The Cleaner was created in response to the Back Orifice trojan. It was claimed by the authors of this trojan that it was unstoppable and undetectable. We took this as a challenge and devised a way to detect and remove it. Thus the very first anti-malware application was created. In the process of doing this we expanded our goals and added more common malware of the day. It was quickly realized that our method could be used to generically detect all known malware. Our process remains at the core of The Cleaner today along with several added technologies.