Backdoor
The term backdoor often refers to backdoor programs - applications that open computers for access by remote systems. These programs typically respond to specially-built client programs, but can be designed to respond to legitimate messaging applications. Many backdoor programs actually make use of the IRC backbone, receiving commands from common IRC chat clients via the IRC network.
Backdoor programs (detected by Trend Micro antivirus as BKDR_malwarename) typically cannot propagate on their own.
