Threat Description

Backdoor:​W32/Agent.ADQB

Details

Aliases: backdoor.win32.agent.adqb
Category: Malware
Type: Backdoor
Platform: W32

Summary



A remote administration utility which bypasses normal security mechanisms to secretly control a program, computer or network.



Removal



Automatic Disinfection

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.



Technical Details



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.

Installation

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

Activity

While active, the backdoor attempts to connect to a remote IRC server:

  • sec.republicofskorea.info:8084/TCP

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.

Registry

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:

  • ScnBx





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