Cybersecurity protects systems, networks, devices, data and services from unauthorised access, disruption, manipulation and destruction. Exam questions often distinguish malware types and attack methods.

• Virus: malicious code that attaches to a host/program and normally requires execution of the infected host/program to spread.
• Worm: standalone malware that can self-propagate across networks.
• Trojan horse: malicious software disguised as legitimate/useful software; it does not behave like a self-replicating worm.

Phishing uses deceptive messages/sites to steal information. Spear phishing targets a specific person or group; whaling targets high-value/senior persons; vishing uses voice/phone; smishing uses SMS. Baiting uses an attractive lure; pretexting uses a fabricated story.

DoS aims to make a service unavailable; DDoS distributes the attack across multiple systems. A Man-in-the-Middle attack involves secretly intercepting or manipulating communication between parties.

Brute force tries many password combinations; dictionary attack uses lists of common passwords; credential stuffing reuses stolen credentials on other services; password spraying tries a common password across many accounts; SQL injection targets database queries; XSS injects malicious scripts into web pages; zero-day attacks exploit a vulnerability before an effective patch is available.

Ransomware can lock or encrypt data and demand payment. Modern campaigns may also steal data and threaten disclosure. Other terms include rootkit, backdoor, botnet, scareware, fileless malware and cryptojacking.

Firewall filters/controls network traffic using rules. Antivirus detects known malware and may quarantine infected files. Sandboxing isolates suspicious programs. Backups, patching, strong authentication and user awareness reduce risk.

CERT-In is the national agency for responding to cybersecurity incidents. NCIIPC focuses on protection of critical information infrastructure. I4C coordinates efforts against cybercrime. NCCC supports monitoring and coordination in cyberspace. Cyber Swachhta Kendra supports botnet/malware detection and cleaning.

The IT Act provides a legal framework for electronic records, digital signatures/electronic authentication, e-governance and specified computer-related offences. For exam preparation, learn the section → subject pair rather than trying to memorise every penalty.

Section 66A was struck down by the Supreme Court in Shreya Singhal v. Union of India (2015). Do not learn it as a currently enforceable offence. It is a classic exam trap because older study material may still list it.

Cyber crimes may be classified by target: individuals (identity theft, harassment, impersonation), property (fraud, piracy, IP theft) and government/critical systems (defacement, attacks on public infrastructure).

Cyber forensics involves identifying, collecting, preserving, analysing and presenting digital evidence. The key principle is maintaining evidence integrity and documenting handling.

Use strong unique passwords, multi-factor authentication, updated software, safe backups and caution with links/attachments. For exam MCQs, first identify the attack type, then the target, then the defensive measure or legal section.