Seriously. This in from Neowin (via Dell SecureWorks):
“Dell SecureWorks Counter Threat Unit(TM) (CTU) researchers discovered malware that bypasses authentication on Active Directory (AD) systems that implement single-factor (password only) authentication. Threat actors can use a password of their choosing to authenticate as any user. This malware was given the name "Skeleton Key." – Dell
This installs as a memory patch of Active Directory and since it’s not logged and completely silent, it’s very difficult to detect. It also generates no network traffic.
The only good news?
“in its current form, the malware does not survive a system reboot. Also, the fact that it requires administrator rights to install limits the attack surface, making a disgruntled sysadmin one of the largest threat vectors. In addition, according to the researchers, the malware is rendered useless if an organization requires two-factor authentication to connect to servers, VPN, email and the like.” – neowin
Sources:
http://www.neowin.net/news/new-skeleton-key-malware-allows-bypassing-of-passwords
http://www.secureworks.com/cyber-threat-intelligence/threats/skeleton-key-malware-analysis/