Directory Access Protocol : Most companies are storing
their important information in some type of Lightweight Directory
Access Protocol server . SaaS providers can provide delegate the
authentication process to the customer’s internal LDAP/AD server, so
that companies can retain control over the management of users.
3. Single Sign -on (SSO) protocol : This protocol is part of the shared
security syst em of a cloud environment. The system consists of a
SAML server which provides SSO services for application service
providers: SAML server issues SAML ticket which contains an
assertion about the client’s identity verification, thus confirming that it
has been properly authenticated or not. Once the user is authenticated,
he or she can request access to different authorized resources at
different application provider sites without the need to reauthenticate
for each domain.
5.3 VIRTUALIZATION SYSTEM
Virtu alization is the "creation of a virtual (rather than actual) version of
something, such as a server, a desktop, a storage device, an operating
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85 In other words, Virtualization is a technique, which allows to share a
single physi cal instance of a resource or an application among multiple
customers and organizations. It does by assigning a logical name to a
physical storage and providing a pointer to that physical resource when
demanded.
Virtualization plays a very important role i n the cloud computing
technology, normally in the cloud computing, users share the data present
in the clouds like application etc, but actually with the help of
virtualization users shares the Infrastructure.
The main usage of Virtualization Technology is to provide the
applications with the standard versions to their cloud users, suppose if the
next version of that application is released, then cloud provider has to
provide the latest version to their cloud users and practically it is possible
because it is more expensive.
To overcome this problem we use basically virtualization technology, By
using virtualization, all severs and the software application which are
required by other cloud providers are maintained by the third party people,
and the cloud pro viders has to pay the money on monthly or annual basis.

Creation of a virtual machine over existing operating system and hardware
is known as Hardware Virtualization. A Virtual machine provides an
environment that is logically separated from the underlyi ng hardware.
The machine on which the virtual machine is going to create is known
as Host Machine and that virtual machine is referred as a Guest Machine
5.3.1 Virtualization System Security Issues
Bad storage, server, and network configurations are just a few reasons
why virtualization fails. These are technical in nature and are often easy to
fix, but some organizations overlook the need to protect their entire
virtualized environments, thinking that they’re inherently more secure
than traditional IT env ironments. Others use the same tools they use to
protect their existing physical infrastructure. The bottom line is that a
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86 approach. These are the common problems talked about behind clo sed
doors.
1.Resource distribution
The way virtualization partitions systems can result in varied ways —
some might function really well, and others might not provide users access
to enough resources to meet their needs. Resource distribution problems
often occur in the shift to virtualization and can be fixed by working on
capacity planning with your service provider.
2. VM Sprawl
VM sprawl, the unchecked growth of virtual machines in a virtual
environment, as any virtualization admin knows, can cripple an otherwise
healthy environment. It is problematic because its underlying cause often
stays hidden until it manifests in resource shortages.
You should look at how virtual machines will be managed, who will be
doing what, and what systems you’re going to us e. One of the optimal
times to develop an overall management plan is when you’re in a testing
phase, before migration.
3.Backward compatibility
Using legacy systems can cause problems with newer virtualized software
programs. Compatibility issues can be ti me-consuming and difficult to
solve. A good provider may be able to suggest upgrades and workarounds
to ensure that everything functions the way they should.
4. Performance monitoring
Virtualized systems don’t lend themselves to the same kind of
performanc e monitoring as hardware like mainframes and hardware drives
do. Try tools like VMmark to create benchmarks that measure
performance on virtual networks and to monitor resource usage as well.
5.Backup
In a virtualized environment, there is no actual hard d rive on which data
and systems can be backed up. This means frequent software updates can
make it difficult to access backup at times. Software programs like
Windows Server Backup tools can make this process easier and allow
backups to be stored in one pla ce for easier tracking and access.
5.Security
Virtual systems could be vulnerable when users don’t keep them secure
and apply best practices for passwords or downloads. Security then
becomes a problem for virtualization, but the isolation of each VM by the
system can mitigate security risks and prevent systems from getting
breached or compromised.
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87 5.3.2 ESX and ESXi Security
According to the latest statistics, VMware holds more than 75% of the
global server virtualization market, which makes the company t he
undisputed leader in the field, with its competitors lagging far behind.
VMware hypervisor provides you with a way to virtualize even the most
resource -intensive applications while still staying within your budget. If
you are just getting started with V Mware software, you may have come
across the seemingly unending ESX vs. ESXi discussion. These are two
types of VMware hypervisor architecture, designed for “bare -metal”
installation, which is directly on top of the physical server (without
running an oper ating system
What Does ESXi Stand for and How Did It All Begin?
If you are already somewhat familiar with the VMware product line, you
may have heard that ESXi, unlike ESX, is available free of cost. This has
led to the common misconception that ESX server s provide a more
efficient and feature -rich solution, compared to ESXi servers. This notion,
however, is not entirely accurate.
ESX is the predecessor of ESXi. The last VMware release to include both
ESX and ESXi hypervisor architectures is vSphere 4.1 (“v Sphere”). Upon
its release in August 2010, ESXi became the replacement for ESX.
VMware announced the transition away from ESX, its classic hypervisor
architecture, to ESXi, a more lightweight solution.
The primary difference between ESX and ESXi is that ES X is based on a
Linux -based console OS, while ESXi offers a menu for server
configuration and operates independently from any general -purpose OS.
For your reference, the name ESX is an abbreviation of Elastic Sky X,
while the newly -added letter “i” in ESXi stands for “integrated.” As an
aside, you may be interested to know that at the early development stage
in 2004, ESXi was internally known as “VMvisor” (“VMware
Hypervisor”), and became “ESXi” only three years later. Since version 5,
released in July 2011 , only ESXi has continued.
ESX vs. ESXi: Key Differences
Overall, the functionality of ESX and ESXi hypervisors is effectively the
same. The key difference lies in architecture and operations management.
If only to shorten the VMware version comparison to a few words, ESXi
architecture is superior in terms of security, reliability, and management.
Additionally, as mentioned above, ESXi is not dependent on an operating
system. VMware strongly recommends their users currently running the
classic ESX architect ure to migrate to ESXi. According to VMware
documentation, this migration is required for users to upgrade beyond the
4.1 version and maximize the benefits from their hypervisor.
To protect an ESXi host against an unauthorized intrusion and misuse,
VMware imposes constraints on several parameters, settings, and
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88 needs. If you do, make sure that you are working in a trusted environment
and take other security measures.
Built -In Security Fea tures
Risks to the hosts are mitigated as follows:
 ESXi Shell and SSH interfaces are disabled by default. Keep these
interfaces disabled unless you are performing troubleshooting or
support activities. For day -to-day activities, use the vSphere Client ,
where activity is subject to role -based access control and modern
access control methods.
 Only a limited number of firewall ports are open by default. You can
explicitly open additional firewall ports that are associated with
specific services.
 ESXi runs only services that are essential to managing its functions.
The distribution is limited to the features required to run ESXi .
 By default, all ports that are not required for management access to the
host are closed. Open ports if you need additional services.
 By default, weak ciphers are disabled and communications from
clients are secured by SSL. The exact algorithms used for securing the
channel depend on the SSL handshake. Default certificates created
on ESXi use PKCS#1 SHA -256 with RSA encryption as the sig nature
algorithm.
 An internal web service is used by ESXi to support access by Web
clients. The service has been modified to run only functions that a
Web client requires for administration and monitoring. As a
result, ESXi is not vulnerable to web service security issues reported in
broader use.
 VMware monitors all security alerts that can affect ESXi security and
issues a security patch if needed. You can subscribe to the VMware
Security Advisories and Security Alerts mailing list to receive security
alerts
 Insecure services such as FTP and Telnet are not installed, and the
ports for these services are closed by default.
 To protect hosts from loading drivers and applications that are not
cryptographically signed, use UEFI Secure boot. Enabling Secure Boot
is done at the system BIOS. No additional configuration changes are
required on the ESXi host, for example, to disk partitions.
 If your ESXi host has a TPM 2.0 chip, enable and configure the chip in
the system BIOS. Working together with Secure Boot, TPM 2.0
provides enhanced security and trust assurance rooted in hardware.
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89 Additional Security Measures
Consider the following recommendations when evaluating host security
and administration.
Limit access
If you enable access to the Direct Console User Inte rface (DCUI),
the ESXi Shell , or SSH, enforce strict access security policies.
The ESXi Shell has privileged access to certain parts of the host. Provide
only trusted users with ESXi Shell login access.
Do not access managed hosts directly
Use the vSphere Client to administer ESXi hosts that are managed by
a vCenter Server . Do not access managed hosts directly with the VMware
Host Client , and do not change managed hosts from the DCUI.
If you manage hosts with a scripting interface or API, do not target the
host directly. Instead, target the vCenter Server system that manages the
host and specify the host name.
Use DCUI only for troubleshooting
Access the host from the DCUI or the ESXi Shell as the root user only for
troubleshooting. To administer your ESXi hosts, use one of the GUI
clients, or one of the VMware CLIs or APIs. See ESXCLI Concepts and
Use only VMware sources to upgrade ESXi components
The host runs several third -party packages to support management
interfaces or tasks that you must perform. VMw are only supports upgrades
to these packages that come from a VMware source. If you use a
download or patch from another source, you might compromise
management interface security or functions. Check third -party vendor sites
and the VMware knowledge base f or security alerts.
5.3.3 ESX file system security - storage considerations, backup and
recovery
VMware developed its own high performance cluster file system called
VMware Virtual Machine File System or VMFS. VMFS provides a file
system which has been opt imized for storage virtualization for virtual
machines through the use of distributed locking. A virtual machine stored
on a VMFS partition always appears to the virtual machine as a mounted
SCSI disk. The virtual disk or *.vmdk file hides the physical sto rage layer
from the virtual machine's operating system. VMFS versions 1 and 2 were
flat file systems, and typically only housed .vmdk files. The VMFS 3 file
system now allows for a directory structure. As a result, VMFS 3 file
systems can contain all of th e configuration and disk files for a given
virtual machine. The VMFS file system is one of the things that set
VMware so far ahead of its competitors. Conventional file systems will
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90 given time. VMware's VMFS is a file system which will allow multiple
nodes or multiple VMware ESX servers to read and write to the same
LUN or VMFS partition concurrently.
Now that we know about VMFS, let's take a look at the different storage
options t hat are made available.
Direct -attached storage
Direct -attached storage (DAS) is storage that is, as the name implies,
directly attached to a computer or server. DAS is usually the first step
taken when working with storage. A good example would be a compa ny
with two VMware ESX Servers directly attached to a disk array. This
configuration is a good starting point, but it typically doesn't scale very
well.
Network -attached storage
Network -attached storage (NAS) is a type of storage that is shared over
the ne twork at a file system level. This option is considered an entry -level
or low -cost option with a moderate performance rating. VMware ESX will
connect over the network to a specialized storage device. This device can
be in the form of an appliance or a comp uter that uses Network File
System (NFS).
The VMkernel is used to connect to a NAS device via the VMkernel port
and supports NFS Version 3 carried over TCP/IP only. From the
standpoint of the VMware ESX servers, the NFS volumes are treated the
same way VMw are ESX would treat iSCSI or Fibre Channel storage. You
are able to VMotion guests from one host to the next, create virtual
machines, boot virtual machines as well as mount ISO images as CD -
ROMs when presented to the virtual machines.
When configuring acc ess to standard Unix/Linux -based NFS devices,
some configuration changes will need to be defined. The directory
/etc/exports will define the systems that are allowed to access the shared
directory. And there are a few options in this file that you should b e aware
of.
1. Name the directory to be shared.
2. Define the subnets that will be allowed access to the share.
3. Allow both "read" and "write" permissions to the volume.
4. no_root_squash -- The root user (UID = 0) by default is given the least
amount of access to the volume. This option will turn off this behavior,
giving the VMkernel the access it needs to connect as UID 0.
5. sync -- All file writes MUST be committed to the disk before the client
write request is actually completed.
Windows Server 2003 R2 also natively provides NFS sharing when the
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91 of the box, Windows Server 2003 R2 has this ability, but it can also be run
on Windows Server 2003 (non -R2), and Windows 2000 Server af ter
downloading SFU from Microsoft's Website.
1. After storage has been allocated, the folders are presented similarly as
NFS targets.
2. Because there is no common authentication method between VMware
ESX and a Microsoft Windows server, the /etc/passwd file mus t be
copied to the Windows server, and mappings must be made to tie an
account on the ESX server to a Windows account with appropriate
access rights.
5.3.4 Virtualization System Vulnerabilities
Virtualization has eased many aspects of IT management but ha s also
complicated the task of cyber security.The nature of virtualization
introduces a new threat matrix, and administrators need to address the
resulting vulnerabilities in their enterprise environments.
Critical Virtualization Vulnerabilities
Some attac ks against virtual machine, or VM, environments are variations
of common threats such as denial of service. Others are still largely
theoretical but likely approaching as buzz and means increase. Keep an
eye on these critical weaknesses:
1. VM sprawl: VMs are easy to deploy, and many organizations view
them as hardware -like tools that don’t merit formal policies.This has
led to VM sprawl, which is the unplanned proliferation of
VMs.Attackers can take advantage of poorly monitored
resources.More deployments als o mean more failure points, so sprawl
can cause problems even if no malice is involved.

2. Hyperjacking: Hyperjacking takes control of the hypervisor to gain
access to the VMs and their data. It is typically launched against type 2
hypervisors that run over a host OS although type 1 attacks are
theoretically possible. In reality, hyperjackings are rare due to the
difficulty of directly accessing hypervisors.However, hyperjacking is
considered a real -world threat, and administrators should take the
offensive a nd plan for it.

3. VM escape: A guest OS escapes from its VM encapsulation to interact
directly with the hypervisor.This gives the attacker access to all VMs
and, if guest privileges are high enough, the host machine as well.
Although few if any instances ar e known, experts consider VM escape
to be the most serious threat to VM security.

4. Denial of service: These attacks exploit many hypervisor platforms
and range from flooding a network with traffic to sophisticated
leveraging of a host’s own resources.The a vailability of botnets
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92 specific servers and applications with the goal of derailing the target’s
online services.

5. Incorrect VM isolation: To remain secure and correctly share
resourc es,VMs must be isolated from each other.Poor control over VM
deployments can lead to isolation breaches in which VMs
communicate.Attackers can exploit this virtual drawbridge to gain
access to multiple guests and possibly the host.

6. Unsecured VM migration: This occurs when a VM is migrated to a
new host, and security policies and configuration are not updated to
reflect the change.Potentially, the host and other guests could become
more vulnerable.Attackers have an advantage in that administrators are
likely unaware of having introduced weaknesses and will not be on
alert.

7. Host and guest vulnerabilities: Host and guest interactions can
magnify system vulnerabilities at several points.Their operating
systems, particularly Windows, are likely to have multiple
weaknesses.Like other systems, they are subject to vulnerabilities in
email, Web browsing, and network protocols.However, virtual
linkages and the co -hosting of different data sets make a serious attack
on a virtual environment particularly damaging.
How to Mitigate Risk
Fortunately, security engineers can take several steps to minimize risk.The
first task is to accurately characterize all deployed virtualization and any
active security measures beyond built -in hypervisor controls on
VMs.Security controls should be compared against industry standards to
determine gaps.Coverage should include anti -virus, intrusion detection,
and active vulnerability scanning.Additionally, consider these action steps:
VM traffic monitoring:The ability to monitor VM backbone network
traffic is critical.Conventional methods will not detect VM traffic because
it is controlled by internal soft switches.However, hypervisors have
effective monitoring tools that should be enabled and tested.
Administrative control:Secure access can become compromised due to
VM sprawl and other issues.
o Ensure that authentication procedures, identity management, and
logging are ironclad.

o Customer security:Outside of the VM, make sure protection is in place
for customer -facing interfaces such as websit es.

o VM segregation:In addition to normal isolation, strengthen VM
security through functional segregation.For example, consider creating
separate security zones for desktops and servers.The goal is to
minimize intersection points to the extent feasible.
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93
5.4 SECURITY MANAGEMENT STANDARDS
5.4.1. SaaS
Software -as-a-Service (SaaS) is a software licensing model in which
access to the software is provided on a subscription basis, with the
software being located on external servers rather than on servers loca ted
in-house.
Software -as-a-Service is typically accessed through a web browser, with
users logging into the system using a username and password. Instead of
each user having to install the software on their computer, the user is able
to access the program via the Internet.
 Software -as-a-Service (SaaS) is a software licensing model, which
allows access to software a subscription basis using external servers.
 SaaS allows each user to access programs via the Internet, instead of
having to install the software on the user's computer.
 SaaS has many business applications, including file sharing, email,
calendars, customer retention management, and human resources.
 SaaS is easy to implement, easy to update and debug, and can be less
expensive (or at least have low er up -front costs) since users pay for
SaaS as they go instead of purchasing multiple software licenses for
multiple computers.
 Drawbacks to the adoption of SaaS center around data security, speed
of delivery, and lack of control.
Understanding Software -as-a-Service (SaaS)
The rise of Software -as-a-Service (SaaS) coincides with the rise of cloud -
based computing . Cloud computing is the process of offering technology
services through the I nternet, which often includes data storage,
networking, and servers. Before SaaS was available, companies looking to
update the software on their computers had to purchase compact disks
containing the updates and download them onto their systems.
For large organizations, updating software was a time -consuming
endeavor. Over time, software updates became available for download
through the Internet, with companies purchasing additional licenses rather
than additional disks. However, a copy of the software sti ll needed to be
installed on all devices that needed access to it.
What Is Software -as-a-Service (SaaS)?
Software -as-a-Service (SaaS) is a software licensing model in which
access to the software is provided on a subscription basis, with the
software being located on external servers rather than on servers located
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94 Software -as-a-Service is typically accessed through a web browser, with
users logging into the system using a username and password. Instead of
each user having to install the software o n their computer, the user is able
to access the program via the Internet.
KEY TAKEAWAYS
 Software -as-a-Service (SaaS) is a software licensing model, which
allows access to software a subscription basis using external servers.
 SaaS allows each user to acces s programs via the Internet, instead of
having to install the software on the user's computer.
 SaaS has many business applications, including file sharing, email,
calendars, customer retention management, and human resources.
 SaaS is easy to implement, eas y to update and debug, and can be less
expensive (or at least have lower up -front costs) since users pay for
SaaS as they go instead of purchasing multiple software licenses for
multiple computers.
 Drawbacks to the adoption of SaaS center around data secur ity, speed
of delivery, and lack of control.
Understanding Software -as-a-Service (SaaS)
The rise of Software -as-a-Service (SaaS) coincides with the rise of cloud -
based computing . Cloud computing is the process of offering technology
services through the Internet, which often includes data storage,
networking, and servers. Before SaaS was available, companies looking to
update the software on their computers had to purchase compact disks
containing the updates and download them onto their systems.
For large organizations, updating software was a time -consuming
endeavor. Over time, software updates became available for download
through the Internet, with companies purchasing additional lice nses rather
than additional disks. However, a copy of the software still needed to be
installed on all devices that needed access to it.
With SaaS, users don’t need to install or update any software. Instead,
users can log in through the Internet or web br owser and connect to the
service provider’s network to access the particular service.
Advantages and Disadvantages of SaaS
Advantages
SaaS offers a variety of advantages over traditional software licensing
models. Because the software does not live on the licensing company’s
servers, there is less demand for the company to invest in new hardware.
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95 as they go instead of purchasing multiple software licenses for multiple
computers.
SaaS has numerous applications, including:
 Email services
 Auditing functions
 Automating sign -up for products and services
 Managing documents, including file sharing and document
collaboration
 Shared company calendars, which can be used for scheduling events
 Customer relationship management (CRM) systems, which are
essentially a database of client and prospect inf ormation. SaaS -based
CRMs can be used to hold company contact information, business
activity, products purchased as well as track leads.
Types of software that have migrated to a SaaS model are often focused
on enterprise -level services, such as human reso urces. These types of tasks
are often collaborative in nature, requiring employees from various
departments to share, edit, and publish material while not necessarily in
the same office.
Disadvantages
Drawbacks to the adoption of SaaS centeraround data sec urity and speed
of delivery. Because data is stored on external servers, companies have to
be sure that it is safe and cannot be accessed by unauthorized parties.
Slow Internet connections can reduce performance, especially if the cloud
servers are being a ccessed from far -off distances. Internal networks tend
to be faster than Internet connections. Due to its remote nature, SaaS
solutions also suffer from a loss of control and a lack of customization.
Examples of SaaS
Google Docs
One of the simplest real -world examples of SaaS is Google Docs,
Google's free online word processor.
In order to use Google Docs, all you need to do is log in on a web browser
for instant access. Google Docs allows you to write, edit, and even
collaborate with others wherever you ha ppen to be.
Google Docs was launched in October 2012.
Dropbox
Dropbox is another simple example of SaaS in real life. Dropbox is a
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96 files and data. For example, users are able to ba ck up and sync photos,
videos, and other files to the cloud and access them from any device, no
matter where they are.
Dropbox was founded in 2007.
5.4.2 PaaS
PaaS, or Platform -as-a-Service, is a cloud computing model that provides
customers a complete cloud platform —hardware, software, and
infrastructure —for developing, running, and managing applications
without the cost, complexity, and inflexibility that often comes with
building and maintaining that platform on-premises.
The PaaS provider hosts everything —servers, networks, storage, operating
system software, databases, development tools —at their data center.
Typically customers can pay a fixed fee to provide a specified amount of
resources for a specified number of users, or they can choose 'pay -as-you-
go' pricing to pay only for the resources they use. Either option
enables PaaS customers to build, test, deploy run, update and scale
applications more quickly a nd inexpensively they could if they had to
build out and manage their own on-premises platform.
Every leading cloud service provider —including Amazon Web
Services (AWS), Google Cloud, IBM Cloud and Microsoft Azure —has its
own PaaS offering. Popular PaaS so lutions are also available as open
source projects (e.g. Apache Stratos, Cloud Foundry) or from software
ventors (e.g. Red Hat OpenShift and Salesforce Heroku).
Benefits of PaaS
The most commonly -cited benefits of PaaS, compared to an on -
premises platform, include:
 Faster time to market. With PaaS, there’s no need to purchase and
install the hardware and software you use to build and maintain your
application development platform —and no need for development
teams to wait while you do this. You simply tap in to the cloud
service provider’s PaaS to begin provisioning resources and
developing immediately.
 Affordable access to a wider variety of resources. PaaS platforms
typically offer access to a wider range of choices up and down the
application stack — includi ng operating systems, middleware ,
databases and development tools —than most organizations can
practically or affordably maintain themselves.
 More freedom to experiment, with less risk. PaaS also lets you try
or test new operating systems, languages and other tools without
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97  Easy, cost-effective scalability. With an on-premises platform,
scaling is always expensive, often wasteful and sometimes
inadequate: You have to purchase additional compute, storage and
networking capacity in anticipation of traffic spikes; much of that
capacity sits idle during low -traffic periods, and none of it can be
increased in time to accommodate unanticipated surges. With PaaS,
you can purchase additional capacity, and start using it immediately,
whenever you need it.
 Greater flexibility for development teams. PaaS services provide a
shared software devel opment environment that allows development
and operations teams access to all the tools they need, from any
location with an internet connection.
 Lower costs overall. Clearly PaaS reduces costs by enabling an
organization to avoid capital equipment expense associated with
building and scaling an application platform. But PaaS also can also
reduce or eliminate software licensing costs. And by handling
patches, updates and other administrative tasks, PaaS can reduce your
overall application management costs.
How PaaS works
In general, PaaS solutions have three main parts:
 Cloud infrastructure including virtual machines (VMs) , operating
system software, storage, ne tworking, firewalls
 Software for building, deploying and managing applications
 A graphic user interface, or GUI, where development or DevOps
team s can do all their work throughout the entire application
lifecycle
Because PaaS delivers all standard development tools through the GUI
online interface, developers can log in from anywhere to collaborate on
projects, test new applications, or roll out co mpleted products.
Applications are designed and developed right in the PaaS using
middleware. With streamlined workflows, multiple development and
operations teams can work on the same project simultaneously.
PaaS providers manage the bulk of your cloud co mputing services, such as
servers, runtime and virtualization. As a PaaS customer, your company
maintains management of applications and data.
Use cases for PaaS
By providing an integrated and ready -to-use platform —and by enabling
organizations to offload infrastructure management to the cloud
provider and focus on building, deploying and managing applications —
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98  API development and management : Because of its built -in
frameworks, PaaS makes it muc h simpler for teams to develop, run,
manage and secure APIs (application programming interfaces) for
sharing data and functionality between applications.
 Internet of Things (IoT) : Out of the box, PaaS can support a range
of programming languages (Java, Python, Swift, etc.), tools and
application environments used for IoT application development and
real-time processing of data generated by IoT devices.
 Agile development and DevOps: PaaS can provide fully -configured
environments for automating the software application lifecycle
including integration, delivery, security, testing and deployment.
 Cloud migration and cloud -native development: With its ready -to-
use tools and integration c apabilities, PaaS can simplify migration of
existing applications to the cloud —particularly via replatforming
(moving an application to the cloud with modifications that take
better advantage of cloud scalability, load balancing and other
capabilities) or refactoring (re-architectin g some or all of an
application using microservices , containers and other cloud -native
technologies).
 Hybrid cloud strategy: Hybrid cloud integrates public cloud
services, private cloud services and on-premises infrastructure and
provides orch estration, management and application portability
across all three. The result is a unified and flexible distributed
computing environment, where an organization can run and scale its
traditional (legacy) or cloud -native workloads on the most
appropriate c omputing model. The right PaaS solution allows
developers to build once, then deploy and mange anywhere in
a hybrid cloud environment.
5.4.3. IaaS
Infrastructure -as-a-Service, commonly referred to as simply “IaaS,” is a
form of cloud computing that delivers fundamental compute, network, and
storage resources to consumers on -demand, over the internet, and on a
pay-as-you-go basis. IaaS enables end users to scale and shrink resources
on an as -needed basis, reducing the need for high, up -front capital
expenditures or unnecessary “owned” infrastructure, especially in the case
of “spiky” workloads. In contrast to PaaS and SaaS (even newer
computing models like contain ers and serverless), IaaS provides the
lowest -level control of resources in the cloud.
IaaS emerged as a popular computing model in the early 2010s, and since
that time, it has become the standard abstraction model for many types of
workloads. However, wit h the advent of new technologies, such as
containers and serverless, and the related rise of the microservices
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99 IaaS platform and architecture
IaaS is made up of a coll ection of physical and virtualized resources that
provide consumers with the basic building blocks needed to run
applications and workloads in the cloud.
 Physical data centers: IaaS providers will manage large data
centers, typically around the world, that contain the physical
machines required to power the various layers of abstraction on top
of them and that are made available to end users over the web. In
most IaaS models, end users do not interact directly with the physical
infrastructure, but it is pro vided as a service to them.
 Compute: IaaS is typically understood as virtualized compute
resources, so for the purposes of this article, we will define IaaS
compute as a virtual machine . Providers manage the hypervisors and
end users can then programmatically provision virtual “instances”
with desired amounts of compute and me mory (and sometimes
storage). Most providers offer both CPUs and GPUs for different
types of workloads. Cloud compute also typically comes paired with
supporting services like auto scaling and load balancing that provide
the scale and performance characteristics that make cloud desirable
in the first place.
 Network: Networking in the cloud is a form of Software Defined
Networking in which traditional networking hardware, such as
routers and switches, are made available programmatically, typically
through APIs. More advanced networking use cases invol ve the
construction of multi -zone regions and virtual private clouds, both of
which will be discussed in more detail later.
 Storage: The three primary types of cloud storage are block
storage , file storage , and object storage . Block and file storage a re
common in traditional data centers but can often struggle with scale,
performance and distributed characteristics of cloud. Thus, of the
three, object storage has thus become the most common mode of
storage in the cloud given that it is highly distribut ed (and thus
resilient), it leverages commodity hardware, data can be accessed
easily over HTTP, and scale is not only essentially limitless but
performance scales linearly as the cluster grows.
Advantages
Taken together, there are many reasons why someo ne would see cloud
infrastructure as a potential fit:
 Pay-as-you-Go: Unlike traditional IT, IaaS does not require any
upfront, capital expenditures, and end users are only billed for what
they use.
 Speed: With IaaS, users can provision small or vast amount s of
resources in a matter of minutes, testing new ideas quickly or scaling
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100  Availability: Through things like multizone regions, the availability
and resiliency of cloud applications can exceed traditional
approaches.
 Scale: With seemingly limitless capacity and the ability to scale
resources either automatically or with some supervision, it’s simple
to go from one instance of an application or workload to many.
 Latency and performance: Given the broad geographic footprint of
most IaaS providers, it’s easy to put apps and services closers to your
users, reducing latency and improving performance.
5.5 AVAILABILITY MANAGEMENT
Availability is the heart of IT service management: it has the greatest
responsibility in determining IT service value . It is one of three
Information Security pillars under the C.I.A. approach. That’s why it is
understandable when customers like Andy cause a commotion if
availability isn’t treated wit h the care it should have —particularly if the
service provider is slow and unclear in communicating the incident and
resolution efforts.
According to ITIL® 4, availability is the ability of an IT service or
other configuration item to perform its agreed function when required. So,
if you can’t log in to Facebook or download your emails or access your
Salesforce dashboa rd, your immediate reaction is to deem that service
unavailable.
The purpose of availability management is to ensure that services deliver
agreed levels of availability to meet the needs of customers and users. The
more critical a service is to the customer, the more the company should
invest in its availability. We gain insights regarding the bare minimum of
what comprises availability management from the ISO/IEC 20000
standard:
 Assessing and documenting risks to service availability at regular
intervals
 Determining and documenting service availability requirements and
targets, by considering relevant business req uirements, service
requirements, SLAs , and risks
 Monitoring and recording service availability results and comparing to
targets
 Investigating and addressing instances of unplanned no n-availability
Availability management works hand -in-hand with other practices such as
architecture, change and configuration, release and deployment, and
incident and problem management in order to ensure that elements such as
capacity, continuity, and se curity are designed, built, deployed and
managed effectively across the life of the service and its underlying
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101 countless availability risks in the ITSM domain, such as expired
certific ates, poorly planned configuration changes, human error, and
vendor -related failures, among others.
Monitoring and measurement of availability must consider both the
component view (through events and alerts) as well as the customer view
(based on complain ts and usage patterns). The success of availability
management at a service level will be measured by two main metrics:
 Mean time to restore service (MTRS): How quickly your company
addresses non -availability, e.g. 4 hours
 Mean time between failures (MTBF): The frequency of non -
availability, e.g. twice a year
The focus of availability management has shifted from designing systems
that are fault tolerant (addressing MTB F) towards designing systems that
recover quickly. This has brought forward concepts such as the antifragile
software movement that thrive on vola tility and surprise. Techniques such
as auto scaling, microservices, and chaos engineering are now quite
prevalent in this area.
The Availability Manager role
While the job title Availability Manager isn’t one that stands out in
today’s age (though organiz ations do still recruit for this role), the role of
managing availability is part and parcel of ITSM environments,
particularly those of an operational n ature.
Interestingly, the European e -competence framework does not list
‘Availability’ in any title of its 40 reference dimensions or in the 30
European ICT Professional Role Profiles . A quick search, however,
reveals that availability knowledge is required in several roles and
activities:
 Architecture design
 Problem management
 Information security strategy development
 Information security management
 The data administrator role
 The DevOps expert role
Whether you’re a solution architect, software developer, systems
administrator, or service desk support specialist, availability management
will always be critical to your KPIs or OKRs. An excellent example is
the site reliability engineer (SRE) : availability is among the role’s top
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102 Availability manager tasks and responsibilities
To get an idea of expec tations for your Availability Manager, SFIA
7 defines three availability management responsibility levels, categorized
under Delivery and Operation (sub -category: Se rvice Design). These are
examples of higher responsibility, so an availability manager for these
levels would be in leadership and/or have significant expertise:
Availability management: Level 4
 Contributes to the availability management process and its op eration
and performs defined availability management tasks.
 Analyzes service and component availability, reliability,
maintainability and serviceability.
 Ensures that services and components meet and continue to meet all
agreed performance targets and serv ice levels.
 Implements arrangements for disaster recovery and documents
recovery procedures.
 Conducts testing of recovery procedures.
Availability management: Level 5
 Provides advice, assistance, and leadership associated with the
planning, design, and imp rovement of service and component
availability, including the investigation of all breaches of availability
targets and service non -availability, with the instigation of remedial
activities.
 Plans arrangements for disaster recovery together with supporting
processes and manages the testing of such plans.
Availability management: Level 6
Sets policy and develops strategies, plans, and processes for the design,
monitoring, measurement, maintenance, reporting and continuous
improvement of service and component availability, including the
development and implementation of new availability techniques and
methods.
5.6 ACCESS CONTROL
Access Control in cloud security is a system with which a company can
regulate and monitor permissions, or access to their business data by
formulating various policies suited chosen by the company. Access control
in cloud security helps companies gain macro -level visibility into their
data and user behavior, which a cloud app may not be able to offer, given
their on -demand services an d mobility.
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103 control to restrict unauthorized user access and, at the same time, give
enough access for smoot h functioning at work.
CloudCodes Access Control in cloud security lets companies formulate
policies to restrict access through specific IP addresses, browsers, devices,
and during specified time shifts. Here's an in -depth view of our Access
Control in clo ud computing solution.

5.5.1 Access Control Models
1. Discretionary Access Control (DAC) –
DAC is a type of access control system that assigns access rights based on
rules specified by users. The principle behind DAC is that subjects can
determine who ha s access to their objects. The DAC model takes
advantage of using access control lists (ACLs) and capability tables.
Capability tables contain rows with ‘subject’ and columns containing
‘object’. The security kernel within the operating system checks the t ables
to determine if access is allowed. Sometimes a subject/program may only
have access to read a file; the security kernel makes sure no unauthorized
changes occur.
Implementation –
This popular model is utilized by some of the most popular operating
systems, like Microsoft Windows file systems.

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104 2. Role -Based Access Control (RBAC) –
RBAC, also known as a non -discretionary access control, is used when
system administrators need to assign rights based on organizational roles
instead of individual user a ccounts within an organization. It presents an
opportunity for the organization to address the principle of ‘least
privilege’. This gives an individual only the access needed to do their job,
since access is connected to their job.
Implementation -
Windows and Linux environments use something similar by creating
‘Groups’. Each group has individual file permissions and each user is
assigned to groups based on their work role. RBAC assigns access based
on roles. This is different from groups since users can be long to multiple
groups but should only be assigned to one role. Example roles are:
accountants, developer, among others. An accountant would only gain
access to resources that an accountant would need on the system. This
requires the organization to const antly review the role definitions and have
a process to modify roles to segregate duties. If not, role creep can occur.
Role creep is when an individual is transferred to another job/group and
their access from their previous job stays with them.

3. Mandato ry Access Control (MAC) –
Considered the strictest of all levels of access control systems. The design
and implementation of MAC is commonly used by the government. It uses
a hierarchical approach to control access to files/resources. Under a MAC
environme nt, access to resource objects is controlled by the settings
defined by a system administrator. This means access to resource objects
is controlled by the operating system based on what the system
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105 change access control of a resource. MAC uses “security labels” to assign
resource objects on a system. There are two pieces of information
connected to these security labels: classification (high, medium, low) and
category (specific departm ent or project – provides “need to know”). Each
user account is also assigned classification and category properties. This
system provides users access to an object if both properties match. If a
user has high classification but is not part of the category of the object,
then the user cannot access the object. MAC is the most secure access
control but requires a considerable amount of planning and requires a high
system management due to the constant updating of objects and account
labels.
Implementation -
Other than the government’s implementation of MAC, Windows Vista -8
used a variant of MAC with what they called, Mandatory Integrity Control
(MIC). This type of MAC system added integrity levels (IL) to
process/files running in the login session. The IL repr esented the level of
trust the object would have. Subjects were assigned an IL level, which was
assigned to their access token. IL levels in MIC were: low, medium, high,
and system. Under this system, access to an object was prohibited unless
the user had the same level of trust, or higher than the object. Windows
limited the user to not being able to write or delete files with a higher IL.
It first compared IL levels, then moved on to checking the ACLs to make
sure the correct permissions are in place. Thi s system took advantage of
the Windows DAC system ACLs and combined it with integrity levels to
create a MAC environment.


5.7 DATA SECURITY AND STORAGE IN CLOUD
Data storage security involves protecting storage resources and the data
stored on them – both on -premises and in external data centers and the
cloud – from accidental or deliberate damage or destruction and from
unauthorized users and uses. It’s an area that is of critical importance to
enterprises because the majority of data breaches are ulti mately caused by
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106 Secure Data Storage:
Secure Data Storage collectively refers to the manual and automated
computing processes and technologies used to ensure stored data security
and integrity. This can include physical protection of the hardware on
which the data is stored, as well as security software.
Secure data storage applies to data at rest stored in computer/server hard
disks , port able devices – like external hard drives or USB drives – as well
as online/cloud, network -based storage area network (SAN) or network
attached storage (NAS) systems.

How Secure Data Storage is Achieved:
 Data encryption
 Access control mechanism at each data storage device/software
 Protection against viruses, worms and other data corruption threats
 Physical/manned storage device and infrastructure security
 Enforcement and implementation of layered/tiered storage security
architecture
Secure data storage is essential for organizations whi ch deal with sensitive
data, both in order to avoid data theft, as well as to ensure uninterrupted
operations.
Storage Vulnerabilities:
Another huge driver of interest in data storage security is the
vulnerabilities inherent in storage systems. They includ e the following:
 Lack of encryption — While some high -end NAS and SAN devices
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107 separate software or an encryption appl iance in order to make sure that
their data is encrypted.
 Cloud storage — A growing number of enterprises are choosing
to store some or all of their data in the cloud. Although some argue
that cloud storage is more secure than on -premises storage, the clou d
adds complexity to storage environments and often requires storage
personnel to learn new tools and implement new procedures in order to
ensure that data is adequately secured.
 Incomplete data destruction — When data is deleted from a hard
drive or other storage media, it may leave behind traces that could
allow unauthorized individuals to recover that information. It’s up to
storage administrators and managers to ensure that any data erased
from storage is overwritten so that it cannot be recovered.
 Lack of physical security — Some organizations don’t pay enough
attention to the physical security of their storage devices. In some
cases they fail to consider that an insider, like an employee or a
member of a cleaning crew, might be able to access physical storage
devices and extract data, bypassing all the carefully planned network -
based security measures.
Data Storage Security Principles:
At the highest level, data storage security seeks to ensure “CIA” –
confidentiality, integrity, and availability.
 Confi dentiality: Keeping data confidential by ensuring that it cannot
be accessed either over a network or locally by unauthorized people is
a key storage security principle for preventing data breaches.
 Integrity: Data integrity in the context of data storage security means
ensuring that the data cannot be tampered with or changed.
 Availability: In the context of data storage security, availability means
minimizing the risk that storage resources are destroyed or made
inaccessible either deliberately – say duri ng a DDoS attack – or
accidentally, due to a natural disaster, power failure, or mechanical
breakdown.
Data Security Best Practices:
In order to respond to these technology trends and deal with the inherent
security vulnerabilities in their storage systems , experts recommend that
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108

1. Data storage security policies — Enterprises should have written
policies specifying the appropriate levels of security for the different
types of data that it h as. Obviously, public data needs far less security
than restricted or confidential data, and the organization needs to have
security models, procedures and tools in place to apply appropriate
protections. The policies should also include details on the sec urity
measures that should be deployed on the storage devices used by the
organization.
2. Access control — Role -based access control is a must -have for a
secure data storage system, and in some cases, multi -factor
authentication may be appropriate. Administr ators should also be sure
to change any default passwords on their storage devices and to
enforce the use of strong passwords by users.
3. Encryption — Data should be encrypted both while in transit and at
rest in the storage systems. Storage administrators al so need to have a
secure key management systems for tracking their encryption keys.
4. Data loss prevention — Many experts say that encryption alone is
not enough to provide full data security. They recommend that
organizations also deploy data loss preventio n (DLP) solutions that
can help find and stop any attacks in progress.
5. Strong network security — Storage systems don’t exist in a vacuum;
they should be surrounded by strong network security systems, such
as firewalls, anti -malware protection, security gat eways, intrusion
detection systems and possibly advanced analytics and machine
learning based security solutions. These measures should prevent
most cyberattackers from ever gaining access to the storage devices.
6. Strong endpoint security — Similarly, organ izations also need to
make sure that they have appropriate security measures in place on
the PCs, smartphones and other devices that will be accessing the
stored data. These endpoints, particularly mobile devices, can
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109 7. Redundancy — Redundant storage, including RAID technology, not
only helps to improve availability and performance, in some cases, it
can also help organizations mitigate security incidents.
8. Backup and recovery — Some successful malw are or ransomware
attacks compromise corporate networks so completely that the only
way to recover is to restore from backups. Storage managers need to
make sure that their backup systems and processes are adequate for
these type of events, as well as for disaster recovery purposes. In
addition, they need to make sure that backup systems have the same
level of data security in place as primary systems.
5.8 SUMMARY
 Cybersecurity is the protection of computer systems and networks
from information disclosure, theft of or damage to their hardware ,
software , or electronic data , as well as from the disruption or
misdirection of the services they provide.

 Cloud computing provides customers with highly scalable and on-
mend computing resources. NIST specified three cloud service
models: Software as a Service (SaaS), Platform as a Service (PaaS),
Infrastructural as a Service (IaaS), each service models target a
specific need of customers.

 Authentication is the proces s for confirming the identity of the user.
The traditional authentication process allows the system to identify the
user through a username and then validate their identity through
password.

 Virtualization plays a very important role in the cloud computin g
technology, normally in the cloud computing, users share the data
present in the clouds like application etc, but actually with the help of
virtualization users shares the Infrastructure.

 Virtualization has eased many aspects of IT management but has al so
complicated the task of cyber security.The nature of virtualization
introduces a new threat matrix, and administrators need to address the
resulting vulnerabilities in their enterprise environments.

 Availability is the heart of IT service management: i t has the greatest
responsibility in determining IT service value .

 Access Control in cloud security is a system with which a company
can regulate and monitor permissions, or access to their bu siness data
by formulating various policies suited chosen by the company.

 Data storage security involves protecting storage resources and the
data stored on them – both on -premises and in external data centers
and the cloud – from accidental or deliberate damage or destruction
and from unauthorized users and uses. It’s an area that is of critical
importance to enterprises because the majority of data breaches are
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110 5.9 QUESTIONS
1. How concepts of Securit y apply in the cloud?
2. Write a short note on Authentication.
3. What are the alogorithms used for Authentication in Cloud?
4. Write a short note on Extensible Authentication Protocol -CHAP,
Lightweight Directory Access Protocol, Single Sign -on (SSO)
protocol.
5. What do you mean by Virtualization?
6. What are Virtualization System Security Issues ?
7. Write a short note on ESX and ESXi Security.
8. What are Virtualization System Vulnerabilities.
9. Write a short note on Saas, Paas, Iaas.
10. What do you mean by Availability Managemen t?
11. Write a short note on Access control
5.10 REFERENCE FOR FURTHER READING
 https://about.usps.com/handbooks/as805h/as805h_ch4.htm
 https://www.sumologic.com/glossary/cloud -computing -security/
 https://www.ijser.org/researchpaper/The -Cloud -Computing -Security -
Secure-User -Authentication.pdf
 http://www.iosrjournals.org/iosr -
jce/papers/conf.15013/Volume%204/7.%2030 -35.pdf
 http://www.techadvisory.org/2019/05/what -are-the-common -
challenges -of-virtualization/
 https://www.nakivo.com/blog/vmware -esx-vs-esxi-key-differences -
overview/
 https://docs.vmware.com/en/VMware -
vSphere/7.0/com.vmware.vsphere.security.doc/ GUID -B39474AF -
6778 -499A -B8AB -E973BE6D4899.html
 https://www.vmware.com/pdf/esx2_security.pdf
 https://searchitchannel.techtarget.com/tip/VMware -ESX -essentials -
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111  https://pentestlab.blog/2013/02/25/common -virtu alization -
vulnerabilities -and-how-to-mitigate -risks/
 https://www.investopedia.com/terms/s/software -as-a-service -saas.asp
 https://www.ibm.com/cloud/learn/paas
 https://www.bmc.com/blogs/availability -management -introduction/
 https://westoahu.hawaii.edu/cyber/best -practices/best -practices -
weekly -summaries/access -control/



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112 6
MOBILE SECURITY
Unit Structure
6.0 Objectives

6.1 Introdcution
6.2 Mobile system architectures
6.3 Overview of mobile cellular systems
6.4 GSM and UMTSSecurity & Attacks
6.5 Vulnerabilities in Cellular Services
6.6 Cellular Jamming Attacks &Miti gation
6.7 Security in Cellular VoIP Services
6.8 Mobile application security
6.9 Summary
6.10 References for reading
6.0 OBJECTIVES
1. To understand the basics of Mobile security
2. To understand Mobile application security
3. To understand the concepts which ma ily deals with the protection of
mobile devices.
4. To understand the various possible plans taken into the considerations
to protect the sensitive data or information which is stored and
transmitted by various devices such laptops, smartyphones etc.
6.1 INT RODUCTION
Mobile security or mobile device security is nothing but ensuring
protection of laptops, smartphones, and tablets from threats which is
linked with wireless computing or communications. It is nothing but a
strategy, framework, and software which is used to protect any devices
that moves with users including smartphones, phones.
6.2 MOBILE SYSTEM ARCHITECTURES [ 1]
The mobile application architecture is a collection of patterns and
techniques used to construct the whole structure of the mobile appli cation.
It is the app's backbone, determin ing how it functions. A mobile app
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113 platform, technology stack, data storage, and so on. Within an application,
the design of the mobile app architecture typically includes numerous
layers:
1. Presentation Layer
2. Business Layer
3. Data Layer
The presentation layer consists primarily of User Interface components.
The definition of the client's profile is a vital stage in building this layer so
that all of the visual elements and their layout p lease your users. Of
course, it all boils down to investigating a set of application receivers and
then turning the results into an effective UI while keeping the correct User
Experience in mind.

Fig 1: Mobile S ystem Architecture
Business layer consists of business entities, workflows, business
components, and all technical. This layer contains all of the mobile
application development tasks. Complex business procedures and policies
are also possible. There is on ly the application's façade, which include s the
core process, components, and entities, i.e. everything connected to the
app's logic and business.
Components, data utilities, and service agents comprise the data layer.
There are mainly two types of mobile architecture namely Android and
IOS mobile architecture.

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114 Activities, fragments, services, content providers, and broadcast receivers
are all common app components of an Android app. The Android OS then
utilizes this file to determine how to incorpor ate the app into the overall
user experience of the device. Because a well -written Android app
comprises several components and users frequently engage with multiple
applications in a short period of time, apps mus t adapt to various types of
user-driven wo rkflows and tasks.
The iOS application's architecture is layered. It includes an intermediary
layer between applications and hardware, preventing them from
communicating directly. In iOS, the lowest levels provide essential
services, while the upper layers create the user interface. The architecture
can be separated into four components by default: Core Operating System,
Core Services, Media, and Coca Touch.
6.3 OVERVIEW OF MOBILE CELLULAR SYSTEMS[2]
Cellular networ ks are the foundational technology for mob ile phones,
personal communication systems, wireless networking, and other devices.
The technology is being developed to replace high power
transmitter/receiver systems in mobile radio telephones. For data
transmis sion, cellular networks use lesser power, shorter range, and more
transmitters.
The following are the characteristics of cellular systems:
1. Provide extremely high capacity in a narrow spectrum.
2. Reuse of radio channels across cells.
3. Use a fixed number of cha nnels to serve an arbitrary large number o f
people by reusing the channel across the coverage region.
4. Communication is always between the mobile and the base station
(rather than directly between the mobiles).
5. Each cellular base station is given a set of r adio channels within a
small geographical area known as a cell.
6. Different channel groups are assigned to neighboring cells.
7. By restricting the coverage area to within the cell's boundary, the
channel groups can be reused to cover other cells.
8. Maintain inte rference levels at acceptable limits.
9. Reus ing frequencies or planned frequencies.
10. Wireless Cellular Network Organization.

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115 6.4 GSM AND UMTS SECURITY & ATTACKS [3]
1. Universal Mobile Telecommunications System (UMTS) : UMTS is
an abbreviation for Universal Mobil e Telecommunications System,
which was bui lt using 3GPP specifications. Its network is divided into
three major components: UE (User Equipment), Radio Access
Network (RAN), and Core Network. Based on different releases from
the 3GPP community, many technol ogies are classified as UMTS. It is
also k nown as 3G.
2. GSM (Global System for Mobile Communication) : GSM is an
abbreviation for Global System for Mobile Communication. It is the
most widely utilized mobile communication technology on the planet.
It employs time division multiple access (TDMA) to tr ansport the
digitized and reduced data along a channel with two distinct streams of
client data, each in its own time slot.
1. GSM security[4]
The modern cellular telecommunications system with the highest level of
security is GSM. The security measures us ed by GSM are specified. By
preserving call confidentiality and subscriber anonymity, GSM upholds
end-to-end security.
To protect the user's privacy, temporary identification codes are provided
to the subscriber nu mber. By using encryption methods and freq uency
hopping, which can be enabled through digital systems and signaling, the
privacy of the communication is maintained.
Using a challenge -response method, the GSM network verifies the
subscriber's identification . The MS receives a 128 -bit Random Number
(RAND). Using the unique subscriber authentication key (Ki) and the
authentication algorithm (A3), the MS calculates the 32 -bit Signed
Response (SRES) based on the encryption of the RAND. The GSM
network repeats th e calculation after receiving the SRES fro m the
subscriber to confirm the subscriber's identification.
Since it is stored in the subscriber's SIM as well as the AUC, HLR, and
VLR databases, the individual subscriber authentication key (Ki) is never
communi cated over the radio channel. If the calcu lated value and the
received SRES match, the MS has successfully authenticated and may
proceed. If the values do not match, the connection is cut off and the MS
is informed that the authentication failed.
The SIM p erforms the calculation of the signed resp onse. Because
sensitive subscriber data, like the IMSI or the unique subscriber
authentication key (Ki), is never taken out of the SIM during the
authentication process, it offers increased security.
The 64 -bit cip hering key (Kc) is generated by the cipher ing key generating
algorithm (A8), which is present in the SIM. This key is calculated by
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116 subscriber authentication key (Ki) and the same random number (RAND)
used in the authentication procedure.
The ability to alter the ciphering key in GSM adds an extra layer of
security, making the system more impenetrable to eavesdroppers. If
necessary, the ciphering key may be modified on a regular basis. Th e SIM
internally calculates the ciphering key (Kc), just like it does during the
authentication procedure. As a result, the SIM never divulges private
information like the unique subscriber authentication key (Ki).
Using the ciphering algorithm A5, encrypt ed voice and data
communications between t he MS and the network are made possible. The
GSM network's ciphering mode request instruction starts encrypted
communication. When the mobile station receives this command, it starts
encrypting and decrypting data using the ciphering key (Kc) and ciphering
algorithm (A5).
Privacy Regarding Subscriber Identity
Temporary Mobile Subscriber identification (TMSI) is used to protect
subscriber identification confidentiality. The TMSI is provided to the
mobile station afte r the authentication and encryption proces ses have been
completed. The mobile station reacts after receipt. The TMSI is effective
in the region where it was issued. The Location Area Identification (LAI),
in addition to the TMSI, is required for communicat ions outside the
location area.
2. UMTS se curity
There are four security feature groups in the UMTS specification:
1. Network access security is the collection of security tools that
guarantee users' safe access to 3G services, protecting them
specifically f rom assaults on the (radio) access link;
2. Network domain security is the collection of security tools that allow
nodes in the provider domain to safely communicate signaling data
and defend the wireline network from assaults;
3. Security measures for securing access to mobile stations are known as
user domain security.
4. Applications in the user and provider domains can securely exchange
messages thanks to a set of security characteristics called application
domain security .
Attacks(GSM and UMTS) [5] –
The secur ity mechanisms utilized in GSM networks ar e examined in this
study[5], along with network weaknesses such as SIM and SMS attacks,
encryption attack or cryptography attacks, and signaling attacks.
Following attacks are referred from this paper[5] only. They have referred
following attacks from Lord :2003 paper.
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117 1. SIM -based attacks
The GSM SIM was initially created to be as hard to tamper with, copy, or
otherwise compromise as possible. The SIM has become less secure as a
result of numerous problems that hav e been uncovered over time. The
COMP 128 t echnique can be broken to create SIM clones, which can take
up to 8 –15 hours and call for physical access to the SIM. However, it has
been shown that a device known as Dejan Karavic's SIM Scan is
frequently in use. Although 500 randomly chosen inputs shoul d have been
adequate, IBM researchers used 1000 randomly chosen inputs instead,
which cuts the time it takes to clone a SIM to only minutes or at most
seconds.
2. SMS attacks
Text messaging, also referred to as S hort Message Service (SMS), is a
major sou rce of income for any operator. People who choose to conduct
business communications, reveal passwords or secret codes for banking
operations, or receive system reports typically believe it due to a lack of
educati on.The SMS -SUBMIT format is used when send ing an SMS from
a mobile station to the service center (SC). The SC then sends a message
in SMS -DELIVER format to the recipient's mobile device.
Although the SMS -SUBMIT and SMS -DELIVER message structures
differ, t hey both follow a common standard, and the SMS -DELIVER that
follows an SMS -SUBMIT is typically predictable. A report can be
requested by the network to confirm the message was sent, as well as by
the message sender. These reports' structure is likewise qui te predictable.
It is therefore conceivabl e to send some SMS messages that do not notify
the end user but yet provide a delivery record.
3. Cryptography Attacks
It has been reported that the A5/1 or A5/2 encryption technique is used to
encrypt data on the GSM network. A5/0 has no encryption and is used in
nations where it is politically difficult to offer cryptographic gear.
Former Soviet Union nations and various Middle Eastern nations serve as
examples of this. Mathematicians and cryptography experts hav e
investigated A5/1, the supposedly strong er of the two algorithms in use,
and found that it is extremely vulnerable to cryptanalytic attacks.
There are two attacks: the Random Subgraph Attack and the Baised
Birthday Attack. While the second assault only n eeds two seconds of data
and a few minutes of processing time, the first attack needs two minutes of
data and one minute of processing (Lord: 2003). There are numerous
trade -off considerations for each of these attacks, but three of them can be
summed succ inctly.The concepts utilized in these two assaults are not only
relevant to this stream cipher but also to other stream ciphers, resulting in
novel security measures.
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118 4. Signaling attacks
Transmissions between the MS and the BTS over the air interface are
secure according to the A5 algorithms. The y can limit real -time encryption
cracking and over -the-air call interception to a certain extent. Following
the BTS, traffic is transferred within the operator's network in plain text
(www.gsmclone.net). This means that the attacker will be able to listen to
everything broadcast, including the actual phone call as well as RAND,
SRES, and Kc, if he is able to gain access to the operator's signaling
network. If the attacker has access to the GSM signaling network's SS 7
signaling protocol, it is entirely unsec ure. In addition, the attacker could
gain access to the HLR to obtain the Keys, but this is less likely given the
high level of protection associated with HLR.
6.5 VULNERABILITIES IN CELLULAR SERVICES [6]
There are six security flaws in the cellular networ k—
1. (MIB, SIB) Insecure broadcast messages
2. Measurement reports without verification
3. Insufficient cross -validation at the planning stage
4. Initiation of a random -access channel (RACH) without verification
5. A recovery me chanism is missing, and
6. Difficulty separat ing network attacks from failures
6.6 CELLULAR JAMMING ATTACKS &
MITIGATION [7]
Due to the fact that they handle even more data traffic than cellular
networks, WLANs are becoming more and more crucial. The pro tection of
WLANs from jamming attacks is c rucial given the prevalence of wireless
applications in smart settings such as smart hospitals, smart homes, and
smart buildings.[7]







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119 Table 1: Wi -Fi Jamming attacks[7]



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120 6.7 SECURITY IN CELLULAR VOIP SERVICES[8]
Following are the 12 security indicators in CellularVoIP Services
 Secure user credentials with a strong password and two -factor
authentication.
 Perform regular call log reviews for unusual call activity.
 Disable international calling / enable geo -fencing.
 Outsource to a SaaS provider for VoIP calls .
 Update firmware on VoIP phones.
 Use a router with a firewall.
 Limit physical access to networking equipment.
 Restrict user access to parts of the phone system.
 Ensure data encryption through your VoIP provider.
 Educate users on VoIP security best practic es.
 Prevent ghost calls on IP phones.
 Implement intrusion prevention systems.
6.8 MOBILE APPLICATION SECURITY[9]
Mobile Security is the need of hour; organizations, institutions and
individuals are today actively e ngaged with the mobile and similar
devices and all such devices are great threats due to many reasons.
In today's age of information technology, mobile security is crucial.
Mobile computing is extremely close to becoming there. In other words,
it is also r eferred to as the security of mobile -based technology, such as
smart phones. Attackers typically link mobile security to smartphones,
computers, and other devices. This typically includes Bluetooth, WIFI,
short message service (SMS), and multimedia messagi ng service
(MMS). However, a small number of specialists also issue warnings on
operating system security due to the possibility that attackers may make
use of various objects via browsers, OS, or malicious software. It is
important to keep in mind that do wnloading apps might occasionally
compromi se smartphone security. Applications for privacy and integrity
should be included with every smartphone or electronic device.
According to network expert the major target of the attackers are Data:
As smart phone o r electronic devices contains different ki nd of sensitive
or virtual information such as –credit card no., authentication indication,
audio, visual content, call log etc. So this is the prime target.
Identity: With an electronic device the owner can be i ndentified easily
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121 As far as modern threads are concern with mobile security; concerned
with different objects such as
1. Boot nets
2. Spyware
3. Malicious link
4. Malicious applications
There is differ ent attacking system for mobile security a nd that may
cause in the following
1. Attack based on SMS and MMS
Research in Higher Education, Learning and Administration
IQAC 2019
ISBN No.: 978 -81-941751 -0-0
SIMS Pandeshwar & Srinivas University Mukka Page 115
2. Attack based on different kind of netw ork like GSM network and
WIFI based network
3. Web browser
4. Operating system
5. Hardware and vulnerabilities
6. Insecure software etc.
In mobile security SMS is also a weak point sometime. It causes in the
mobile system having binary SMS system. It leads the denial of service
attack. We can see such witness in SIMENS S55 model having Chinese
Character. Similarly in earlier days few Nokia phones are also unable to
recognize denial of service attack. It is important to note that distributed
denial of servic e is also an important attack to the mobile and the
telecommunication system.
In mobile security another focus attacking place is GSM network. The
GSM encryption belongs to A5 algorithm and their vulnerabilities is an
important concern. We can see this kin d of attack in some of the
Europeans countries. Gradually A5/3 and A5/4 algorithm have been
popular against this kind of attack. After the development of 2G GSM
we can see the vulnerabilities. The hackers in recent past can also break
the GSM algorithm.
As far as the WIFI is concerned in recent past the attackers can get
information of a smart phone by find out the vulnerabilities. The security
of wireless network previously secured by WEP (Wired equivalent
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122 Protected Access (WPA) and WPA3 algorithm. The protocol Temporal
Key Integrity (TKIP) has been introduced to allow the migration of
WPA2 and WPA3.
In the recent past security is also an important con cern for Bluetooth
system. With Bluetooth one can easily break the vulnerabilities. The
attackers are required to connect to port for accessing or controlling the
device or mobile. In Bluetooth system attackers send a file and if users
download the file th en the system may be corrupted such as CAB IR
(SYMBIAN).
6.9 SUMMARY
In this chapter, we learnt the GSM, UMTS, vulnerabilities, jamming
attacks, mobile application security and attacks in detail. Mobile Security
as a whole necessitates various defense mecha nisms, however there are
still some problem s that make security difficult to implement. Operating
Systems are one of these few crucial ones. It is important to keep in mind
that some operating systems are single tasking, hence they cannot work
with a firew all or antivirus program.
Another essentia l issue to consider is energy independence. It is important
to remember that for security reasons, network usage shouldn't be too
high. In addition to technological defenses, it is crucial that consumers are
interested in and informed of security -related i ssues. Additionally, a few
things —rich operating systems, secure operating systems, secure
elements, and secure applications —are necessary.
6.10 REFERENCES FOR READING (REFERRED
WEBSITES)
1. https://binarapps.com/mobile -architecture -what -are-the-types/
2. https://www.tutorialspoint.com/wireless_communication/wireless_co
mmunication_cellular_networks.htm#:~:text=Cellular%20network% 2
0is%20an%20underlying%20technology%20for%2 0mobile,shorter%2
0range%20and%20more%20transmitters%20for%20data%20transmis
sion
3. https://www.geeksforgeeks.org/difference -between -umts -and-gsm/
4. https://www.tutorialspoint.com/gsm/gsm_security.htm
5. https://www.ajol.info/index.php/tim/article/view/27226
6. https://the hackernews.com/2021/12/new -mobile -
networkvu lnerabilities.html#:~:text=1%20Insecure%20broadcast%20
messages%20%28MIB%2C%20SIB%29%202%20Unverified,6%20D
ifficulty%20of%20distinguishing%20network%20failures%20from%2
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123 7. H. Pirayesh and H. Zeng, "Jamming At tacks and Anti -Jamming
Strategies in Wirele ss Networks: A Comprehensive Survey," in IEEE
Communications Surveys & Tutorials, vol. 24, no. 2, pp. 767 -809,
Secondquarter 2022, doi: 10.1109/COMST.2022.3159185.
8. https://telzio.com/blog/voip -
security#:~:text=VoIP%20Security%3A%2012%20Best%20Practices
%20for%20VoIP%20Phone,to%20parts%2 0of%20the%20phone%20s
ystem.%20More%20items
9. https://www.researchgate.net/publication/336845625_MOBILE_APPL
ICATIONS_SECURITY_AN_OVERVIEW_AND_CURRENT_TRE
ND

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124 7
SECURE WIRELESS NETWORK
Unit Structure:
7.0 Objectives
7.1 Introduction
7.2 Overview of Wireless Networks
7.3 Scanning and Enumerating 802.11Networks
7.4 Attacking 802.11 Networks
7.5 Bluetooth Scanning and Reconnaissance
7.6 Bluetooth Eavesdroppin g
7.7 Attacking & E xploiting Bluetooth
7.8 Zigbee Security & Attacks
7.9 Summary
7.10 References for reading
7.0 OBJECTIVES
1. To understand the basics of wireless network
2. To understand wireless network attacks
3. To understand how to minimize the risks of wir eless netw ork.
4. To understand how to prevent the unwanted users from accessing a
particular wireless network.

7.1 INTRODUCTION
Wireless security is the prevention of unauthori zed access or damage to
computers or d ata using wireless networks . It is used fo r standard
networks de signing, implementing, and ensu ring the security o n a wirel ess
network. It is basically used for the devices and networks that are
connected in a wireless environment .
7.2 OVERVIEW OF WIRELESS NETWORKS
Wireless networks are computer n etworks that are not wired together. The
majority of the time, radio waves are used for communication between
network nodes. They enable network connections for devices as they are
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Fig 1: Wireless Ne twork
Types of Wireless Networks
Wireless LANs − Connects two or more network devices using wireless
distribution techniques.
Wireless MANs − Connects two or more wireless LANs spreading over a
metropolitan area.
Wireless WANs − Connects large areas comprising LANs, MANs and
personal netw orks.
Due to the lack of wires and cables, it offers workspaces that are clutter -
free.
As there is no requirement for connecting devices to one another, it
promotes the mobility of network devices attached to the system.Since
there is no need to put out wi res, accessing network devices from any area
that is covered by the network or a Wi -Fi hotspot becomes
convenient.Wireless networks are simpler to install and configure.Since
new devices don't require wiring to the existing configuration, they can be
linke d to it with ease. The amount of equipment that can be added to or
withdrawn from the system can also vary greatly because they are not
constrained by the cable capacity. Because of this, wireless networks are
immensely scalable.Wireless networks don't or only use a few cables. This
lowers the expense of the setup and equipment.
7.3 SCANNING AND ENUMERATING 802.11
NETWORKS
What is 802.11 - The Institute of Electrical and Electronics Engineers
(IEEE) is responsible for maintaining the 802.11 standard, whic h
describes a link layer wireless protocol. When people hear 802.11, they
frequently assume Wi -Fi, although the two are not nearly the same. Wi -Fi
and 802.11 have become incredibly popular in recent years, and every new
laptop has a built -in Wi -Fi adapter. When the initial 802.11 standard was
ratified in 1997, transmission speeds could reach a maximum of 2 Mbps.
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126 Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS) as
two separa te physical ways for encoding information. But because these
two encoding methods are incompatible, there was a lot of uncertainty in
the market.
The IEEE published 802.11b, an update to the original 802.11 standard, in
1999. The maximum transmission speed was extended to a significantly
faster 11 Mbps by the 802.11b standard, which employed DSSS. 802.11a,
which allowed 802.11 to operate in the unlicensed 5 -GHz National
Information Infrastructure (UNII) band instead of the congested 2.4 -GHz
Industrial, Scie ntific, and Medical (ISM) band, was also introduced in
1999.
Comparative analysis of Wi -Fi and 802.11
The Wi -Fi Alliance is in charge of the 802.11 subset that makes up Wi -Fi.
Nearly all of the major wireless equipment makers felt they needed a
smaller, m ore agile group dedicated to ensuring interoperability across
vendors because the 802.11 standard is so vast and the procedure required
to change the standard can take some time (it's governed by a committee).
As a result, the Wi -Fi Alliance was founded. T he Wi -Fi Alliance
guarantees that all items with the Wi -Fi-certified emblem are compatible.
In this way, Wi -Fi Alliance establishes the "right thing" to do in the event
that any issue in the 802.11 standard arises. Additionally, it permits
suppliers to put critical portions of draft standards —standards that have
not yet been approved —into use. Wi -Fi Protected Access (WPA) is an
illustration of this.
Choose operating system - Device drivers, which are linked to a
particular operating system, are necessary fo r this hardware to
communicate with the operating system. Various wireless hacking
programs also only work on specific operating systems. When taken
together, these dependencies highlight how crucial it is to choose an
operating system.
Windows
The fact th at Windows is likely already installed on your laptop is a
benefit. Another benefit is that Windows users have access to
NetStumbler, a scanning application that is simple to set up and use.
Although NetStumbler will be explored in depth in the chapter's s ection on
tools, it's crucial to keep in mind that it's an active scanner.
Linux
The obvious choice for wireless hacking is Linux. The majority of
wireless tools were developed with Linux in mind, and it has the most
active group of driver developers. Driv ers that support monitor mode are
the rule rather than the exception on Linux. Additionally, since drivers are
open source, it is simple to patch or alter them to carry out more
sophisticated assaults. Configuring and installing unique kernel drivers
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127 of bootable CD distributions, including Knoppix -STD, Auditor, and
PHLAK, were created with security in mind.
OS X
OS X is a peculiar creature. Although the operating system's core is open ,
several of its subsystems are not. Even while I think the OS X device
driver subsystem is incredibly elegant, it isn't nearly as well known as the
Linux or any BSD driver subsystems. This indicates that there aren't many
individuals out there trying to h ack OS X device drivers. Additionally,
very few vendors offer any kind of OS X drivers at all, and if they do, they
are frequently missing functionality like monitor mode. Michael (Mick)
Rossberg, fortunately for OS X users globally, is an extremely compet ent
and driven individual when it comes creating OS X drivers.
7.4 ATTACKING 802.11 NETWORKS
Wireless network security has a rather murky history, which is really not
all that surprising given how frequently purportedly secure methods are
compromised. Howe ver, 802.11 was designed to be unique. The numerous
inventive and unrelated methods that WEP was cracked, however, set a
record for the quantity of band -aid fixes that had to be hurriedly
implemented. New methods, many of which were directly related to the
band -aid fixes, were discovered not too long after the band -aids were
used. This served as a wake -up call to the IEEE, which later produced
802.11i (also known as WPA2). Experts in the sector created 802.11i,
which fixes the majority of the issues that ha ve been identified in the
intervening years.
Several categories can be used to group wireless network defenses. The
first category —"totally ineffective," sometimes known as "security
through obscurity" —is easy to get around for anyone who is sincerely
interested in doing so.
The following defense style could be categorized as "annoying." WEP and
a WPA -PSK password created using a dictionary fall into this category.
An attacker can discover any static WEP key with enough time.
A network that requires genuine effort and some amount of talent to
infiltrate is considered to be in the third category of defense once
"annoying" security measures have been passed. Most networks aren't as
secure as this. These networks employ WPA/WPA2 that has been properly
configure d. Chapter 7 goes into great detail on the methods used to attack
properly configured WPA/WPA2 networks.
Last but not least, there are tools that can be used to attack wireless
networks in ways that are not directly linked to wireless networking,
including obtaining the WEP/WPA key from a Windows laptop without
attacking it through the wireless network. This chapter discusses attacks in
the order listed.
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128 Advanced Attacks Against WEP
RC4 Encryption Primer - RC4 encryption works by generating a stream of
random bytes. The random bytes generated are then XOR'd with the
plaintext packet, and the result is called ciphertext. Before the random
bytes are generated, RC4 must be initialized with a secret key. If two users
both use the same secret key, they will gener ate the same random bytes.
The user who receives the message can XOR the random bytes out of the
encrypted message and re -create the original.
Inductive Chosen Plaintext Attack - If an attacker knows X bytes of the
RC4 keystream generated by the secret WEP key, she can get X + 1 bytes
by guessing. Consider that an attacker watches a shared key authentication
exchange and, therefore, knows 128 bytes of RC4 output for the given IV.
The Fragmentation Attack - The attack allows for recovery of the WEP
key using the statistical attacks mentioned previously but much more
quickly. The basis for this attack is several optimizations related to
creating traffic on the local network.
7.5 BLUETOOTH SCANNING AND RECONNAISSANCE
The Bluetooth specification defines 79 chann els across the 2.4 -GHz ISM
band, each 1 -MHz wide. Devices hop across these channels at a rate of
1600 times per second (every 625 microseconds). This channel -hopping
technique is known as Frequency Hopping Spread Spectrum (FHSS), and
in current Bluetooth i mplementations, the user can get 3 -Mbps of
bandwidth with a maximum intended distance of approximately 100
meters. FHSS provides robustness against noisy channels by rapidly
moving throughout the available RF spectrum. Any set of devices wanting
to communi cate using Bluetooth needs to be on the same channel at the
same time, as shown in the illustration. Devices that are hopping in a
coordinated fashion can communicate with each other, forming a
Bluetooth piconet, the basic network model used for two or mor e
Bluetooth devices. Every piconet has a single master and between one and
seven slave devices. Communication in a piconet is strictly between a
slave and a master. The channel -hopping sequence utilized by a piconet is
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129

In the reconnaissance phase of a Bluetooth attack, we’ll examine the
process of identifyingvictim Bluetooth devices in the area through active
discovery and passive discovery, using visual inspection and hybrid
discovery. The goal of the discovery process is to identify the presence of
Bluetooth devices, revealing each device’s 48 -bit MAC address or
Bluetooth Device Address (BD_ADDR).
Once you have discovered a device, you can start to enumerate the
servi ces on the device, identifying potential exploit targets. You can also
fingerprint the remote device and leverage Bluetooth sniffing tools to gain
access to data from the piconet.
Active Device Discovery
The first step in Bluetooth reconnaissance scanning is to simply ask for
information about devices within range. Known as inquiry scanning in the
Bluetooth specification, a device can actively transmit inquiry scan
messages on a set of frequencies, listening for responses. If a target
Bluetooth device is co nfigured in discoverable mode, it will return the
inquiry scan message with an inquiry response and reveal its BD_ADDR,
timing information (known as the device clock or CLK), and device class
information (e.g., the device type such as phone, wearable devic e, toy,
computer, and so on).

Windows Discovery with BlueScanner
BlueScanner is a free tool from Aruba Networks for Bluetooth scanning
on Windows XP, Vista, and Windows 7 systems and is shown here in
action, BlueScanner uses the Microsoft Windows Bluetoot h drivers to
identify and enumerate available devices, characterizing them by name,
BD_ADDR, and available services. As an analysis tool, BlueScanner is
unique due to the simple feature of applying a location label in the scan
results, allowing you to iden tify any free -form string to describe the
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130 Double -clicking an entry in BlueScanner will open the Bluetooth Device
Information dialog, which displays the device name and BD_ADDR
information as well as detailed service information. L ocation information
can also be changed for the specific device from this dialog.
In the device summary view on the left, BlueScanner will identify the
number of devices organized by location, type (phone, headset, laptop),
and services. Clicking any indiv idual service will display only the devices
running the selected service, making it easy to identify the devices to
target with the Object Exchange (OBEX) Push Server, for example.
BlueScanner retains the logging information from past scans in a file
calle dbluescanner.dat in the same directory where the program executable
is installed. This file is a standard ASCII file, delimited by carriage return
and linefeed characters. Using standard Windows or Unix/Linux text -
handling tools, such as findstr.exe, grep, and awk, it is possible to cull data
from this file for additional reporting needs.
Passive Device Discovery
The Bluetooth specification doesn’t require that two devices wishing to
communicate gothrough the inquiry scan exchange. As a consequence, if
you determine a device’s address through some outside technique (such as
reading it in the documentation), the device has to treat your connection
the same as if you had discovered it actively.
Hybrid Discovery
When active device discovery and visual inspectio n don’t work for
identifying Bluetoothdevices, several hybrid discovery mechanisms are
also possible.
When a device manufacturer produces a product with multiple interfaces,
it must assign each interface a MAC address. Commonly, the multiple
MAC addresses on a single device are relative to each other, similar to the
first 5.5 bytes with the last nibble increased by one (for example,
00:21:5c:7e:70:c3 and 00:21:5c:7e:70:c4). This behavior has been used by
wireless intrusion detection system (WIDS) vendors to detect a rogue AP
on your network connecting through a NAT interface, by observing
commonalities between IEEE 802.11 BSSID (AP MAC address) and the
NAT MAC address observed onthe wired network. We can use similar
logic to identify the Bluetooth interface on products such as the iPhone.
Starting with the iPhone 3G, Apple issues MAC addresses to the Wi -Fi
and the Bluetooth interfaces in a one -off fashion where the Bluetooth
BD_ADDR is always one address less than the Wi -Fi MAC address. You
can observe this b ehavior on your iPhoneby tapping Settings | General |
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131 7.6 BLUETOOTH EAVESDROPPING
First, Bluetooth is based on Frequency -Hopping Spread Spectrum (FHSS),
where the transmitter and the receiver share knowledge of a pattern of
frequencies used for exch anging data. For every piconet, the frequency
pattern is unique, based on the BD_ADDR of the Bluetooth master device.
Frequency hopping at a rate of 1600 hops per second (under normal
conditions), the Bluetooth devices transmit and receive data for a short
period of time (known as a slot) before changing to the next frequency.
Under most circumstances, knowing the BD_ADDR of the piconet master
is necessary to follow along with the other devices.
Second, just knowing the BD_ADDR isn’t enough to frequency hop with
the other devices in the piconet. In addition to knowing the frequency -
hopping pattern, the sniffer must also know where in the frequency -
hopping pattern the devices are at any given time. The Bluetooth
specification uses another piece of information , known as the master clock
or CLK, to keep track of timing for the device’s location within the
channel set. This value has no relationship to the time of day; rather, it is a
28-bit value incremented by oneevery 312.5 microseconds.
Finally, Bluetooth int erfaces are simply not designed for the task of
passive sniffing. Unlike Wi -Fi monitor -mode access, Bluetooth interfaces
do not include the native ability to sniff and report network activity at the
baseband layer. You can sniff local traffic at the HCI la yer using Linux
tools such as hcidump, but this type of sniffing does not reveal lower -layer
information or activity, requires an active connection to the piconet, and
only shows activity to and from the local system.
Open -Source Bluetooth Sniffing
As an a lternative to the costly commercial tools designed for Bluetooth
sniffing, the open -source gr -bluetooth project also can be used to capture
and assess Bluetooth activity. As an open -source tool, gr -bluetooth is
tremendously useful because developers are fr ee to extend the tool’s
functionality as they see fit, unlike the rigid and limited usefulness of the
FTS4BT product.
The gr -bluetooth project is designed to take advantage of the Universal
Software Radio Peripheral (USRP) for Bluetooth traffic analysis.
In this chapter, we examined different techniques an attacker can use to
observe and eavesdrop on Bluetooth traffic through traffic sniffing. Unlike
IEEE 802.11, Bluetooth has several inherent physical layer characteristics
through the use of frequency hopp ing spread spectrum that make sniffing
difficult. Both commercial and open -source tools overcome these
challenges to varying degrees of success, cost, and complexity.Once an
attacker has established a toolkit enabling her to eavesdrop on
Bluetoothtraffic, the attacker has multiple opportunities to exploit
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132 between targets and the ability to eavesdrop on Bluetooth keyboards
configured in HID mode.
7.7 ATTACKING & EXPLOITING BLUETOOTH
Many organizations often overlook the security threat posed by Bluetooth
devices. While significant effort is spent on deploying and hardening Wi -
Fi networks through vulnerability assessments and penetration tests or
ethical hacking engagements, very little is done in the field of Bluetooth
security.Part of the reason why few organizations spend any resources on
evaluating their Bluetooth threat is a common risk misconception: “We are
indifferent about Bluetooth security because it doesn’t threaten our criti cal
assets.” Even when organizations recognize the threat Bluetooth poses,
very few people have the developed skills and expertise to implement a
Bluetooth penetration test successfully or to ethically hack a given
Bluetooth device.
Pin Attacks
Two devices may pair to derive a 128 -bit link key that is used to
authenticate the identity of the claimant device and encrypt all traffic. This
pairing exchange is protected by a PIN value up to Bluetooth 2.7.Despite
the availability of the Secure Simple Pairing (SS P) mechanism introduced
in Bluetooth 2.1, most Bluetooth users still use the legacy pairing
mechanism with PIN authentication for the initial pairing exchange. The
pairing process is a point of significant
vulnerability between the devices where an attack er who can observe the
pairing exchange can mount an offline brute -force attack against the PIN
selection. After the pairing process is complete, subsequent connections
leverage the stored 128 -bit link key for authentication and key derivation,
which is cu rrently impractical to attack.In order to crack the PIN
information, the attacker must discover the following pieces of
information:
 IN_RAND, sent from the initiator to the responder
 Two COMB_KEY values, sent from the initiator and the responder
devices
 AU_RAND, sent from the authentication claimant
 Signed Response (SRES), sent from the authentication verifier
Since the Bluetooth authentication mechanism performs mutual -
authentication (the slave authenticates to the master, and vice -versa), the
attacker has two opportunities to identify the AU_RAND and SRES
values; either exchange is sufficient, but identifying the device performing
authentication (master or slave BD_ADDR) is significant. In addition, the
attacker needs to know both the slave and master BD_A DDRs, which are
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133 BTCrack
BTCrack is a Bluetooth PIN cracking tool for Windows clients written by
Thierry Zoller. This tool is easy to use, though we’ve given it a relatively
low simplicity score, due to the challenges in capturing the pairing data
needed to crack the PIN.
7.8 ZIGBEE SECURITY & ATTACKS
The ZigBee specification includes features designed to protect the
confidentiality and integrity of wireless communications using AES
encryption and device and data authentication using a network key. To
satisfy the varying security needs of ZigBee devices, two operational
security modes have been defined:
 Standard security mode Formerly known as residential security
mode, standard security mode provi des authentication of ZigBee
nodes using a single shared key where the Trust Center authorizes
devices through the use of an Access Control List (ACL). This mode
is less resource -intensive for devices, since each device on the
network is not required to ma intain a list of all device authentication
credentials.
 High security mode Formerly known as commercial security mode,
high security mode requires that a single device in the ZigBee
network, known as the Trust Center, keep track of all the encryption
and a uthentication keys used on the network, enforcing policies for
network authentication and key updates. The Trust Center device
must have sufficient resources to keep track of the authentication
credentials used on the network and represents a single point of
failure for the entire ZigBee network, since, if it fails, no devices will
be permitted to join the network.
Zig Bee Attacks
To date, little work has been published about attacking and exploiting
ZigBee. A limited number of papers have pointed out vulne rabilities
inherent in IEEE 802.15.4 or ZigBee, but no tools have been widely
published to exploit these vulnerabilities or otherwise assess the security
of ZigBee technology. Seeing the lack of tools and techniques for
evaluating the security of ZigBee ne tworks, this author set to work in the
development of an attack tool suite designed to help people evaluate the
security of ZigBee implementations.
KillerBee is a Python -based framework for manipulating ZigBee and
IEEE 802.15.4 networks available at http: //killerbee.googlecode.com.
Written and tested on Linux systems, the project is free and open -source
with the goal of simplifying common attack tasks while empowering
other Python tools for use in exploring ZigBee security. KillerBee
includes a handful of specific attack tools developed using this
framework, both for practical attacks and to demonstrate the use of the
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Security
134 Building a KillerBee Toolkit
In order to start using the KillerBee toolkit to its full capabilities, a few
steps are necessary
for building your toolkit, including the following hardware and software:
 Atmel RZ Raven USB Stick (hardware)
 Atmel JTAGICE mkII On -Chip Programmer (hardware)
 Atmel 100 -mm to 50 -mm JTAG standoff adapter (hardware)
 50-mm male -to-male header (hardware)
 AVR Stu dio for Windows (software, free)
 KillerBee Firmware for the RZUSBSTICK (software, free)
 A Windows host for programming the RZ Raven USB Stick (one -
time operation)
Eavesdropping Attacks
Because a significant number of ZigBee networks do not employ
encryptio n, eavesdropping attacks are very useful for an attacker. Even
in the cases when the ZigBee network does use encryption, an attacker
can make use of unencrypted ZigBee frame information, such as the
MAC header, to identify the presence of ZigBee networks a nd other
important characteristics, such as the configuration of the network, node
addresses, and the PAN ID.
A handful of tools provide the ability to capture ZigBee network traffic,
ranging from inexpensive to tremendously expensive, though we’ll
provide some assistance in maximizing your investment.
Replay Attacks
The concept of a replay attack is simple: using observed data, retransmit
the frames as if the original sender were transmitting them again. The
effect of a replay attack will depend largely on the content of the data
being replayed and the nature of the protocol in use.For example, in a
network used for electronic banking, if an attacker can implement a
replay attack and re -send a bank transfer, then the funding of the original
transfer could b e doubled, tripled, or quadrupled depending on the
number of times the attacker replays the data. In the world of ZigBee
devices, a replay attack is similar with a decidedly different impact.
Encryption Attacks
Encryption key distribution, rotation, revoca tion, and management in a
ZigBee network is a challenge to address securely. As few ZigBee
devices have a Man -Machine Interface (MMI), administrators have munotes.in

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135 limited opportunity to purchase a product and configure a key locally
before provisioning the device.
Defending Against a Hardware Attack
In this attack, we highlighted steps for stealing a ZigBee device and
attacking the hardware to recover encryption key material. From a
physical security perspective, you can protect ZigBee devices against
theft through classic monitoring and theft -deterrent techniques, including
video monitoring, security guards, hardware locks, and device tethers.
These systems generally do not mix well with ZigBee, however, where a
device may be outside in an unprotected area or, in s ome cases, in the
hands of the consumer who is meant to use the system such as in retail
locations for automated checkout and payment.
7.9 SUMMARY
Wireless networks are computer networks that are not wired together. The
numerous inventive and unrelated met hods that WEP was cracked,
however, set a record for the quantity of band -aid fixes that had to be
hurriedly implemented. The Bluetooth specification defines 79 channels
across the 2.4 -GHz ISM band, each 1 -MHz wide. Devices hop across
these channels at a r ate o f 1600 times per second (every 625
microseconds).
ZigBee is a quickly growing, low -speed, and extremely low -power
utilization protocol, servicing multiple industry verticals such as
healthcare, home automation, smart -grid systems, and security systems .
While ZigBee includes mechanisms to protect data confidentiality,
frequently citing the use of AES as the miracle defense against attacks, the
vulnerabilities in ZigBee stem from the limited functionality of
inexpensive devices, which challenge defending against eavesdropping
attacks, sequence enforcement (enabling replay attacks with zbreplay), and
key provisioning (enabling key compromise with zbdsniff).
7.10 REFERENCES FOR READING
1. ADVANCED ATTACKS AGAINST WEP (luskinserver.no -ip.org) -
http://luskinserv er.no -ip.org/DOCS -
TECH/Hacking/Hacking%20Exposed/Hacking%20Exposed%20Wirel
ess/final/bbl0045.html
2. http://luskinserver.no -ip.org /DOCS -
TEC H/Hacking/Hacking%20Exposed/Hacking%20Exposed%20Wirel
ess/final/bbl0022.html
3. https://null -byte.wonderhowto.com/how -to/bt-recon -snoop -bluetooth -
devices -using -kali-linux -0165049/
4. Hacking Exposed Wireless Book
munotes.in