Sysinternals Freeware - RootkitRevealer

Sysinternals Freeware - RootkitRevealer: "What is a Rootkit?

The term rootkit is used to describe the mechanisms and techniques whereby malware, including viruses, spyware, and trojans, attempt to hide their presence from spyware blockers, antivirus, and system management utilities. There are several rootkit classifications depending on whether the malware survives reboot and whether it executes in user mode or kernel mode."