Classified under the category of trojans, backdoor trojan viruses aren?t as feared as their more popular malware kin ? fast-replicating worms and file-infecting viruses. Trojans are nonetheless dangerous and may prove to be a greater problem, particularly as users could be unaware of their presence in a computer system.

Trojans are distributed in various ways: scanning a network and finding vulnerable computers; creating a website that exploits browser weaknesses and silently install the trojan on visitors; or distributing tons of emails with tempting baits that entice users to download a file, watch a video or simply visit a site. The trojan horse payload may be harmless, but most are computer security nightmares. The most common payloads are designed to make the target PC participate in Distributed Denial-of-Service attacks (DDoS), destroy data, turn the local computer into a trojan server, disable installed security software, download or drop data from other PCs, or enable remote access.

Having backdoors in a PC may result in slower system performance and heightened vulnerabilities to other malware. But the greater danger lies in the ability of the trojan controller to use the computer (in a Botnet) for illegal or criminal activities, such as launching DDoS attacks, identity theft particularly passwords and credit card data used in financial fraud, and spreading more malware. It is therefore important to make sure that your system is free from backdoor trojans viruses.

The first thing users must do is to take extra care to make sure that backdoors do not gain entry. These can be done by updating the computers security system and installing the latest patches that plugs security loopholes. One must also avoid dubious sites and should handle suspicious emails with caution ? remember that it merely takes a site drive-by or opening an email for a trojan to be installed. As the clich