A RAT's installation mechanism is usually attached to a legitimate program. RATs are commonly hidden within games or other small programs, as well as in email attachments that users download. Imposters are able to customize RAT features, such as when and where to launch the Trojan. Intruders eventually trigger the server program on the victim's computer. Then, the RAT runs invisibly on the victim's computer and allows the intruder to gain remote access and control of the infected computer.