A trojan horse is a program or utility that appears to be something useful or safe, but in reality is performing background tasks such as giving access to your computer or sending personal information to other computers. Trojan horses are one of the most common methods a criminal uses to infect your computer and collect personal information from your computer. Below are some basic examples of how your computer could become infected with a Trojan horse.
A site offers a free download to a program or game that normally costs money. Downloading the pirated version of a program or game allows you to illegally use or play it, however, during the install it also installed a Trojan horse onto the computer.
A popular screen saver website has become infected or uploaded infected screen savers. Downloading the screen saver to your computer also installs a Trojan horse onto the computer.
You receive an e-mail that appears to be from a friend asking you to view this fantastic new program or look at a file. Opening the file infects your computer with a Trojan horse.
A friends Facebook account is hacked and has sent out personalized messages telling all their friends to see this exciting new video. Opening the video requests a download that has a hidden Trojan horse that infects your computer.