This detection rule targets potential bypasses of User Account Control (UAC) on Windows systems, specifically leveraging the SilentCleanup scheduled task. Attackers may alter the environment variable 'windir', directing it to an unauthorized value to exploit this functionality. The SilentCleanup task, located at '%windir%\system32\cleanmgr.exe', is an auto-elevated task that can be manipulated to run processes with elevated privileges without any UAC prompt. By monitoring changes to the 'windir' variable in the registry, this rule helps identify suspicious activities that may indicate an attempted privilege escalation through UAC bypass.