Different types of computer infections and a history of some of the worst culprits.

The Trojan Horse, so named because you often take it into your system because it presents itself as a welcome gift rather than a menace, can completely eradicate your system, it can allow the theft of your information and it can allow key-logging of your computer. Often, Trojan Horses pose as programmes that you should download to protect you from a virus risk, so cunning are their producers.

Some of the Worst Viruses

1. Melissa was a worm that attacked computers in 1999. The first fifty names of a users email contact list were sent an infected document. This worm proliferated uncontrollably, causing untold damage to business.

2. The Chernobyl virus dates back to 1998. It attacked the computer’s memory and eventually deleted all files on the computer’s hard disk.

3. Slammer caused havoc in 2003, infecting over half a million computer servers, which, in turn, affected the operation of a multitude of computers.

4. Sobig.F was a virus that spread through the Outlook Express contacts list of users and proliferated to such an extent that it caused damage to the operation of millions of computers throughout the world. 5. MyDoom, like Sobig, proliferated through emails. By sending a fake message, often in the form of an alert, Mydoom infected a computer and the same message was sent to all contacts, resulting in an enormous worldwide problem.