A Trojan Horse, or simply Trojan, is a malware that presents itself as a useful program but actually does extensive damage by allowing unauthorized access to your computer, wreak havoc on your system, and may even erase your hard disk.
How Trojans Work
Trojans are spread over the Internet through a number of ways, such as through emails, chat programs, and the download of files that may actually contain beneficial material but also include concealed Trojans. Once these files are opened or executed, the malicious program is installed on your computer. Thus, the victim of a Trojan attack has to install the server end of the program in order for it to work. And once installed, the program will run automatically every time your computer is turned on.
Also, many Trojans also incorporate a worm that accesses your email addresses and sends them a message with the Trojan attachment. Malicious hackers, also called crackers, can create a network of zombie computers through this worm. This network of zombie computers, also called botnets, can then be used to spread even more Trojans throughout the network. They are called zombies because their users rarely know the computers are infected.
As soon as an infected computer, which is the server in this application, is powered up, Trojan sends it IP Address to the attacker, or client. This allows the attacker to communicate with the infected computer and access its files or even erase them.
Methods of Prevention
The best way to prevent the entrance of a Trojan Horse and keep it from infecting your computer is to avoid opening email attachments or files that have been sent by unknown senders. Deleting them should deal with the problem. Also, be wary of downloading materials from sites that you are not familiar with. If a download appears too good to be true, it probably is.
Yet, not all files are guaranteed to be virus-free. It is therefore important to install and regularly update an antivirus or an anti-spyware program to shield your computer from malicious programs.
For more information on Trojan Horse Virus read: