This video shows a method by which a user can use a Linux distro called BackTrack to gain system access to Windows Vista without logging into Windows or knowing the username or password for any accounts. To accomplish this, the user renames cmd.exe to Utilman.exe, this is the program that brings up the Accessibility options for users without sight or with limited vision. The attack takes advantage of the fact that the Utility Manager can be invoked before the user logs into the system. The user gains System access, which is a level higher than Administrator. The person who discovered this security hole claims that XP, 2000, 2003 and NT are not vulnerable to it; only Windows Vista is.

http://www.offensive-security.com/movies/vistahack/vistahack.html