The UNC implementation 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 does not include authentication from the server to the client, which allows remote attackers to execute arbitrary code by making crafted data available on a UNC share, as demonstrated by Group Policy data from a spoofed domain controller, aka "Group Policy Remote Code Execution Vulnerability."