ProRat is a Microsoft Windows based backdoor trojan horse, more commonly known as a RAT (Remote Administration Tool). As with other trojan horses it uses a client and server. ProRat opens a port on the computer which allows the client to perform numerous operations on the server (the machine being controlled). ProRat is available in a free version, and a paid version. In the free version, ProRat cannot connect to users over wide area networks (WANs), only over LANs (Local Area Networks). ProRat is known for its server to be almost impossible to remove without up-to-date antivirus software.