Trojan Horse

Monday, October 15th, 2007

What is a Trojan Horse?

Trojan Horses are a type of computer program that appear to perform a certain function, but actually perform other, often malicious, actions. They differ from traditional viruses because they do not have the means to automatically replicate. Trojan horses can be classified based on how they breach and damage systems. They are primarily used for unauthorized remote access, mass-mailing spam, data destruction, file transfer, toll-line dialing, and denial-of-service attacks.

Today, Trojans are notorious for implementing backdoor programs that allow attackers unauthorized access to victims’ systems. Unlike traditional computer viruses and other types of malware, they are designed with the intention of exploiting infected systems, rather than replicating themselves or disabling a system completely. However, in order for an attacker to gain access to a system, the victim must run an executable server file. These are usually spread through email attachments, peer-to-peer file sharing systems, and Internet downloads. These remote-access servers arrive unbeknownst to the end-user, disguised as important, useful, or desirable files or documents. When executed, these server programs open backdoors that allow attackers to remotely access and control the infected system.

The Code Red virus of 2001 provides a frightening example of the powerful combination of worms and Trojans. Code Red contaminated tens of thousands of computers and caused $2 billion in damages. After propagating itself using the techniques of a worm, Code Red attempted to use the coordinated power of infected machines to launch a “distributed denial of service” attack against www.whitehouse.gov at predetermined date. Thanks to the efforts of virus hunters and technology companies, the viruses code was deciphered and the aggression against the Head of State’s website was unsuccessful.

Protection From Trojan Horses

The majority of Trojans are spread online through network services including email, web sites, file sharing systems, and instant messages. Therefore, any computer connected to the Internet runs the risk of being infected with a Trojan Horse. Avoiding opening all executable (.exe) files would be a sure fire way to avoid being infected with a Trojan Horse. Unfortunately, executable files are essential to run programs and most computer users cannot simply avoid all .exe files.

For protection from Trojans and other malware, any potentially dangerous executable file should be scanned with anti virus software. As their name indicates, Trojan Horses can be sneaky and users oftentimes download a malicious Trojan without even realizing. When this happens, anti virus software can detect and remove these Trojans that attempt to launch viruses, worms and other malware on an unsuspetcing user’s computer. Top anti virus solutions include: McAfee Software, Norton Software, Computer Associates, and AVG.