The User Profile Service (aka ProfSvc) in Microsoft Windows Server 2003 SP2 Windows Vista SP2 Windows Server 2008 SP2 and R2 SP1 Windows 7 SP1 Windows 8 Windows 8.1 Windows Server 2012 Gold and R2 and Windows RT Gold and 8.1 allows local users to gain privileges by conducting a junction attack to load another user's UsrClass.dat registry hive aka MSRC ID 20674 or \Microsoft User Profile Service Elevation of Privilege Vulnerability.\