Trojan horse
From ACT Wiki
1. Cyberthreats
A trojan horse is computer software designed to breach the security of a system, while ostensibly performing a useful or innocuous function.
Sometimes abbreviated to 'trojan'.
2.
More generally, any device or strategy involving deception and concealment, designed to attack an opponent.
The term originates from the myth in which soldiers attacking Troy hid inside an innocuous wooden horse, that the defenders then pulled through the gates of their own besieged city.