/Library/Apple/System/Library/CoreServices/MRT.app/Contents/MacOS/mrt-helper MRT, standing for Malware Removal Tool, is a malware protection technology that automatically removes harmful software from your Mac based on the information updated by Apple. It examines your Mac for malware when restarting and logging in.
The binary is a part of mrt-helper application.
/System/Library/CoreServices/mrt-helper