Troj_Sirefef.kby is a variety of Sirefef malware. It never walks alone as the threat belongs to a multi-component infection.
Subject to detection approach applied it is reported as a single trojan or dissolves in the complex malware it belongs to.
Removal of Troj_Sirefef.kby is associated with one vividly discussed obstacle that prevents its detectors from killing the rogue, namely that it is installed onto the location containing system installer files. Indeed, rash decisions and actions are not appropriate for threats lurking there, since a slightest error might result in Windows crash.
Get rid of Troj_Sirefef.kby gently cleaning the directory it is resident to, be it white-listed area, temporary folder or any other part of your computer memory – rely on verified free scanner to be installed through this secure link. Needless to say, the trojan’s allies will be recognized, located and wiped off at once.