What is a Computer Trojan?

Introduction

The term Computer Trojan has often been used interchangably with the term Computer Virus, but in reality has slightly different characteristics. Trojan computer infections are named after the Ancient Trojans who believed the giant horse left behind by the Greeks was a peace offering after years of war. They happily accepted the free gift and brought it inside the walls of their city. Greek invaders hiding inside the horse waited until night, slipped out and opened the front door so the rest of the invaders could come inside the city and take over. This is essentially the way a computer trojan works, you think you are getting something for free (music, smilies, screensaver etc.) and you end up with a bunch of nasty programs on your computer.

Technical Information

The Trojan horse is basically a malicious program accompanied by spyware which you get through email attachment, a messenger program, or from an internet download. Trojans sometimes masquerade as a free program you would like. Once you accept the Trojan into your computer, it will perform a basic installation of itself. Typically, trojans tend to do the following:

• Aid in hijacking your web-browser. This means that when you want to go to a particular homepage such as Google or MSN, you end up somewhere else.
• Record your keystrokes and transmit it to the attacker. This gives them access to any password protected accounts you have set up, including banking and other sensitive data.
• Do malicious functions such as rebooting your PC or deleting something.
• Allow the attacker access to your PC to run other code.
• Become a spam relay - sending vast amounts of spam to everyone else.

The main difference between a computer virus and a computer trojan is that a Trojan does not try to replicate itself.

Method of Infection

Infection usually occurs with the consent of the victim, giving permission to download and open a program when visiting a website. It can also be transmitted via email attachment or chat program.

Detection

Most anti-virus programs and some anti-spyware programs will detect most known Trojans. If you believe you have a computer Trojan that is not being detected, you can have a technician verify and remove the trojan from your system.

Summary

A trojan horse infection creates a backdoor to your PC allowing the attacker to do whatever they want to your computer. They can record your keystrokes, spy on you, read your emails and so on. This happens because you have installed or downloaded a program you shouldn't have. All trojans are removable. The experts at support.com can remove a computer trojan if you're infected.