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Trojan Horse Programs

Trojan Horse - Definition Provided by Webopedia

A destructive program that masquerades as a benign application. One of the most insidious types of Trojan horse is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer.

The term comes from the a Greek story of the Trojan War, in which the Greeks give a giant wooden horse to their foes, the Trojans, ostensibly as a peace offering. But after the Trojans drag the horse inside their city walls, Greek soldiers sneak out of the horse's hollow belly and open the city gates, allowing their compatriots to pour in and capture Troy.

Trojan Horse Programs - What are they?

Trojan horse programs typically disguise themselves as innocent looking files that appear to be safe to click on. They work somewhat in the manner of a classic booby trap; once you open the box, it explodes in your face. The most irritating aspect of a Trojan horse virus is the fact that the users themselves actually take a hand in infecting their own computer.

One popular type of Trojan takes the form of an email virus. A Trojan Horse program will come across as an email attachment from a trusted source. Unfortunately, the recipient is unaware that the trusted source's computer is already infected, and it is the virus that is sending copies of itself, not the user on the other end. When it installs itself on the new computer, one of the first things that it does is make a copy of the email address book and then start sending out copies of itself to everyone on that list. Of course, the email appears to come from that user, who would be trusted bt=y the next victim. These types of email Trojans are even more destructive to the servers that contain your email mailbox than they are to your computer. What happens is that so many copies of itself are sent back and forth via email that it fills up all of the space on an email server, causing it to crash. Once that happens, no one can send or receive email.

What do Trojan's do?

Trojans can cause a wide variety of problems depending on the agenda and creativity of their creators. One of the more popular functions of a Trojan is to act as a key logger. A key logger is a small program that installs on your computer, runs as some non-intrusive name, and records everything that you type into your keyboard and sends it to another location. This can be email, bank account numbers, or even passwords. Sometimes, this can be used to benefit the good guys - The FBI uses Trojans on specific computers, to help take down major criminals. An example of this is mentioned on our Virus Overview page.

The best way to detect and remove Trojans is through a good antivirus program. There are many programs out there, ranging in price, but the two most popular software packages are Norton Antivirus and McAfee Virus Scan.

To learn more about antivirus programs, go to our antivirus page.

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This page was designed as a project for LIS5362, Design and Production of Network Multimedia, a class at the Florida State University School of Information Studies. Copyright 2004, All Rights Reserved. Last Updated: Nov 2004.