Spams, scams and shams... Trojan Horses

A guide to trojans and ways to avoid them

Author:  Paul Landers

A trojan horse (or trojan) is a program (or set of instructions) that is hidden inside another file or program. Trojans are different to computer viruses and computer worms in that they do not run autonomously. You can read a more detailed article about computer viruses here and about computer worms here. Like viruses and worms, however, trojans are also classed as "malware" and are harmful to your computer.

Trojans are disguised to appear harmless. They are often found in "free goodies" such as screensavers, games, images, desktop utilities, etc. Like the original Trojan Horse, they are designed to be enticing on the outside, yet dangerous once opened (or run). Trojan horses typically trick users into opening them.

There are many different types of trojans with as many varying intentions. Once run, a trojan can cause direct damage to your computer system and files or it can "open" your system to attacks from hackers.

How do you avoid them? In a similar way to avoiding computer worms - ensure your computer system is up-to-date with Security Updates, anti-virus updates and spyware updates. Be aware and cautious of what you download from suspect websites. If an email attachment seems suspicious, don't open it.

We use a software product called Benign to scan our emails and attachments. It works in the background and ensures that all email we recieve are "clean" before we open them. You can find out more about it here.

Additionally, regular maintenance and "cleaning" of your files will help. You can read a more detailed article about maintaining and cleaning your computer here.