?Internet security is a big thing nowadays, as more and more computers are compromised and controlled by people with malicious intent. Compromised computers are often used to attack other computers and sensitive information from the compromised machines are sent to these thieves who then make use of the stolen data (for example, credit card information) for their own gains. The way computers are compromised and controlled is via the use of what is called backdoor trojans. A trojan is a computer program that is disguised to do something useful but actually has another malicious function. When downloaded by unsuspecting users and installed on computers, these programs create a backdoor which allows the hackers access to the computers, thus giving them control and access to the files on the computers. With such a backdoor in place, the hackers can launch more applications on the compromised computer, retrieve files, install more backdoors as well as use the computer to attack other computers. When the compromised computer is used to attack other computers, the hacker makes it look like that computer is the origin of the attack, thus pinning the blame on someone else and hiding their own tracks. If you suspect that your computer may have been infected by a backdoor trojan, the first thing you should do it to download an updated anti-virus software and perform a full system scan. It must be emphasized that the anti-virus software needs to be up-to-date so as to detect modern malware. Trojan backdoors are especially good at hiding themselves. Once detected and cleaned, it's highly advisable to clean up the Windows registry as well. The Windows registry contains information that the system needs to run properly. Many trojans place information inside the registry to prevent detection and to cause problems. When you use a registry cleaner software to scan the entire registry, it will find errors in the registry and fix them for you automatically. A good registry cleaner will help keep your Windows system in good shape and performing optimally. If you are unsure which registry cleaner to use, you can take a look at these reviews of registry cleaners. You can also read about whether registry cleaners really work.