Earlier this month, I posted an update on the November Patch Tuesday security releases from Microsoft, which you can read about here. In that posting, I detailed that although it was a massive update of sixteen patches, two updates were not ready for release. The first of those two patches, MS14-068 has now been released by Microsoft and is the fifth patch rated as critical for November by Microsoft.
The Microsoft security update MS14-068 attempts to resolve a privately reported vulnerability in the Kerberos Key Distribution Centre (KDC) authentication system. Once a system has been compromised through this vulnerability, an attacker could impersonate any account (including domain administrator) with the potential to create, edit, or delete any system account. In addition to the severity of this potential security issue, Microsoft has reported limited targeted attacks of this particular vulnerability.
This patch updates a significant number of operating system files (DLL’s) and also updates the SChannel library which was included in the update MS14-066
This is definitely a "patch now” Microsoft update
Chris Goettl has a great blog on these issues which you can find here:
Additional references for this Microsoft update can be found at the Knowledge base article KB2992611