Trojan horse
A destructive program masquerading as a benign application. Unlike viruses, Trojan horses do not replicate themselves but they can be just as destructive. One of the most insidious types of Trojan horse is a program that claims to rid a computer of viruses but instead introduces viruses onto the computer. Some Trojan horses are able to be controlled remotely and are referred to as Remote Controlled Trojan Horses (RCTHs).