What is Trojan horse and how to protect against them?

Trojan horse is an obfuscated malicious software that hides in a legitimate program such as freeware, shareware or a game application that is designed to perform malicious activity.

Trojan horse can either track can open a security back door to your system allowing other users to access it remotely. Some viruses and worms may be also classified as trojans.

Surprisingly, nowadays the majority of Trojan horses are created outside Greece :)