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There are various ways  in which viruses can attack computer system;

  • When you download or open attachment in e-mail message or by instant messaging messages
  • Installing unknown program from unreliable and suspicious looking web sites
  • Illegal duplication of software from one computer to another e.g. computer games etc.
  • When you use infected flask h drive or CD-ROMS or DVD on your system
  • Viruses can be transmitted from one computer to another e.g through infected diskettes
  • Viruses can infect your computer when you download from the internet
  • Virus infection can happen through an infection flash disk, hard disk or optical disk. Computers on internet are more prone to virus infection as different types of virus are constantly released and can be downloaded easily into the system.
  • Another source of infection can be bad handling of the computer which can cause critical system malfunction e.g. exposing the computer to heat source, severe power fluctuation etc.

 Virus Warning Signs

  1. Slowing down of the response time
  2. Presence of tiny dots.
  3. Wandering across the screen.
  4. Incomplete saving of file.
  5. Corruption of the system set-up instruction.
  6. Appearance of strange characters.
  7. It can cause organized program into a disorganized program and making them not to execute.
  8. It destroys the partition task file, even the entire system of hard drive.
  9. Causes damage to valuables stored on any storage media.
  10. Causing machine to stop and suddenly restarting itself.
  11. Sudden disappearance of programs and applications from the system without deletion.
  12. New windows keep opening up at an alarming rate.

Preventing Computer Virus

  1. A good and reliable antivirus should be installed.
  2. Avoid suspicious websites that attempt to install and run a program on your system.
  3. Install anti-spyware and anti-malware programs.
  4. Scan any e-mail attachment you want to view and open.
  5. Watch your download from the internet e.g. music, video and any other items.
  6. Install firewalls.
  7. Set-up automatic virus scan.
  8. Update antivirus regularly.
  9. Stay away from cracked software and be prepared to lock down anytime you hear of a new virus.


Computer Antivirus

 Antivirus is a program developed to destroy computer virus wherever it is found in the system. Examples of antivirus software are:

  1. Norton antirust
  2. McAfee virus scan
  3. Dr Solomon Trolled
  4. Pennicillin
  5. Microsoft Antivirus
  6. Check point Antivirus
  7. Central point Antivirus
  8. Avast
  9. Karpersky
  10. E-scan

 General Evaluation:

  1. Mention five examples of computer virus. 2. State five sources of virus infect micro computer..
  2. State seven virus warning sign. 4. State five ways of preventing computer virus.


Understanding Data Processing for senior secondary schoolsby Dinehin Victoria pages 290 – 292


  1. Virus warning sign include the following except ……………(a) Presence of tiny dots.(b) Incomplete saving of file. (c) e-scan            (d)  Slowing down of the response time
  2. ………… deletes the information contained in the files.
  • Fat virus (b) micro virus  (c) Overwrite virus     (d) Polymorphic virus
  1. …………………. prevent access to certain section of the disk where important files are stored and the damage caused can result in information losses from individual files or entire directories (a) Polymorphic virus (b) micro virus      (c) overwrite virus       (d) Fat virus
  2. ………… a program developed to destroy computer virus.
  • Anti virus (b) malware     (c) spyware      (d) virus
  1. ……………… consumes or occupy a large part of computer memory thereby causing network servers and individual computers to stop responding.
  • Trojan horse (b) worm          (c) spyware      (d) malware



  1. Define computer virus.
  2. State three ways in which virus can infect micro computer.
  3. State five sources of virus infect micro computer..
  4. State five ways of preventing computer virus.
  5. State five examples of anti virus

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