A modern RAT A R.A.T. (for Remote Access Tool, also called an R.C.S., for Remote Control System, a backdoor, or a trojan) refers to software that allows an operator to remotely control one or more systems, whether it be a computer, a smartphone, a server or an internet-connected printer. RATs are not always used for offensive operations, for example, you may know TeamViewer, which is often used for remote support and assistance (and by low-tech scammers). In the context of offensive security, a RAT should be as stealthy as possible to avoid detection and is often remotely installed using exploits