trojan horse

Trojan Horse-A trojan horse, or trojan, as the name implies, secretly carries often-damaging software in the guise of an innocuous program, often as an email attachment. The file name itself is normally misleading to entice you to open it. A program that neither replicates nor copies itself, but performs some illicit activity when it is run. It stays in the computer doing its damage or allows somebody from a remote site to take control of the computer.