New Screen Lock Ransomware poses as Microsoft License Manager (Sept 9, 2011)

The Sonicwall UTM research team received reports of a new Ransom Malware in the wild. Malware of this nature holds a compromised machine hostage until payment is made. This software pretends to come from Microsoft and claims that the license used on the compromised system is not authentic. As a result the user is encouraged to buy a “license” from the creators of the Trojan. The user is forced to do this from another machine as the desktop is locked.

Upon execution, the Trojan will immediately reboot the system. On reboot, the following screen will be displayed:

There is no conventional way of exiting the screen other than to follow the malicious instructions for obtaining a license from www.buylicens.com for 50 Euros.

The following screenshot is from www.buylicens.com and has been partially translated to from german to english:

The Trojan performs the following DNS query:

• lic{removed}.cz.cc (This site is currently down)

The Trojan creates the following files on the filesystem:

• C:Documents and Settings{USER}Start MenuProgramsStartupmsvcs.exe [Detected as GAV: Ransom.A_2 (Trojan)]

(This is a copy of the original executable that was run)

The Trojan creates the following keys in the Windows registry:

Enable startup:

• HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun “C:Documents and Settings{USER}Application Data9A52917-B4FC-4f02-AE3B-BF55D9351F4Amsvcs.exe”
• HKEY_CURRENT_USERSoftwareMicrosoftWindows NTCurrentVersionWinLogon “C:WINDOWSsystem32userinit.exe,C:Documents and Settings{USER}Application Data9A52917-B4FC-4f02-AE3B-BF55D9351F4Amsvcs.exe”

The Trojan injects code into a Firefox browser process. If Firefox is not present on the system it falls back to using Internet Explorer. It causes the following network conversation with a remote host:

During analysis it was discovered that the Trojan exectuble file contains the unlock key (QRT5T 5FJQE 53BGX T9HHJ W53YT) in plain text. This key appears to remove the Trojan:

SonicWALL Gateway AntiVirus provides protection against this threat via the following signature:

• GAV: Ransom.A_2 (Trojan)

Security News

The SonicWall Capture Labs Threat Research Team gathers, analyzes and vets cross-vector threat information from the SonicWall Capture Threat network, consisting of global devices and resources, including more than 1 million security sensors in nearly 200 countries and territories. The research team identifies, analyzes, and mitigates critical vulnerabilities and malware daily through in-depth research, which drives protection for all SonicWall customers. In addition to safeguarding networks globally, the research team supports the larger threat intelligence community by releasing weekly deep technical analyses of the most critical threats to small businesses, providing critical knowledge that defenders need to protect their networks.