A remote administration utility which bypasses normal security mechanisms to secretly control a program, computer or network.
Disinfection & Removal
This backdoor program attempts to connect to a remote IRC server. It also attempts a Denial-of-Service (DoS) exploit on any machines it finds with an open Microsoft-ds (Directory Service) port.
During installation, the following files are created:
- %windir%\system\wmisvr.exe - Copy of the backdoor
- %windir%\system32\drivers\sysdrv32.sys - Detected as Worm.Win32.AutoRun.ezt
While active, the backdoor attempts to connect to a remote IRC server:
The backdoor also iterates the IP address and looks for available systems with an open Microsoft-ds port (specifically, tcp 445). If a vulnerable machine is discovered, the backdoor breaches the targeted machine's Windows Firewall, a form of Denial-of-Service (DoS) exploit similar to the notorious MS04-011 vulnerability.To protect the backdoor, the WMISRV Service is stopped when the debugger program Ollydbg is launched; this protective action makes the debugging process more difficult.
The backdoor edits the Windows Firewall Policy, to allow it to function as an authorized application.
- HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List C:\WINDOWS\system\wmisvr.exe = C:\WINDOWS\system\wmisvr.exe:*:Microsoft Enabled
It also sets two malware launch points as services:
- HKLM\System\CurrentControlSet\Services\WMISRV ImagePath = "C:\WINDOWS\system\wmisvr.exe" DisplayName = WMI Servicer Description = Auto-Syncs Patches and Hotfixes
- HKLM\System\CurrentControlSet\Services\sysdrv32 ImagePath = \??\C:\WINDOWS\system32\drivers\sysdrv32.sys DisplayName = Play Port I/O Driver
The following mutex name is used by wmisvr.exe: