Government Polytechnic Palanpur

Information & Communication Technology

Progressive Assessment I (September - 2025) - Solutions

Semester: 5
Subject Name & Code: Cyber Security (4353204)
Date: 04/09/2025
Time: 11:30 AM TO 12:30 PM
Total Marks: 20

Question 1: Answer the following questions [10 Marks]

Question 1(a) [7 marks]

Explain various security attacks, mechanisms, and services associated with each layer of the OSI model.

Answer:

OSI Security Framework:

OSI Security Framework

Layer	Attacks	Mechanisms	Services
Physical	Wiretapping, Jamming	Physical security, Shielding	Access control
Data Link	MAC flooding, ARP poisoning	Encryption, Authentication	Frame integrity
Network	IP spoofing, Routing attacks	IPSec, Firewalls	Packet filtering
Transport	Session hijacking, SYN flooding	SSL/TLS, Port security	End-to-end security
Session	Session replay, Hijacking	Session tokens, Timeouts	Session management
Presentation	Data corruption, Format attacks	Encryption, Compression	Data transformation
Application	Malware, Social engineering	Antivirus, User training	Application security

Key Security Services:

Authentication: Verifying user identity
Authorization: Controlling access permissions
Non-repudiation: Preventing denial of actions
Data integrity: Ensuring data accuracy

Mnemonic: "All People Seem To Need Data Protection"

Question 1(b) [3 marks]

Describe CIA triad with example.

Answer:

CIA Triad Components:

CIA Triad

Component	Definition	Example
Confidentiality	Protecting data from unauthorized access	Password protection on bank accounts
Integrity	Ensuring data accuracy and completeness	Digital signatures on documents
Availability	Ensuring systems are accessible when needed	24/7 online banking services

Confidentiality: Only authorized users can access sensitive information
Integrity: Data remains accurate and unaltered during transmission
Availability: Systems remain operational and accessible to legitimate users

Mnemonic: "CIA Keeps Information Safe"

Question 2: Answer the following questions [10 Marks]

Question 2(a) [7 marks]

Explain working of packet filter and application proxy.

Answer:

Firewall Type	Working
Packet Filter	Examines packet headers based on predefined rules. Makes decisions based on source/destination IP addresses, ports, and protocols. Works at OSI network and transport layers. Offers high-speed filtering with low resource usage.
Application Proxy	Acts as intermediary between client and server applications. Processes all traffic at application layer. Creates two connections (client-to-proxy and proxy-to-server). Provides content inspection and user authentication capabilities.

Diagram:

Packet Filter vs Application Proxy

Key Differences:

Feature	Packet Filter	Application Proxy
Speed	Fast	Slower
Security	Basic	Advanced
Resource Usage	Low	High
Content Inspection	Header only	Full content

Mnemonic: "Packets Check Headers, Proxies Check Content"

Question 2(b) [3 marks]

What is authentication? Explain different methods of authentication.

Answer:

Authentication Definition: Process of verifying user identity before granting system access.

Authentication Methods:

Authentication Methods

Method	Description	Example
Password	Something you know	PIN, passphrase
Biometric	Something you are	Fingerprint, iris
Token	Something you have	Smart card, USB key

Single-Factor: Uses one authentication method
Multi-Factor: Combines multiple methods
Two-Factor (2FA): Uses exactly two factors

Mnemonic: "Password Biometric Token Authentication"

Alternative Set Questions

Alternative Q1: Answer the following questions [10 Marks]

Alternative Q1(a) [7 marks]

Explain MD5 hashing and Secure Hash Function (SHA) algorithms.

Answer:

Hash Function Comparison:

Hash Function Process

Feature	MD5	SHA-1	SHA-256
Output Size	128 bits	160 bits	256 bits
Security Level	Weak	Weak	Strong
Speed	Fast	Moderate	Slower
Current Status	Deprecated	Deprecated	Recommended

MD5 Algorithm Process:

Input Processing: Message is padded and divided into 512-bit blocks
Initialization: Sets up four 32-bit registers with fixed values
Compression: Processes message in 16-word blocks through four rounds of operations
Output: Produces 128-bit digest as final hash value

SHA Algorithm Features:

Deterministic: Same input produces same hash
Avalanche Effect: Small input change causes major hash change
One-way Function: Cannot reverse hash to original data
Collision Resistant: Difficult to find two inputs with same hash

Applications:

Password storage and verification
Digital signatures and certificates
Data integrity verification

Mnemonic: "Hash Always Produces Same Output"

Alternative Q1(b) [3 marks]

Explain Public key and Private Key cryptography.

Answer:

Public Key Cryptography (Asymmetric):

Public Key Cryptography

Key Characteristics:

Feature	Public Key	Private Key
Distribution	Freely shared	Kept secret
Usage	Encryption/Verification	Decryption/Signing
Security	Can be public	Must be protected

Public Key: Used for encryption and signature verification
Private Key: Used for decryption and digital signing
Security: Based on mathematical complexity (RSA, ECC algorithms)

Example: In RSA encryption, if Alice wants to send Bob a message:

Alice encrypts with Bob's public key
Only Bob can decrypt using his private key

Mnemonic: "Public Encrypts, Private Decrypts"

Alternative Q2: Answer the following questions [10 Marks]

Alternative Q2(a) [7 marks]

Explain different types of malicious software and their effect.

Answer:

Malware Classification:

Malware Classification

Type	Behavior	Effect	Example
Virus	Attaches to files	File corruption	Boot sector virus
Worm	Self-replicating	Network congestion	Conficker worm
Trojan	Disguised malware	Data theft	Banking Trojans
Ransomware	Encrypts files	Data hostage	WannaCry
Spyware	Monitors activity	Privacy breach	Keyloggers
Adware	Shows unwanted ads	Performance degradation	Pop-up ads
Rootkit	Hides presence	System compromise	Kernel rootkits

Effects on Systems:

Performance: Slow system response
Data: Loss, corruption, or theft
Privacy: Unauthorized monitoring
Financial: Direct monetary loss

Prevention Methods:

Regular antivirus updates
Safe browsing practices
Email attachment caution
System security patches

Mnemonic: "Viruses Worms Trojans Really Steal All Resources"

Alternative Q2(b) [3 marks]

What is firewall? List out types of firewalls.

Answer:

Firewall Definition: Network security device that monitors and controls incoming/outgoing traffic based on security rules.

Firewall Architecture

Types of Firewalls:

Type	Function	Level
Packet Filter	Examines packet headers	Network Layer
Stateful	Tracks connection state	Transport Layer
Application Proxy	Inspects application data	Application Layer
Personal Firewall	Protects individual devices	Host-based

Hardware Firewall: Dedicated network appliance
Software Firewall: Installed on individual computers
Cloud Firewall: Delivered as a service (FWaaS)

Mnemonic: "Firewalls Protect Networks Always"

Legend:

CO1, CO2: Course Outcomes
A: Apply level
U: Understand level