The term “Trojan Horse” comes from Greek mythology. In today’s technical world a Trojan Horse is defined as a “malicious, security-breaking program that is disguised as something benign”. In the field of computer architecture, “Trojan Horse” can also refer to security loopholes that kernel code to access system files or programs for which it is not authorized.
A Trojan Horse can be a malicious program with harmful code. It is usually hidden in what looks like normal harmless files, such as email messages or instant messages with attachments. Once opened they can spread themselves to other files or through email recipients using the user’s contact list. Unlike Malware, Trojans do not propagate and self-replicate but depend on the end user spreading the file. They can gain control of your system and do substantial damage. Some types of damage that are common with a Trojan Horse is damage to file allocation tables on your hard drive. While most Trojans are not actually considered viruses they can be a real nuisance. They are more popularly known for the ability to install backdoor programs.
If you have been attacked by a Trojan Horse it is recommended that you remove it immediately. Failure to detect and remove Trojans can result in problems for your system. Some of the more common Trojans result in disconnection from the IRC network, allowing others to access your system and private files. It also allows your system to be hijacked and may be used for criminal purposes. Trojan attacks not only pose a serious threat to your system files and security, you may also be, unintentionally, spreading and infecting others unknowingly. Often Trojans are hidden in everyday files that are downloaded. For example; a user downloads a music or movie file, then clicks on the file to open it. A dangerous program is then unleashed that erases your hard drive and/or transmits your private information such as credit card details and passwords to strangers or it may allow that stranger access to your system.
The best form of defence is to be careful downloading files and use only trusted sites and contacts. Users should only open messages or files from trusted sites and contacts. Lastly, it is vitally important to install and keep a virus protection program, such as Norton’s Anti-virus, maintained and up to date.