Virus Awareness

Jul. 1, 2002

The term virus is an all-encompassing term used to describe a program that infects your computer. There are three categories that the ‘viruses’ fall into. 

1. Virus – A virus is a program that reproduces itself and spreads to other computers and files. A virus requires action by the person using the computer, which can be anything from opening an attachment to downloading and running a program that contains a virus. 

2. Worm – A worm is a type of virus that reproduces itself but does not need to be activated to run. Worms infect a computer by finding a way in through email or other programs, infecting the files on that computer, and then sending itself back out to other computers. 

3. Trojan Horse – A trojan horse installs a ‘backdoor’ on your machine that allows another person to gain access or control of your computer. Trojan horses often hide in other programs and install themselves without the user knowing.

There are four types of viruses that can infect your computer. 

1. Boot – This virus infects the startup procedure of your computer. 

2. Operating System – This virus infects and usually alters your operating system (i.e. Windows, Macintosh, Linux, etc.) causing it to become unstable or not load at all. 

3. Application – This virus will infect a program on your machine and cause it to do things it is not supposed to. An example is a virus infecting your email and sending out messages to everyone in your address book. This is the most common virus type. 

4. Macro – This virus infects programs that run macros such as Word and Excel.

Viruses can be categorized into two categories based on the damage they cause - Non-Destructive & Destructive. 

A non-destructive virus does not actually destroy any data or hardware. These types of viruses are usually more annoying than damaging. An example would be the Yankee Doodle virus. Once a computer was infected with this virus it would randomly play Yankee Doodle anytime the computer was on. 

A non-destructive virus can also be embarrassing. There are numerous viruses that send themselves out to people in your address book saying that there are naked pictures of you or someone else attached. While this virus does not damage data or hardware you may consider it damaging to your reputation. 

A destructive virus does exactly as it sounds. It destroys something. It could be data, hardware, or a combination of both. 

Destructive viruses are the most costly. A destructive virus can simply destroy files or cause hardware to fail, but it can also be more sinister. A destructive virus may send out confidential information contained on your machine or network. The virus writer can direct this information to your competitors who can then use this information against you. A destructive virus may also change information in the files that it infects. This can be very damaging if it changes sales figures in your budget for example. 

As you can see virus infection can be costly. Not only in damage to files and hardware but in the time it takes to track the virus down and clean the infection. In fact according to Computer Economics, viruses attacks on Information Systems around the world, including clean-up costs and lost productivity, caused over $10.7 billion dollars worth of damage last year.