📑 Topics on this page (Jump to Topic):
📌 1. Malware
| Type | Feature |
|---|---|
| Virus | Attaches to a file/program and spreads; activates when run |
| Worm | Spreads by itself over networks, without a host file |
| Trojan Horse | Looks like a useful program but does hidden harm |
| Spyware / Keylogger | Secretly steals information/keystrokes |
| Adware | Shows unwanted ads |
| Ransomware | Encrypts files and demands ransom — WannaCry (2017) |
| Rootkit / Backdoor | Keeps hidden access |
| Botnet | Network of infected computers (bots/zombies) |
- First experimental self-replicating program: Creeper (1971). First PC (MS-DOS) virus: Brain (1986).
- VIRUS is popularly expanded as "Vital Information Resources Under Siege".
- Antivirus: Quick Heal (Indian), Norton, McAfee, Kaspersky, Windows Defender.
⚠️ Exam Traps:
- A worm needs no host file; a virus does.
- A Trojan does not self-replicate — the user installs it.
📌 2. Cyber Attacks & Safeguards
| Attack | Meaning |
|---|---|
| Phishing | Stealing passwords or bank details through fake e-mails/websites |
| Vishing / Smishing | Fraud through phone calls / SMS |
| DoS / DDoS | Flooding a server with traffic to stop service |
| Spoofing | Pretending to be another identity/address |
| Man-in-the-middle | Secretly reading/changing communication between two parties |
| Social engineering | Exploiting human trust to get information (e.g. asking for an OTP) |
| SQL Injection | Injecting harmful SQL into a website's input |
| Hacking (black/white hat) | Unauthorised access; white hat = ethical hacker |
| Safeguard | Function |
|---|---|
| Firewall | Blocks/allows network traffic by rules (hardware or software) |
| Encryption | Plain text → cipher text; decryption reverses it |
| Symmetric / Asymmetric | One shared key / public-private key pair (RSA) |
| Digital Signature | Proves authenticity and integrity; based on asymmetric cryptography |
| 2FA / MFA | Password + OTP/biometric |
| CAPTCHA | Tells humans and bots apart |
| VPN | Encrypted secure tunnel over a public network |
- Backup: full (everything), incremental (changed since the last backup of any kind), differential (changed since the last full backup). 3-2-1 rule: 3 copies, 2 different media, 1 off-site.
- Strong password: at least 8–12 characters with upper/lower case, digits and symbols. Never share OTPs/PINs.
⚠️ Exam Traps:
- CAPTCHA = Completely Automated Public Turing test to tell Computers and Humans Apart.
- Incremental: since the last backup of any kind; differential: since the last full backup.
📌 3. IT Act 2000 & Cyber Law
- Information Technology Act 2000 — in force from 17 October 2000; based on the UNCITRAL model law; covers e-commerce, digital signatures and cyber crime. Major amendment in 2008.
| Section | Subject |
|---|---|
| 43 | Damage to a computer/copying data without permission — compensation |
| 65 | Tampering with computer source documents |
| 66 | Computer-related offences (hacking) |
| 66A | Offensive messages — struck down by the Supreme Court in 2015 (Shreya Singhal case) |
| 66C | Identity theft (misuse of passwords, digital signatures) |
| 66D | Cheating by personation using a computer |
| 66E | Violation of privacy (private images) |
| 66F | Cyber terrorism — up to life imprisonment |
| 67 / 67A / 67B | Publishing obscene / sexually explicit / child sexual material electronically |
| Body/facility | Fact |
|---|---|
| CERT-In | India's national cyber incident response agency (2004), under MeitY |
| Cyber crime helpline | 1930 (financial fraud); portal cybercrime.gov.in |
| DPDP Act 2023 | Digital Personal Data Protection Act, 2023 |
⚠️ Exam Traps:
- Section 66A is no longer in force (struck down in 2015).
- Cyber terrorism = 66F; identity theft = 66C.
📌 4. Practice MCQs
📝 Practice MCQs (prepared by SF Prep — not PYQs)
Q1. Malware that spreads by itself over a network without a host file is a: Practice
Correct answer: (B)
A worm copies itself independently; a virus needs a host.
A worm copies itself independently; a virus needs a host.
Q2. Malware that looks like a useful program but does hidden harm is a: Practice
Correct answer: (C)
Named after the wooden horse of Troy.
Named after the wooden horse of Troy.
Q3. Malware that encrypts files and demands a ransom is: Practice
Correct answer: (D)
WannaCry (2017) was a well-known ransomware.
WannaCry (2017) was a well-known ransomware.
Q4. A program that secretly records the keys pressed on a keyboard is a: Practice
Correct answer: (A)
A keylogger is a kind of spyware that can steal passwords.
A keylogger is a kind of spyware that can steal passwords.
Q5. Trying to steal bank details through fake e-mails/websites is called: Practice
Correct answer: (B)
Phishing = baiting users, like fishing, to capture information.
Phishing = baiting users, like fishing, to capture information.
Q6. Phishing done through SMS is called: Practice
Correct answer: (C)
Smishing = SMS + phishing; vishing = voice (calls).
Smishing = SMS + phishing; vishing = voice (calls).
Q7. An attack that floods a server with traffic from many sources to stop its service is: Practice
Correct answer: (D)
DDoS = Distributed Denial of Service, often using a botnet.
DDoS = Distributed Denial of Service, often using a botnet.
Q8. A system that blocks or allows network traffic based on rules is a: Practice
Correct answer: (A)
A firewall can be hardware or software.
A firewall can be hardware or software.
Q9. Converting plain text into unreadable cipher text is called: Practice
Correct answer: (B)
Encryption = plain → cipher; decryption = cipher → plain.
Encryption = plain → cipher; decryption = cipher → plain.
Q10. Using an OTP along with a password is an example of: Practice
Correct answer: (C)
2FA = two different proofs — something you know + something you have.
2FA = two different proofs — something you know + something you have.
Q11. The main purpose of CAPTCHA is to: Practice
Correct answer: (D)
CAPTCHA stops automated bots from filling forms.
CAPTCHA stops automated bots from filling forms.
Q12. A backup of all files changed since the last full backup is called: Practice
Correct answer: (A)
Differential = since the last full; incremental = since the last backup of any kind.
Differential = since the last full; incremental = since the last backup of any kind.
Q13. When did India's Information Technology Act come into force? Practice
Correct answer: (B)
The IT Act 2000 came into force on 17 October 2000; it was amended significantly in 2008.
The IT Act 2000 came into force on 17 October 2000; it was amended significantly in 2008.
Q14. Which section of the IT Act deals with cyber terrorism? Practice
Correct answer: (C)
Section 66F — punishable with up to life imprisonment.
Section 66F — punishable with up to life imprisonment.
Q15. Section 66C of the IT Act relates to: Practice
Correct answer: (D)
66C = fraudulent use of passwords, digital signatures, etc.
66C = fraudulent use of passwords, digital signatures, etc.
Q16. Which IT Act section was struck down by the Supreme Court in the Shreya Singhal case (2015)? Practice
Correct answer: (A)
Section 66A (offensive messages) was held to violate free speech.
Section 66A (offensive messages) was held to violate free speech.
Q17. India's national agency for responding to cyber security incidents is: Practice
Correct answer: (B)
CERT-In (2004) works under the Ministry of Electronics and IT.
CERT-In (2004) works under the Ministry of Electronics and IT.
Q18. The national helpline number for reporting financial cyber fraud is: Practice
Correct answer: (C)
Helpline 1930 and the cybercrime.gov.in portal.
Helpline 1930 and the cybercrime.gov.in portal.
Q19. Which is regarded as the first PC (MS-DOS) virus? Practice
Correct answer: (D)
Brain (1986) was written by two brothers in Pakistan. Creeper (1971) was the first experimental self-replicating program.
Brain (1986) was written by two brothers in Pakistan. Creeper (1971) was the first experimental self-replicating program.
Q20. What is used to prove the authenticity and integrity of an electronic document? Practice
Correct answer: (A)
A digital signature is based on public-private key (asymmetric) cryptography; the IT Act gives it legal recognition.
A digital signature is based on public-private key (asymmetric) cryptography; the IT Act gives it legal recognition.