Analysis by: adel
 PLATFORM:

Windows 98, ME, NT, 2000, XP, Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This backdoor has received attention from independent media sources and/or other security firms.

To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

This backdoor may arrive bundled with malware packages as a malware component.

It listens on ports. It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 28,672 bytes
File Type: DLL
Memory Resident: No
Initial Samples Received Date: 06 Mar 2010

Arrival Details

This backdoor may arrive bundled with malware packages as a malware component.

Installation

This backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:

  • liuhong-061120

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\R
Arucer = rundll32 %System%\Arucer.dll,Arucer

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\\rundll32.exe = System%\rundll32.exe:*:Enabled:Run a DLL as an App

Backdoor Routine

This backdoor listens on the following port(s):

  • 7777

It executes the following commands from a remote malicious user:

  • Delete file
  • Create file
  • Download and execute files
  • Modify a certain registry entry
  • Retrieve drive information
  • Retrieve directory listing from the affected machine
  • Upload file

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 6.898.11
FIRST VSAPI PATTERN DATE: 06 Mar 2010
VSAPI OPR PATTERN File: 6.899.00
VSAPI OPR PATTERN Date: 06 Mar 2010

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Arucer = rundll32 %System%\Arucer.dll,Arucer
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\rundll32.exe = %System%\rundll32.exe:*:Enabled:Run a DLL as an App

Step 4

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • Arucer.dll


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