Computer virus

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Computer viruses are small software programs designed to spread from one computer to another in a manner that interferes negatively with a computer's operation.

Computer virus is a recent phenomenon with the first ever computer virus surfacing in 1982. Called Elk Cloner, it was created and distributed on an Apple II computer, and targeted personal computers.


Why should I be aware of this?

  • A computer virus might corrupt or delete data on your computer, use your e-mail program to spread itself to other computers, or even erase everything on your hard disk.
  • Knowing more about computer viruses can be a useful tool to learn how to deal with viruses. So if you are interested in working in computer security then learning about how malicious software works is a must.
  • A virus can have a devastating effect, disrupting productivity and doing billions of dollars in damages.
  • On the other hand, they show us how sophisticated and interconnected human beings have become.
  • Viruses are most easily spread by attachments in e-mail messages or instant messaging messages. Never open e-mail attachments unless you know who it is from and you are expecting it.
  • Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files.
  • Viruses also spread through downloads on the Internet.

All about computer virus

Computer viruses are similar to biological viruses. They multiply in number and need a host to survive. Like their biological counterparts, computer virus also requires a cause, which like a weak immune system can be an expired anti-virus program. This facilitates the entry and spread of the virus.

There are three basic types of viruses that you will likely encounter.

  1. Trojan Horses --The Trojan virus does not reproduce. Once it enters you computer, it makes your computer susceptible to malicious intruders and allows them to access and read your files. Avoid downloading programs or files from sites if you are not 100 % positive of what the file or program does.
  2. Worms -- A Worm is a virus program that can copy and multiply itself once it enters a computer. It does not need any further effort by the virus maker. It uses computer networks and security flaws. Worms usually attack multi-user systems such as Unix environments. They can spread over corporate networks via the circulation of emails. Once multiplied, the copied worms scan the network for further loopholes and flaws in the network. A classic example of a worm is the ILOVEYOU virus.
  3. Email Viruses-- Email viruses spread through email messages. An email virus can automatically forward itself to thousands of people. To avoid receiving virus-laden emails, always check that your antivirus software is up-to-date and also stay clear of opening attachments you were not expecting or do not know anything about. It can even be from you friends.

Features of a virus

A computer virus is a type of legitimate program. There are three main parts of a virus

  1. Replicator - The primary aim of this part of the virus is ensuring its survival. Its job is not to inflict damage on the system but attach themselves to legitimate programs in the machine. They ensure that each time the program is run then the virus will 'wake up' and start to reproduce.
  2. Concealer - This part of the virus has the job of hiding the virus. It uses a number of methods to do this but the point is if you don't know a virus is there then you wont try and kill it.
  3. Payload - If a virus intends to have a long life then any damage it causes must either be very slight or not take place for a long period after infection to avoid early detection and ensuring maximum spread and damage.

What can we do?

To help avoid viruses, it is essential

  • You keep your computer current with the latest updates and antivirus tools.
  • Stay informed about recent threats
  • Follow a few basic rules when you surf the Internet, download files, and open attachments.
    • Stop downloading pirated music / videos / software.
    • Stop borrowing software/MP3s etc downloaded by your friends.
    • Have a clear policy on using all portable media.
    • Know how to browse safely on the Internet.
  • If you think your computer is not infected, immediately get a good antivirus program.


  • Virus ahead: stay clear
  • What is computer virus?
  • The Anatomy of A Computer Virus
  • Viruses – Types and Examples
  • The Common Types of Computer Viruses