Computer Notes  |  JKSSB / JKPSC / FAA / Junior Assistant

Computer Virus & Antivirus — Complete JKSSB Notes
All Malware Types, Cyber Threats, PYQs & New Pattern MCQs

Virus · Worm · Trojan · Ransomware · Spyware · Rootkit · Keylogger · Antivirus · Firewall · Encryption

📌 Why This Topic is Critical for JKSSB

Computer Security is asked in every JKSSB Computer Awareness section. Questions on virus types, antivirus software, firewall, encryption and cybercrime appear across all posts — Junior Assistant, FAA, Wildlife Inspector, Graduate Level, SI Finance. Expect 3–6 questions per paper. This post covers every concept and all known PYQs.

// Jump to Section

1. What is Malware? 2. Computer Virus 3. All Malware Types 4. Comparison Table 5. Antivirus 6. Firewall 7. Encryption 8. Cyber Threats 9. All PYQs 10. New Pattern MCQs

1. What is Malware? — Introduction

Malware (Malicious Software) is any software intentionally designed to cause damage to a computer, server, network or user. The term was coined by Yisrael Radai in 1990.

🦠 Infectors

Self-replicate and attach to or infect other programs/files
→ Virus, Worm, Boot Sector Virus

🎭 Deceptive

Disguise themselves as legitimate software
→ Trojan Horse, Rootkit, Backdoor

👁️ Surveillance

Monitor/steal user data and activity
→ Spyware, Keylogger, Adware

💰 Extortion

Lock/encrypt data and demand payment
→ Ransomware, Scareware

History of Computer Viruses — Exam Timeline

Year	Virus/Malware	Significance
1971	Creeper	First self-replicating program — displayed 'I'm the creeper, catch me if you can!'
1982	Elk Cloner	First virus to spread via floppy disk — affected Apple II computers
1986	Brain	First IBM PC virus — created by Pakistani brothers Basit and Amjad Farooq Alvi
1988	Morris Worm	First internet worm — caused major disruption to ARPANET. Created by Robert Morris.
1999	Melissa Virus	Email macro virus — sent infected Word docs to first 50 Outlook contacts
2000	ILOVEYOU / Love Bug	Email worm — billions in damage. Sent from Philippines. Subject: 'ILOVEYOU'
2004	MyDoom	Fastest-spreading email worm at the time
2010	Stuxnet	World's first cyber weapon — targeted Iran's nuclear centrifuges. Created by US/Israel.
2017	WannaCry	Global ransomware attack — encrypted files, demanded Bitcoin. Affected NHS UK, 150+ countries.
2017	NotPetya	Destructive ransomware — affected Ukraine, spread globally

🎯 History PYQ Facts:
• First virus = Creeper (1971)
• First IBM PC virus = Brain (1986) — created in Pakistan
• First internet worm = Morris Worm (1988)
• ILOVEYOU = most damaging email virus (2000)
• Stuxnet = first cyber weapon targeting physical infrastructure
• WannaCry (2017) = most famous ransomware attack — demanded Bitcoin

2. Computer Virus — In Depth

A computer virus is a malicious program that attaches itself to a legitimate program or file and replicates when that file is executed. Like a biological virus, it needs a host to survive and spread. The term was coined by Fred Cohen in 1983.

Types of Computer Viruses

Virus Type	Description	Examples
File Infector Virus	Attaches to executable files (.exe, .com). Activates when infected file is run. Most common type.	CIH (Chernobyl) virus
Boot Sector Virus	Infects the Master Boot Record (MBR) — the first sector of a disk. Loads before OS. Hard to detect/remove.	Stone virus, Michelangelo
Macro Virus	Infects documents using macro programming (MS Word, Excel). Spreads via email attachments.	Melissa, Concept virus
Multipartite Virus	Infects both boot sector AND executable files — spreads through multiple paths.	Invader, Flip virus
Polymorphic Virus	Changes its own code each time it replicates — makes signature detection harder.	Storm Worm, Virut
Metamorphic Virus	Completely rewrites itself each generation — no consistent signature at all. Hardest to detect.	Zmist, Simile
Stealth Virus	Hides its presence from antivirus by intercepting system calls and masking infection.	Brain, Frodo
Resident Virus	Installs itself in computer memory (RAM) — stays active even when original program closes.	CMJ, Meve, MrKlunky
Non-Resident Virus	Does not install in memory — only active when infected file is opened.	Vienna, Cascade
Overwrite Virus	Overwrites original file content with its own code — destroys the host file.	Way, Trj.Reboot
Directory Virus	Changes directory paths so OS executes virus instead of original program.	Dir-2 virus
Web Scripting Virus	Exploits web browser and website vulnerabilities via JavaScript/HTML code.	JS/Fortnight

🎯 Most Asked Virus Types in JKSSB:
• Macro Virus = spreads through MS Office documents — most commonly asked
• Boot Sector Virus = infects MBR — loads before OS
• Polymorphic Virus = changes signature to evade antivirus
• File Infector = attaches to .exe/.com files
• Stealth Virus = hides from antivirus
• Viruses need a host file to attach to — this differentiates them from Worms

3. All Malware Types — Complete Cards

🪱 COMPUTER WORM

Definition

A worm is a standalone malicious program that replicates itself and spreads through networks without needing to attach to a host file. Unlike a virus, it does NOT need a host program — it is completely self-contained.

How it spreads

Spreads through network connections, email, shared folders, USB drives. Exploits vulnerabilities in OS/software to spread automatically without user action.

Examples

Morris Worm (1988), ILOVEYOU (2000), MyDoom (2004), Conficker (2008), WannaCry (2017)

Damage

Consumes network bandwidth, slows down systems, can deliver payloads (viruses, ransomware), can crash networks

Real-World Case

Morris Worm (1988) — first internet worm, infected 6,000 computers on ARPANET, caused millions in damage

🎭 TROJAN HORSE

Definition

A Trojan (Trojan Horse) is malware disguised as legitimate, useful software. Unlike viruses, Trojans do NOT self-replicate. They trick users into installing them by appearing to be useful programs.

How it spreads

Disguised as free software, games, utilities, email attachments, fake antivirus software, cracked applications

Examples

Zeus (banking Trojan), Emotet, TrickBot, RAT (Remote Access Trojan)

Damage

Creates backdoors, steals banking credentials, gives hackers remote access, downloads other malware

Real-World Case

Zeus Trojan — stole banking credentials from millions, caused $100 million+ in fraud

🔐 RANSOMWARE

Definition

Ransomware is malware that encrypts victim's files and demands a ransom payment (usually in cryptocurrency like Bitcoin) in exchange for the decryption key. Files become inaccessible until ransom is paid.

How it spreads

Email phishing attachments, malicious links, exploiting unpatched OS vulnerabilities, RDP (Remote Desktop Protocol) attacks

Examples

WannaCry (2017), NotPetya (2017), CryptoLocker, Locky, REvil, Ryuk, DarkSide

Damage

Complete data loss if ransom not paid, massive financial losses, disruption to hospitals/businesses/governments

Real-World Case

WannaCry (May 2017) — affected 150+ countries, NHS UK, demanded Bitcoin, exploited Windows SMB vulnerability (EternalBlue)

👁️ SPYWARE

Definition

Spyware is software that secretly monitors user activity without their knowledge or consent and sends the collected information to a remote attacker. Installed without user awareness.

How it spreads

Bundled with free software downloads, drive-by downloads from malicious websites, phishing emails

Examples

CoolWebSearch, Gator, Look2Me, Pegasus (advanced state-sponsored spyware)

Damage

Steals personal data, browsing history, login credentials, financial information. Slows system.

Real-World Case

Pegasus Spyware — developed by NSO Group, used to spy on journalists, activists, politicians worldwide

📢 ADWARE

Definition

Adware is software that automatically displays or downloads unwanted advertisements. Not always malicious but intrusive. Some adware also tracks browsing behaviour (crossing into spyware territory).

How it spreads

Bundled with free software (freeware), browser toolbar installations, deceptive download buttons

Examples

Fireball, DollarRevenue, Appearch, BrowseAd

Damage

Slow browser performance, intrusive pop-ups, browser hijacking, privacy invasion via tracking

Real-World Case

Fireball (2017) — infected 250 million computers worldwide, hijacked browsers

🕳️ ROOTKIT

Definition

A rootkit is malware designed to hide deep inside a computer system — often at the kernel/OS level — to provide persistent, hidden access to an attacker. The name comes from 'root' (highest OS privileges) + 'kit' (set of tools).

How it spreads

Often delivered by Trojans, exploits, or physical access. Modifies OS code to hide its presence from antivirus.

Examples

Sony BMG Rootkit (2005), NTRootkit, Necurs, ZeroAccess

Damage

Gives attacker complete control, hides other malware, extremely difficult to detect and remove — may require OS reinstall

Real-World Case

Sony BMG (2005) — Sony installed rootkits on music CDs that secretly installed on Windows PCs without user consent

⌨️ KEYLOGGER

Definition

A keylogger (keystroke logger) is software (or hardware) that secretly records every key pressed on a keyboard. The log is sent to the attacker, revealing passwords, credit card numbers, messages, and other sensitive data.

How it spreads

Software keyloggers: installed via Trojans/spyware. Hardware keyloggers: physical device plugged between keyboard and computer.

Examples

Family Keylogger, Revealer Keylogger (legitimate monitoring), various banking Trojans include keylogging

Damage

Steals passwords, credit card numbers, banking credentials, private messages, login details

Real-World Case

Most banking Trojans include keylogging — Zeus Trojan used keylogging to steal banking passwords

🚪 BACKDOOR

Definition

A backdoor is a secret method of bypassing normal authentication to gain unauthorised access to a computer system. Can be installed by malware or left intentionally by developers.

How it spreads

Installed by Trojans, worms, or attackers who gained initial access via other means

Examples

Back Orifice, NetBus, SubSeven, many Trojans create backdoors

Damage

Allows persistent remote access, can be used to install more malware, steal data, use system as bot

Real-World Case

Back Orifice (1998) — early backdoor tool that gave full remote control of Windows systems

😱 SCAREWARE

Definition

Scareware is malware that tricks users into thinking their computer is infected with viruses (false alerts) and pressures them to buy fake antivirus software or call a tech support scam number.

How it spreads

Pop-up ads on malicious websites, bundled with downloads, browser hijacking

Examples

WinFixer, SpySheriff, fake 'Windows Security Alert' popups

Damage

Financial loss (paying for useless software), may install actual malware, wastes time

Real-World Case

Tech support scams — fake 'Microsoft alerts' that trick users into calling scammers who then steal payment info

🤖 BOTNET / BOT

Definition

A botnet is a network of infected computers (bots/zombies) controlled remotely by an attacker (bot herder). Each infected computer is a 'bot' or 'zombie' that can be commanded without the owner's knowledge.

How it spreads

Trojans, worms, malicious downloads infect computers and connect them to a C&C (Command and Control) server

Examples

Mirai Botnet, Gameover Zeus, Conficker botnet

Damage

DDoS attacks (flooding websites), spam campaigns, cryptocurrency mining, credential stuffing

Real-World Case

Mirai Botnet (2016) — infected IoT devices (cameras, routers), launched massive DDoS taking down Twitter, Netflix, Reddit

4. All Malware Types — Master Comparison Table

Malware Type	Key Characteristic	Self-Replicates?	Spreads Automatically?	Primary Damage
Virus	Needs host file to attach to. Self-replicates when host executes. User action needed to spread.	✅ Yes (needs host)	❌ No (needs user)	Corrupts/deletes files, slows system
Worm	Standalone — no host needed. Spreads automatically through networks. Fastest spreader.	✅ Yes (standalone)	✅ Yes (automatic)	Consumes bandwidth, crashes networks, delivers payloads
Trojan	Disguised as legitimate software. Does NOT self-replicate. Needs user to install.	❌ No	❌ No (user installs)	Backdoor access, data theft, downloads more malware
Ransomware	Encrypts files and demands ransom. Most financially damaging type.	Sometimes	Varies	Complete data loss, financial ransom, business disruption
Spyware	Silently monitors user — sends data to attacker. Does NOT damage files.	❌ No	❌ No	Privacy violation, credential theft, financial fraud
Adware	Shows unwanted ads. Mildest form of malware. May track browsing.	❌ No	❌ No	Slow browser, intrusive ads, minor privacy invasion
Rootkit	Hides in OS kernel — hardest to detect. Provides persistent backdoor.	Sometimes	Varies	Undetectable persistent access, hides other malware
Keylogger	Records keystrokes. Can be software or hardware device.	❌ No	❌ No	Steals passwords, banking details, private messages
Backdoor	Secret entry point bypassing authentication. Often installed by Trojans.	❌ No	Varies	Persistent remote access by attackers
Botnet	Network of infected 'zombie' computers controlled remotely.	❌ No	Automatic via C&C	DDoS attacks, spam, crypto mining
Scareware	Fake virus alerts to trick users into buying fake security software.	❌ No	❌ No	Financial fraud, stress, may install real malware

🎯 JKSSB Key Distinctions:
• Virus needs host → Worm does NOT need host
• Trojan does NOT self-replicate — user must install it
• Ransomware = encrypts files + demands ransom
• Spyware = monitors silently — does NOT damage files
• Rootkit = hardest to detect — hides in OS kernel
• Adware = mildest — shows ads
• Keylogger = records keystrokes = steals passwords

5. Antivirus Software — Complete Coverage

An antivirus (AV) program is security software designed to detect, prevent and remove malware from a computer. Also called anti-malware in modern usage.

How Antivirus Works — Detection Methods

Detection Method	How It Works	Examples
Signature-Based Detection	Most traditional method. Antivirus maintains a virus definition database (signature database) of known malware patterns. Scans files and compares against known signatures. Advantage: Fast, accurate for known threats Disadvantage: Cannot detect NEW/unknown viruses. Requires regular updates.	Norton, McAfee (traditional scanning)
Heuristic Analysis	Analyzes code behaviour and structure to identify suspicious patterns even if the exact virus is not in the database. Looks for virus-like behaviour. Advantage: Can detect new/unknown viruses Disadvantage: False positives — may flag legitimate software	Kaspersky, Bitdefender
Behaviour Monitoring (Dynamic Analysis)	Monitors programs while they run in real-time — detects malicious behaviour like registry modifications, file encryption, or unusual network activity. Advantage: Detects zero-day threats Disadvantage: Higher system resource usage	Windows Defender, ESET
Sandbox Analysis	Runs suspicious programs in an isolated virtual environment (sandbox) to observe behaviour without risking the real system. Advantage: Very safe — real system not exposed Disadvantage: Slow, some malware detects sandboxes	Enterprise-level AV solutions
Cloud-Based Detection	Sends suspicious file hashes/data to cloud servers for analysis. Leverages collective intelligence from millions of users. Advantage: Rapid response to new threats Disadvantage: Requires internet connection	Windows Defender, Google Safe Browsing
Machine Learning / AI	Uses AI algorithms trained on millions of malware samples to predict and identify new malware without needing signatures. Advantage: Handles unknown threats well Disadvantage: Complex, resource intensive	Cylance, CrowdStrike Falcon

Popular Antivirus Software

Antivirus	Developer	Key Feature
Windows Defender	Microsoft (Built-in Windows 10/11)	Free, built-in, good for basic protection
Norton 360	NortonLifeLock	Comprehensive — antivirus + VPN + password manager
McAfee	McAfee LLC	Enterprise and consumer products
Kaspersky	Kaspersky Lab (Russia)	Excellent detection rates — some countries have restricted it
Bitdefender	Bitdefender (Romania)	High detection rates, low false positives
Avast	Avast Software	Popular free antivirus — large user base
AVG	AVG Technologies (owned by Avast)	Free antivirus with good basic protection
ESET NOD32	ESET (Slovakia)	Lightweight, fast — popular in enterprise
Quick Heal	Quick Heal Technologies (India)	Popular Indian antivirus brand
K7	K7 Computing (India)	Indian antivirus company

🎯 Antivirus PYQ Facts:
• Signature-based detection = compares against known virus database — cannot detect new viruses
• Heuristic = detects unknown viruses by suspicious behaviour patterns
• Windows Defender = built into Windows 10 and 11 — no separate install needed
• Quick Heal and K7 are Indian antivirus companies
• Antivirus database must be regularly updated to stay effective
• False positive = antivirus mistakenly flags legitimate file as malware
• Zero-day attack = attack on a vulnerability that has no patch yet

6. Firewall — Network Security

A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on pre-defined security rules. It acts as a barrier between a trusted internal network and untrusted external networks (like the Internet).

The term comes from the construction concept of a fire-resistant wall that prevents fire from spreading between sections of a building.

Types of Firewalls

Firewall Type	How It Works	Examples	Key Note
Packet Filtering Firewall	Examines packets at the network layer — checks source/destination IP address, port numbers, protocol. Simplest type. Does NOT inspect packet content.	Basic routers, early firewalls	Fast but limited inspection
Stateful Inspection Firewall	Tracks the state of network connections. Monitors full conversations, not just individual packets. More secure than packet filtering.	Most modern firewalls	Better security, more resource-intensive
Application Layer Firewall (Proxy Firewall)	Operates at application layer — understands specific protocols (HTTP, FTP, DNS). Acts as a proxy — all traffic passes through it. Deepest inspection.	Corporate firewalls	Slowest but most thorough
Next-Generation Firewall (NGFW)	Combines traditional firewall with IPS (Intrusion Prevention System), deep packet inspection, SSL inspection, and application awareness.	Enterprise security	Most comprehensive — current standard
Software Firewall	Installed on individual computers — controls per-application network access.	Windows Firewall, ZoneAlarm	Easy to deploy on endpoints
Hardware Firewall	Dedicated physical device protecting entire network. Sits between internet and network.	Cisco ASA, Fortinet, Palo Alto	Protects all devices on network

🎯 Firewall PYQ Facts:
• Firewall = barrier between trusted (internal) and untrusted (internet) networks
• Packet Filtering = simplest, checks IP/port only
• Stateful = tracks connection state — more secure
• Proxy/Application Firewall = deepest inspection
• Windows Firewall = built into Windows — software firewall
• Firewall does NOT replace antivirus — they serve different purposes
• DMZ (Demilitarised Zone) = network segment between internet and internal network

7. Encryption & Data Security

Encryption is the process of converting readable data (plaintext) into an unreadable format (ciphertext) using an algorithm and a key, so that only authorised parties can read it.

Term	Definition
Plaintext	Original readable data before encryption. e.g., 'Hello'
Ciphertext	Encrypted/scrambled unreadable data. e.g., 'X#9mK!'
Encryption	Process of converting plaintext → ciphertext using a key + algorithm
Decryption	Reverse process — converting ciphertext back to plaintext using a key
Key	Secret value used by encryption algorithm — like a password for the encryption
Cipher	The algorithm used for encryption. e.g., AES, RSA, DES
SSL/TLS	Secure Sockets Layer / Transport Layer Security — encrypts data between browser and web server (HTTPS)
HTTPS	HTTP + SSL/TLS = encrypted web browsing. Padlock icon in browser address bar.
End-to-End Encryption	Only sender and receiver can read messages — even the service provider cannot. Used in WhatsApp, Signal.
Hash Function	One-way function — converts data to fixed-length hash. Cannot be reversed. Used for password storage. e.g., MD5, SHA-256
Digital Signature	Cryptographic method to verify authenticity and integrity of a message/document
Certificate Authority (CA)	Trusted organisation that issues digital certificates — validates website identity. e.g., DigiCert, Let's Encrypt

Symmetric vs Asymmetric Encryption

Type	Description	Algorithms	Used For
Symmetric Encryption	Uses the SAME key for both encryption and decryption. Faster but key sharing is a problem.	AES (Advanced Encryption Standard) — most widely used. DES (older, weaker).	File encryption, disk encryption (BitLocker)
Asymmetric Encryption	Uses a KEY PAIR — Public Key (anyone can use) for encryption, Private Key (only owner has) for decryption. Slower but secure for key exchange.	RSA (most common), ECC (Elliptic Curve)	HTTPS, digital signatures, email encryption

🎯 Encryption PYQ Facts:
• AES = most common symmetric encryption — used in WPA2 Wi-Fi, file encryption
• RSA = most common asymmetric encryption — used in HTTPS
• HTTPS = HTTP + TLS encryption → padlock icon in browser
• MD5 = hash function (128-bit) | SHA-256 = secure hash (256-bit)
• WhatsApp uses end-to-end encryption
• BitLocker = Windows full disk encryption
• Public key = encrypts | Private key = decrypts (in asymmetric)

8. Cyber Threats, Attacks & Cybercrime

Threat/Attack	Description	Example
Phishing	Fraudulent emails/websites that impersonate legitimate organisations to steal credentials. 'Phishing' for passwords — like fishing.	Fake bank login emails, fake PayPal/Amazon notifications
Spear Phishing	Targeted phishing attack aimed at a specific individual or organisation — personalised to seem more convincing.	CEO fraud, targeted corporate attacks
Smishing	Phishing via SMS text messages — contains malicious links or phone numbers.	'Your bank account has been suspended. Click here.'
Vishing	Phishing via Voice calls — attacker pretends to be bank/tech support/government.	Fake Microsoft tech support calls, fake CBI calls
Social Engineering	Manipulating people into giving up confidential information — exploits human psychology rather than technical vulnerabilities.	Pretexting, baiting, tailgating, impersonation
DDoS Attack	Distributed Denial of Service — floods a website/server with traffic from thousands of machines (botnet) to make it unavailable.	Mirai botnet DDoS (2016) took down Twitter, Netflix
Man-in-the-Middle (MitM)	Attacker secretly intercepts communication between two parties — can read/modify data.	Public Wi-Fi attacks, ARP poisoning
SQL Injection	Inserting malicious SQL code into input fields to manipulate a database — extract, modify or delete data.	Website login forms, search boxes
Cross-Site Scripting (XSS)	Injecting malicious scripts into websites viewed by other users — steals cookies/sessions.	Forum/comment injection attacks
Zero-Day Attack	Exploiting a software vulnerability that is unknown to the vendor — no patch exists yet. Most dangerous type.	Stuxnet exploited 4 zero-day vulnerabilities
Brute Force Attack	Systematically trying every possible password combination until the correct one is found.	Password cracking tools like Hydra, Hashcat
Dictionary Attack	Uses a list of common words/passwords to crack passwords — faster than brute force.	Uses wordlists like 'rockyou.txt'
Cyber Stalking	Using internet to harass or stalk a person — online harassment.	IT Act 2000 Section 66A (India)
Identity Theft	Stealing personal information to impersonate someone for financial gain.	Using stolen Aadhaar/PAN for loans

Cybercrime Laws in India

Law / Section	Description	Punishment
IT Act 2000	Information Technology Act 2000 — India's primary cybercrime law. Amended in 2008.	Covers most cybercrimes in India
Section 43	Unauthorised access/damage to computer systems	Civil offence — compensation
Section 65	Tampering with computer source code	Up to 3 years imprisonment
Section 66	Computer-related offences (hacking)	Up to 3 years + fine
Section 66A	Sending offensive messages online	Struck down by Supreme Court in 2015 (Shreya Singhal case)
Section 66B	Receiving stolen computer resources	Up to 3 years + fine
Section 66C	Identity theft (using password/digital signature fraudulently)	Up to 3 years + ₹1 lakh fine
Section 66D	Cheating by impersonation using computer	Up to 3 years + ₹1 lakh fine
Section 66E	Violation of privacy (capturing private images)	Up to 3 years + ₹2 lakh fine
Section 66F	Cyber terrorism	Life imprisonment
Section 67	Publishing obscene material online	Up to 5 years + fine
CERT-In	Computer Emergency Response Team India — national agency for cyber security incidents	Under Ministry of Electronics & IT

🎯 Cyber Laws PYQ Facts:
• IT Act 2000 = India's main cybercrime law
• CERT-In = India's cyber security response agency
• Section 66F = Cyber Terrorism = Life imprisonment
• Section 66A was struck down by Supreme Court in 2015
• Section 66C = Identity Theft
• Phishing = fake emails to steal credentials
• DDoS = Distributed Denial of Service = floods server with traffic

9. All JKSSB PYQs — Virus, Antivirus & Cyber Security

Actual questions from JKSSB examinations across all posts.

Q1. JKSSB Graduate Level PYQ

A computer virus is:

A) A hardware component that damages RAM

B) Malicious software that attaches to a host program and self-replicates ✅

C) A type of antivirus program

D) An error in the operating system code

Answer: B — A computer virus is malicious software that attaches itself to a legitimate host program and replicates when that host is executed. The term was coined by Fred Cohen in 1983.

Q2. JKSSB Junior Assistant PYQ

Which of the following malware spreads through a network WITHOUT needing to attach to a host file?

A) Virus

B) Trojan

C) Worm ✅

D) Spyware

Answer: C — A Worm is standalone malware — it does NOT need a host file. It replicates and spreads automatically through network connections, unlike a virus which needs a host file.

Q3. JKSSB FAA PYQ

A Trojan Horse in computing is:

A) A self-replicating virus that spreads via networks

B) Malware disguised as legitimate software that does not self-replicate ✅

C) A type of antivirus program

D) A worm that infects boot sectors

Answer: B — Trojan Horse is malware disguised as useful, legitimate software. Unlike viruses and worms, Trojans do NOT self-replicate — they depend on users being tricked into installing them.

Q4. JKSSB Wildlife Inspector 2026 PYQ

Ransomware is a type of malware that:

A) Monitors user activity and sends data to attackers

B) Displays unwanted advertisements

C) Encrypts the victim's files and demands ransom for decryption key ✅

D) Records keystrokes to steal passwords

Answer: C — Ransomware encrypts files on the victim's computer, making them inaccessible, and demands payment (usually cryptocurrency like Bitcoin) for the decryption key. WannaCry (2017) is the most famous example.

Q5. JKSSB Graduate Level PYQ

Spyware is malware that:

A) Destroys files and corrupts data

B) Secretly monitors user activity and sends data to a remote attacker ✅

C) Encrypts files and demands ransom

D) Replicates through network connections

Answer: B — Spyware silently monitors user activity — browsing history, keystrokes, login credentials — and transmits this information to a remote attacker, all without the user's knowledge.

Q6. JKSSB Graduate Level PYQ

Which type of malware is hardest to detect because it hides in the OS kernel?

A) Virus

B) Worm

C) Adware

D) Rootkit ✅

Answer: D — Rootkits are designed to hide deep in the operating system (often at kernel level) — they can mask their presence from antivirus software by intercepting OS calls. They are the hardest malware to detect and remove.

Q7. JKSSB Accounts Assistant PYQ

A Keylogger records:

A) The screen content of a computer

B) Network traffic passing through a router

C) Every keystroke typed on a keyboard ✅

D) File access timestamps

Answer: C — A keylogger (keystroke logger) records every key pressed on a keyboard — capturing passwords, credit card numbers, messages and any typed data. The collected data is sent to the attacker.

Q8. JKSSB Graduate Level PYQ

The first computer virus for IBM PCs was:

A) Creeper

B) Morris Worm

C) Brain ✅

D) ILOVEYOU

Answer: C — Brain (1986) was the first virus for IBM PC computers. It was created by brothers Basit and Amjad Farooq Alvi from Pakistan to protect their software from piracy. It infected floppy disk boot sectors.

Q9. JKSSB Wildlife Inspector 2026 PYQ

WannaCry (2017) is an example of:

A) Spyware

B) Adware

C) Ransomware ✅

D) Trojan

Answer: C — WannaCry is ransomware — it encrypted files on infected computers across 150+ countries in May 2017 and demanded Bitcoin payment. It exploited the EternalBlue vulnerability in Windows SMB protocol.

Q10. JKSSB Junior Assistant PYQ

Antivirus software that detects malware by comparing file code against a database of known malware patterns uses:

A) Heuristic analysis

B) Signature-based detection ✅

C) Behavioural monitoring

D) Sandbox analysis

Answer: B — Signature-based detection maintains a database of known malware signatures (patterns) and compares files against it. It is fast and accurate for known threats but cannot detect new/unknown viruses.

Q11. JKSSB FAA PYQ

Which detection method allows antivirus to identify unknown/new viruses by analysing suspicious behaviour?

A) Signature-based detection

B) Heuristic analysis ✅

C) Blacklisting

D) Whitelisting

Answer: B — Heuristic analysis examines code structure and behaviour patterns to identify suspicious activity that resembles malware — even if the exact virus is not in the signature database. This allows detection of new, unknown threats.

Q12. JKSSB Graduate Level PYQ

A firewall is used to:

A) Speed up internet connection

B) Remove viruses from infected files

C) Monitor and control network traffic based on security rules ✅

D) Encrypt data stored on hard disk

Answer: C — A firewall monitors and controls incoming and outgoing network traffic based on pre-configured security rules. It acts as a barrier between trusted internal networks and untrusted external networks (internet).

Q13. JKSSB Panchayat Secretary PYQ

Phishing is a type of cyber attack that:

A) Floods a website with traffic to make it unavailable

B) Uses fraudulent emails/websites to trick users into revealing sensitive information ✅

C) Injects malicious code into a database

D) Intercepts network communications

Answer: B — Phishing uses fake emails, websites or messages that impersonate legitimate organisations (banks, government agencies) to trick users into providing passwords, credit card numbers, or other sensitive data.

Q14. JKSSB Graduate Level PYQ

DDoS stands for:

A) Direct Denial of System

B) Distributed Denial of Service ✅

C) Dynamic Data over Server

D) Distributed Data of Service

Answer: B — DDoS = Distributed Denial of Service. It is an attack that floods a server/website with overwhelming traffic from thousands of compromised machines (botnet), making the service unavailable to legitimate users.

Q15. JKSSB FAA PYQ

Which Indian law primarily governs cybercrimes?

A) Indian Penal Code 1860

B) Information Technology Act 2000 ✅

C) Cyber Security Act 2012

D) Digital India Act 2015

Answer: B — The Information Technology Act 2000 (IT Act 2000), amended in 2008, is India's primary legislation governing cybercrime and digital activities. It defines offences like hacking, identity theft, and cyber terrorism.

Q16. JKSSB Junior Assistant PYQ

Which of the following is the built-in antivirus in Windows 10 and 11?

A) Norton Antivirus

B) McAfee

C) Quick Heal

D) Windows Defender ✅

Answer: D — Windows Defender (now called Microsoft Defender Antivirus) is the built-in security software in Windows 10 and Windows 11. It provides real-time protection without needing a separate installation.

Q17. JKSSB Graduate Level PYQ

HTTPS is more secure than HTTP because:

A) It loads web pages faster

B) It uses SSL/TLS encryption for data transmission ✅

C) It does not require a password

D) It is only used for government websites

Answer: B — HTTPS (HTTP Secure) uses SSL/TLS (Secure Sockets Layer/Transport Layer Security) to encrypt data transmitted between the browser and web server. The padlock icon in the browser address bar indicates HTTPS.

Q18. JKSSB Wildlife Guard PYQ

A Macro Virus infects:

A) The Master Boot Record of a hard disk

B) Executable (.exe) files only

C) Documents like MS Word and Excel files that support macros ✅

D) Only image files

Answer: C — Macro viruses infect documents that support macro programming — primarily MS Word (.doc/.docx) and Excel (.xls/.xlsx) files. They execute when the infected document is opened. Melissa (1999) was a famous macro virus.

Q19. JKSSB Accounts Assistant PYQ

Quick Heal and K7 are examples of:

A) Indian antivirus software companies ✅

B) Types of computer viruses

C) Network firewalls

D) Encryption algorithms

Answer: A — Quick Heal Technologies (Pune) and K7 Computing (Chennai) are Indian antivirus/cybersecurity companies. This is a commonly asked 'Indian context' question in JKSSB.

Q20. JKSSB Graduate Level PYQ

Which of the following best describes a Botnet?

A) A type of antivirus software

B) A network of infected computers controlled remotely by an attacker ✅

C) A secure private network

D) A type of firewall

Answer: B — A botnet is a network of computers (called bots or zombies) that have been infected with malware and are remotely controlled by an attacker. Used for DDoS attacks, spam sending, cryptocurrency mining.

10. New Statement-Based Pattern MCQs

JKSSB 2026 new pattern — evaluate multiple statements simultaneously as seen in Wildlife Inspector paper.

Q1. JKSSB New Pattern STATEMENT BASED

Which of the following statements about computer malware are CORRECT?

I. A virus requires a host file to attach to, while a worm does not

II. A Trojan Horse self-replicates and spreads automatically through networks

III. Ransomware encrypts victim's files and demands payment

IV. Spyware secretly monitors user activity without their knowledge

A) I, III and IV only ✅

B) All of the above

C) I and II only

D) II and IV only

Answer: A — Statements I, III, IV are correct. Statement II is WRONG — Trojan Horse does NOT self-replicate. It is disguised as legitimate software and needs the user to install it. Worms self-replicate automatically.

Q2. JKSSB New Pattern STATEMENT BASED

Identify the INCORRECT statements about antivirus detection methods:

I. Signature-based detection can detect new/unknown viruses not in its database

II. Heuristic analysis detects malware by suspicious behaviour patterns

III. Sandbox analysis runs suspicious programs in an isolated environment

IV. Windows Defender requires a separate purchase for Windows 10 users

A) I and IV only ✅

B) II and III only

C) I only

D) All are correct

Answer: A — Statements I and IV are INCORRECT. Signature-based detection CANNOT detect new/unknown viruses — that's its main limitation (needs heuristic for that). Windows Defender is FREE and BUILT-IN to Windows 10/11.

Q3. JKSSB New Pattern STATEMENT BASED

Which statements about cyber attacks are CORRECT?

I. Phishing uses fake emails to trick users into revealing passwords

II. DDoS attacks flood a server with traffic to make it unavailable

III. A Man-in-the-Middle attack requires physical access to the computer

IV. Zero-day attacks exploit vulnerabilities that have no patch yet

A) I, II and IV only ✅

B) All of the above

C) I and III only

D) II, III and IV only

Answer: A — Statements I, II, IV are correct. Statement III is WRONG — Man-in-the-Middle attacks do NOT require physical access; they can be performed remotely by intercepting network traffic (e.g., on public Wi-Fi).

Q4. JKSSB New Pattern STATEMENT BASED

Consider the following about firewalls and select the CORRECT statements:

I. A firewall monitors and controls network traffic based on security rules

II. Packet Filtering Firewall examines packets at the network layer checking IP and port

III. A firewall is the same as an antivirus — both perform identical functions

IV. Windows Firewall is a built-in software firewall in Windows

A) I, II and IV only ✅

B) All of the above

C) I and III only

D) II and IV only

Answer: A — Statements I, II, IV are correct. Statement III is WRONG — Firewall and Antivirus serve DIFFERENT purposes. Firewall controls network traffic; Antivirus detects and removes malware from files.

Q5. JKSSB New Pattern STATEMENT BASED

Which statements about WannaCry ransomware are CORRECT?

I. WannaCry was a ransomware attack in 2017

II. WannaCry demanded payment in Bitcoin cryptocurrency

III. WannaCry was created by the Indian government to test security

IV. WannaCry affected over 150 countries including NHS UK

A) I, II and IV only ✅

B) All of the above

C) I and III only

D) II, III and IV only

Answer: A — Statements I, II, IV are correct. Statement III is COMPLETELY WRONG — WannaCry was NOT created by India. It exploited a leaked NSA hacking tool (EternalBlue) and spread globally affecting hospitals, banks, and governments.

Q6. JKSSB New Pattern STATEMENT BASED

Identify the CORRECT statements about encryption:

I. AES is a widely used symmetric encryption algorithm

II. In asymmetric encryption, the public key encrypts and private key decrypts

III. HTTPS uses SSL/TLS encryption

IV. MD5 is an encryption algorithm that can be reversed to get original data

A) I, II and III only ✅

B) All of the above

C) I and IV only

D) II, III and IV only

Answer: A — Statements I, II, III are correct. Statement IV is WRONG — MD5 is a HASH function (one-way), NOT an encryption algorithm. Hash functions CANNOT be reversed to get original data. That's the fundamental difference between hashing and encryption.

⚡ Quick Revision — Most Exam-Tested Facts

Malware Types

• Virus = needs host, self-replicates
• Worm = no host, spreads via network
• Trojan = disguised, NO self-replicate
• Ransomware = encrypts files + ransom
• Spyware = silent monitoring
• Rootkit = hides in OS kernel
• Keylogger = records keystrokes
• Adware = shows unwanted ads

Antivirus

• Signature = known threats only
• Heuristic = unknown threats
• Windows Defender = built-in Win 10/11
• Quick Heal, K7 = Indian AV
• False positive = legit file flagged
• Zero-day = no patch exists yet
• Regular updates = essential!

Famous Attacks

• Brain (1986) = first IBM PC virus
• Morris Worm (1988) = first internet worm
• ILOVEYOU (2000) = email worm
• Stuxnet (2010) = first cyber weapon
• WannaCry (2017) = famous ransomware
• Mirai (2016) = IoT botnet DDoS

Security Concepts

• Firewall ≠ Antivirus (different roles)
• HTTPS = HTTP + TLS encryption
• AES = symmetric, RSA = asymmetric
• Phishing = fake emails for creds
• DDoS = flood server with traffic
• IT Act 2000 = India's cybercrime law
• CERT-In = India's cyber agency

Tags

#JKSSB#ComputerVirus#Antivirus#Malware#Ransomware#Trojan#Worm#Spyware#Rootkit#Keylogger#Firewall#Encryption#CyberSecurity#Phishing#DDoS#WannaCry#ITAct2000#JKPSC#FAA2026#JuniorAssistant#JKEdusphere#ComputerNotes