The SAM and LSAD protocol implementations in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, and Windows 10 Gold and 1511 do not properly establish an RPC channel, which allows man-in-the-middle attackers to perform protocol-downgrade attacks and impersonate users by modifying the client-server data stream, aka "Windows SAM and LSAD Downgrade Vulnerability" or "BADLOCK."
https://www.samba.org/samba/security/CVE-2016-2118.html
https://www.kb.cert.org/vuls/id/813296
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-047
https://bto.bluecoat.com/security-advisory/sa122