Home AHC RO/ARO Computer Knowledge Basic Cyber Security Viruses

Basic Cyber Security Viruses

Comprehensive, high-yield study notes, mnemonics, tables, and concept breakdown for Allahabad High Court RO/ARO preparation.

1. Core Concepts: Malware & Viruses

  • Malware (Malicious Software): Umbrella term for any software designed to harm, disrupt, or gain unauthorized access to a computer system.
  • Virus: A type of malware that attaches itself to legitimate programs or documents and spreads to other computers when those programs/documents are executed. It requires a host program to replicate.
  • Infection Vector: How viruses spread, e.g., infected email attachments, malicious websites, USB drives, pirated software.
  • Payload: The malicious action a virus performs (e.g., deleting files, displaying messages, slowing down system).

High-Yield Fact: Malware vs. Virus

All viruses are malware, but not all malware are viruses. Malware is the broader category.

2. Common Virus Types & Characteristics

  • Boot Sector Virus: Infects the Master Boot Record (MBR) or boot sector of a hard drive/removable media. Activates when the system boots up.
  • Program/File Infector Virus: Attaches to executable files (.exe, .com, .dll). Activates when the infected program runs.
  • Macro Virus: Written in a macro language (e.g., VBA) and embedded in data files (e.g., MS Word .doc, Excel .xls). Spreads when the infected document is opened and macros are enabled.
  • Polymorphic Virus: Changes its code/signature each time it replicates, making it harder for antivirus software to detect.
  • Stealth Virus: Tries to hide its presence from antivirus software by intercepting system calls and presenting uninfected versions of files.
Virus Type Primary Target Detection Challenge
Boot Sector MBR/Boot Sector Early system startup
Macro Document files (e.g., .doc, .xls) Requires macro execution
Polymorphic Executable files Signature-based detection

3. Other Key Malware Types (Non-Virus)

  • Worm: Self-replicating malware that spreads independently across networks without needing a host program or user interaction. Consumes bandwidth.
  • Trojan Horse: Disguises itself as legitimate software. Once executed, it performs malicious actions (e.g., creating backdoors, stealing data). Does NOT self-replicate.
  • Spyware: Secretly collects information about user activity (e.g., browsing habits, keystrokes) and sends it to a third party.
  • Adware: Displays unwanted advertisements, often bundled with free software. Can track browsing.
  • Ransomware: Encrypts a user's files and demands a ransom (usually cryptocurrency) for their decryption.

Exam Tip: Virus vs. Worm vs. Trojan

  • Virus: Needs a host, replicates.
  • Worm: Independent, self-replicates over network.
  • Trojan: Disguised, does NOT self-replicate.

4. Prevention, Detection & Landmark Facts

  • Antivirus Software: Detects, prevents, and removes malware. Uses signature-based detection, heuristic analysis, and behavioral monitoring.
  • Firewall: Monitors and controls incoming/outgoing network traffic based on predefined security rules. Acts as a barrier.
  • Regular Updates: Keeping OS, applications, and antivirus definitions up-to-date patches vulnerabilities.
  • Safe Browsing: Avoiding suspicious links, attachments, and untrusted websites.

Memory Aid: Virus Prevention (U-SAFE)

  • Update Software Regularly
  • Scan with Antivirus
  • Avoid Suspicious Links/Attachments
  • Firewall Enabled
  • Educate Yourself

Important Landmark Facts:

  • First PC Virus (in the wild): Elk Cloner (1982) for Apple II, spread via floppy disks.
  • First PC Virus (MS-DOS): Brain (1986), a boot sector virus.
  • First Antivirus Software: G Data Anti-Virus (1987) and Dr. Solomon's Anti-Virus Toolkit (1988).
  • Famous Worm: ILOVEYOU (2000) - spread via email, caused billions in damages.

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High-Yield Revision Points

Review these essential summary takeaways right before your examination:

📌 Focus on foundational definitions, statutory provisions, and landmark dates related to Basic Cyber Security Viruses.
📌 Compare key differences and table classifications to eliminate incorrect options in preliminary MCQs.
📌 Regularly revise mnemonics and memory keywords to recall complex facts under timed test conditions.

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