INTRODUCTION TO CRYPTOGRAPHY & SECURITY

UNIT-1
P.RAMA SANTOSH NAIDU
ASSISTANT PROFESSOR
MVGR(A)-CSE
SUBJECT
(CRYPTOGRAPHY AND INFORMATIOON SECURITY)
INTRODUCTION TO CRYPTOGRAPHY & SECURITY

P.RAMA SANTOSH NAIDU, MVGR(A)-CSE
Introduction to cryptography & Security
Definitions of Threat, attack, security attacks and types, Security Services and categories, Security
mechanisms, A model for network security, internet standards. Buffer overflow and format string
vulnerabilities, TCP Session hijacking, ARP Attacks, man-in-the-middle attacks, SQL injection, Phishing
attacks.
TOPICS TO BE COVERED
2

Threat:
A potential for violation of security, which exists when there is a circumstance, capability, action, or event that
could breach security and cause harm. That is, a threat is a possible danger that might exploit a vulnerability.
Attack:
An assault on system security that derives from an intelligent threat; that is, an intelligent act that is a
deliberate attempt (especially in the sense of a method or technique) to evade security services and violate the
security policy of a system.
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4
S.NO THREAT ATTACK
1 Can be intentional or unintentional Is intentional
2 May or may not be malicious Is malicious
3 Circumstance that has ability to cause damage Objective is to cause damage
4 Information may or may not be altered or damaged Chance for information alteration and damage is very high
5 Comparatively hard to detect Comparatively easy to detect
6 Can be blocked by control of vulnerabilities Cannot be blocked by just controlling the vulnerabilities
7 Can be initiated by system itself as well as outsider Is always initiated by outsider (system or user)

Security Attacks:
Any action that compromises the security of information owned by an organization.
Types of Security Attacks:
SECURITY ATTACKS
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TYPES OF ATTACKS
PASSIVE
ATTACKS
ACTIVE
ATTACKS
Release of
Message
Contents
Traffic
Analysis
masquerade Modification of messages
Replay
Repudiation
Denial of
Service

1. Passive Attacks
A Passive attack attempts to learn or make use of information from the system but does not affect system
resources. Passive Attacks are in the nature of eavesdropping on or monitoring transmission. The goal of the
opponent is to obtain information that is being transmitted.
2. Active Attacks
An Active attack attempts to alter system resources or affect their operations. Active attacks involve some
modification of the data stream or the creation of false statements.
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SECURITY ATTACKS

1. Passive Attacks
Release of Message Contents Traffic analysis
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SECURITY ATTACKS

2. Active Attacks
Masquerade Modification of messages
8
SECURITY ATTACKS

2. Active Attacks
Repudiation
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SECURITY ATTACKS

2. Active Attacks
Replay Denial of Service
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SECURITY ATTACKS

P.RAMA SANTOSH NAIDU, MVGR(A)-CSE 11
SECURITY SERVICES
A processing or communication
service that enhances the security of
the data processing systems and the
information transfers of an
organization. These services are
intended to counter security attacks,
and they make use of one or more
security mechanisms to provide the
service. Following are the five
categories of these services:
SECURITY
SERVICES

SECURITY MECHANISMS
SPECIFIC SECURITY MECHANISMS
May be incorporated into the appropriate
protocol layer in order to provide some of the
OSI security services.

RELATIONSHIP BETWEEN SECURITY SERVICES & SECURITY MECHANISMS

MODEL FOR NETWORK SECURITY

INTERNET STANDARDS
Internet Standard: These are technically matured standards that define the protocols and formats of messages.
The fundamental standards are those which form the Internet Protocol (IP).
The organizations of Internet Standards are
1. Internet Engineering Task Force (IETF)
2. Internet Society (ISOC)
3. Internet Architecture Board (IAB)
4. Internet Research Task Force (IRTF)
5. World Wide Web Consortium (W3C)

BUFFER OVERFLOW VULNERABILITIES
BUFFER OVERFLOW
A buffer overflow attack takes place when an attacker manipulates the
coding error to carry out malicious actions and compromise the affected
system. The attacker alters the application’s execution path and overwrites
elements of its memory, which amends the program’s execution path to
damage existing files or expose data.
A buffer overflow attack typically involves violating programming languages
and overwriting the bounds of the buffers they exist on. Most buffer
overflows are caused by the combination of manipulating memory and
mistaken assumptions around the composition or size of data.

TYPES OF BUFFER OVERFLOW ATTACKS
✓ Stack overflow attack
✓ Heap overflow attack
✓ Integer overflow attack
✓ Unicode overflow

How to prevent buffer overflow attacks?
✓ Choose programming language wisely.
✓ Avoid risky library files
✓ Validate input
✓ Filter malicious input
✓ Test applications pre-deployment
✓ Enable runtime protections
✓ Use executable space protection

FORMAT STRING VULNERABILITIES
#include <stdio.h>
void main(int argc, char **argv)
{
// This line is safe
printf("%sn", argv[1]);
// This line is vulnerable
printf(argv[1]);
}
Safe Code
The line printf("%s", argv[1]); in the example is safe, if you compile the program
and run it:
./example "Hello World %s%s%s%s%s%s"
The printf in the first line will not interpret the “%s%s%s%s%s%s” in the input
string, and the output will be: “Hello World %s%s%s%s%s%s”
Vulnerable Code
The line printf(argv[1]); in the example is vulnerable, if you compile the program
and run it:
./example "Hello World %s%s%s%s%s%s"
The printf in the second line will interpret the %s%s%s%s%s%s in the input
string as a reference to string pointers, so it will try to interpret every %s as a
pointer to a string, starting from the location of the buffer (probably on the Stack).
At some point, it will get to an invalid address, and attempting to access it will
cause the program to crash.

TYPES OF FORMAT STRING ATTACKS
✓ Denial of Service Attacks(DoS)
✓ Writing Attacks
✓ Reading Attacks

PREVENTING FORMAT STRING VULNERABILITIES
✓ Always specify a format string as part of program, not as an input. Most format string vulnerabilities are
solved by specifying “%s” as format string and not using the data string as format string
✓ If possible, make the format string a constant. Extract all the variable parts as other arguments to the
call. Difficult to do with some internationalization libraries

BUFFER OVERFLOW AND FORMAT STRING VULNERABILITIES
Description Buffer Overflow Format String
Vulnerabilities
Number of exploits 1000s 10s
Consideration Security Threat Programming Bug
Level of Techniques Advanced Basic
Visible Nature Difficult to spot Easy to find

TCP SESSION HIJACKING
TCP SESSION HIJACKING
TCP session hijacking is a
security attack on a user
session over a protected
network.

ARPATTACKS
An ARP spoofing, also known as ARP poisoning, is
a Man in the Middle (MitM) attack that allows
attackers to intercept communication between network
devices.

MAN IN THE MIDDLE ATTACKS
A Man-in-the-Middle (MITM) attack happens when a
hacker inserts themselves between a user and a website.
This kind of attack comes in several forms. For example, a
fake banking website may be used to capture financial login
information. The fake site is “in the middle” between the
user and the actual bank website.

✓ IP spoofing
✓ DNS spoofing
✓ HTTPS spoofing
✓ SSL hijacking
✓ Email hijacking
✓ Wi-Fi eavesdropping
✓ Stealing browser cookies

✓ IP spoofing
IP Spoofing is the creation of IP
packets with a forged source IP
address. This is often done for the
purpose of concealing the identity of
the sender or impersonating another
computing system.

✓ DNS spoofing
Domain Name Server (DNS) spoofing
(a.k.a. DNS cache poisoning) is an
attack in which altered DNS records
are used to redirect online traffic to a
fraudulent website that resembles its
intended destination.

✓ HTTPS spoofing
HTTPS is one of the ways users know
that their data is “safe.” The S stands
for secure. At least that is what an
attacker wants you to think. Attackers
set up HTTPS websites that look like
legitimate sites with valid
authentication certificates, but the
URL will be just a bit different.

✓ SSL hijacking
In the process, when the user tries to login to the web
application, the server sets a temporary remote
cookie in the client’s browser to authenticate the
session. This enables the remote server to remember
the client’s login status.

✓ Email hijacking
Email hijacking is another form of man-in-
the-middle attack, in which the hacker
compromises and gain access to a target’s
email account. The attacker then silently
monitors the communications between the
client and the provider and uses the
information for malicious purposes.

✓ Wi-Fi eavesdropping
WiFi Eavesdropping can involve a hacker
stealing data while on a public, unsecured wifi
network. The unsecured transmission of data
allows for the theft of anything that’s
unencrypted, from passwords to files to
financial information (both personal and
business-related).

✓ Stealing browser cookies
▪ To understand the risk of stolen browser cookies, you need to understand what one is. A browser
cookie is a small piece of information a website stores on your computer.
▪ For example, an online retailer might store the personal information you enter and shopping cart items
you’ve selected on a cookie so you don’t have to re-enter that information when you return.
▪ A cybercriminal can hijack these browser cookies. Since cookies store information from your browsing
session, attackers can gain access to your passwords, address, and other sensitive information.

SQL INJECTION
SQL Injection (SQLi) is an injection attack where an
attacker executes malicious SQL statements
to control a web application’s database server,
thereby accessing, modifying and deleting
unauthorized data.

SQL INJECTION

SQL INJECTION
How to prevent SQL Injection?
✓ Regular Scanning
✓ Training & Awareness
✓ Filter User Input
✓ Use Whitelist-based Filters
✓ Use Updated Web Technologies

PHISHING ATTACK
“Phishing” refers to an attempt to steal
sensitive information, typically in the form
of usernames, passwords, credit card
numbers, bank account information or
other important data in order to utilize or
sell the stolen information. By
masquerading as a reputable source with an
enticing request, an attacker lures in the
victim in order to trick them, similarly to
how a fisherman uses bait to catch a fish.
Types of Phishing Attacks:
1. Spear Phishing
2. Clone Phishing
3. Cat Phishing
4. Voice Phishing
5. SMS Phishing

THANK YOU!
P.RAMA SANTOSH NAIDU
ASSISTANT PROFESSOR
MVGR(A)-CSE
43

INTRODUCTION TO CRYPTOGRAPHY & SECURITY

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