What is Trojan horse program?

A type of program that is often confused with viruses is a ‘Trojan horse’ program. This is not a virus, but simply a program (often harmful) that pretends to be something else.

For example, you might download what you think is a new game; but when you run it, it deletes files on your hard drive. Or the third time you start the game, the program E-mails your saved passwords to another person.

Note: Simply downloading a file to your computer won’t activate a virus or Trojan horse; you have to execute the code in the file to trigger it. This could mean running a program file, or opening a Word/Excel document in a program (such as Word or Excel) that can execute any macros in the document.

List of some computer worms

Badtrans   Bagle      Blaster             Brontok
Code Red           Code Red II       Dabber      Doomjuice
Hybris            Hydra      ILOVEYOU      Klez
Mabutu            Melissa      Morris      Mydoom
Netsky   Nimda      Sadmind             Sasser
Sircam   Sober      Sobig              SQL slammer
Swen            Upering       W32/Bolgimo.worm      Welchia
Witty                   Zotob