Win32.Cakl is a backdoor Trojan and they are among the most popular types of spyware on the Internet today. The reason for their popularity is because of their versatility. They can run in the background without you even knowing they are there. Depending on the needs of the attacker, they can log keystrokes, intercept e-mail, take screenshots, steal passwords, and more.

The only way to prevent backdoor Trojans from infecting your computer is by regularly scanning your computer with a high quality anti-virus. You have to be careful though, some backdoor Trojans are sneaky. They will try to pretend to be anti-virus software.