Ch 5 : Computer Virus

1. What is a Computer Virus?

A Computer Virus is a harmful computer program written by humans to damage, steal, or slow down data inside a computer system.

Example of Computer Virus:
ILOVEYOU, MyDoom, WannaCry, and Stuxnet etc
Full Form of VIRUS:
Vital Information Resources Under Seize

Common Symptoms of an Infected Computer:

  • Runs very slowly.
  • Shows sudden pop-up messages
  • Files or folders disappear automatically.
  • Computer restarts on its own.

2. Who Created the First Computer Virus and Why?

The First Virus: Creeper (1971)

  • Creator: Bob Thomas
  • Why it was created: It was built as an experimental test to see if a program could automatically move between different computers. It was not meant to destroy data—it simply printed the message: "I'm the creeper, catch me if you can!"

The First PC Virus: Brain (1986)

  • Creators: Two brothers from Pakistan, Basit Farooq Alvi and Amjad Farooq Alvi.
  • Why it was created: To protect their medical software from illegal copying (piracy). It unexpectedly spread globally via floppy disks.

3. How Does a Computer Virus Spread?

Computer viruses cannot spread by themselves without a carrier path. They spread through these primary channels:

Transmission Channel How It Spreads
Infected USB Drives Plugging an infected pen drive or hard drive into a clean computer.
Email Attachments Opening suspicious file attachments sent by unknown senders.
Unsafe Downloads Downloading free movies, cracked games, or software from untrusted websites.
Pirated Software Installing pirated or modified software that contains hidden viral code.

4. How to Prevent Computer Viruses

  • Use Genuine Antivirus: Install and regularly update reliable security software.
  • Scan External Drives: Always scan USB drives before opening files.
  • Avoid Unknown Links: Do not click on suspicious links or download random attachments from emails.
  • Keep Software Updated: Regularly update the computer's Operating System (e.g., Windows Updates) to fix security weaknesses.
  • Backup Data: Store important files on external drives or cloud storage like Google Drive.

5. Antivirus Software, Uses, and Examples

Antivirus Software is a specialized security program designed to detect, block, and remove computer viruses and malware.

Key Functions:

  1. Real-time Protection: Scans files automatically as they are opened or downloaded.
  2. System Scanning: Checks all hard drive files for existing infected code.
  3. Quarantine & Removal: Isolates infected files to keep them from spreading, then cleans or deletes them.

Popular Antivirus Examples:

  • Windows Defender (Built into Windows OS)
  • Kaspersky Antivirus
  • Avast Free Antivirus
  • Quick Heal
  • Norton Security
Group A: Multiple Choice Questions (MCQs) Tick (✓) the correct answer: 1. What does the letter 'V' stand for in the acronym VIRUS? (a) Virtual (b) Vital (c) Valuable (d) Visual 2. Which was the world's first experimental computer virus? (a) Brain (b) Trojan (c) Creeper (d) Windows Defender 3. Why was the "Brain" virus created in 1986? (a) To steal money from bank (b) To stop software piracy (c) To shut down the interne (d) To delete school files 4. Which of the following is NOT a method through which a virus spreads? (a) Using an infected USB flash drive (b) Downloading pirated games (c) Typing a document in Microsoft Word (d) Opening unknown email attachments 5. What is the primary job of an Antivirus program? (a) Increase typing speed (b) Clean and protect the computer from viruses (c) Connect the computer to Wi-Fi (d) Edit images and videos Group B: Match the FollowingGroup B (Match): 1-C, 2-E, 3-D, 4-B, 5-A
Column A Column B
1. Creeper A. Built-in security tool in Windows
2. Brain B. Stops unauthorized access and cleans viruses
3. USB Drive C. Created by Bob Thomas in 1971
4. Antivirus Software D. Common hardware path for viral spread
5. Windows Defender E. First PC virus created by two brothers in Pakistan
Group C: Short Answer Questions 1. Define a computer virus in simple words. 2. List any two common signs that show a computer is infected by a virus. 3. Write two safe practices to protect your computer from virus attacks. 4. Name any three popular antivirus programs. ***** The End *****
Hint Group A (MCQs): 1-(b), 2-(c), 3-(b), 4-(c), 5-(b) Group B (Match): 1-C, 2-E, 3-D, 4-B, 5-A Group C (Sample Short Answers): Q1. A computer virus is a harmful human-made program that damages, slows down, or steals data from a computer. Q2: (1) Computer runs very slowly. (2) Files disappear automatically or strange pop-up errors appear. Q3: (1) Always scan USB drives before opening files. (2) Keep genuine antivirus software installed and updated. Q4: Windows Defender, Kaspersky, Avast, Quick Heal, or Norton.
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