TROJ_INJECT.AUH

October 08, 2012
 Analysis by: Erika Bianca Mendoza
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size:

47,616 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 Apr 2011

Payload:

Connects to URLs/Ips, Drops files

Arrival Details

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following files:

  • %UserProfile%\g23h5.dll - detected by Trend Micro as BKDR_AGENT.AOU
  • %UserProfile%\mslog.dat - non malicious

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wmi
Start = 2

(Note: The default value data of the said registry entry is 3.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wmi
Type = dword:00000110

(Note: The default value data of the said registry entry is dword:00000020.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wmi\Parameters
ServiceDll = %UserProfile%\g23h5.dll

(Note: The default value data of the said registry entry is %SystemRoot%\System32\advapi32.dll.)

NOTES:

The dropped DLL component is injected into SVCHOST.EXE to remain memory resident.

It connects to {BLOCKED}.{BLOCKED}.17.210 and sends basic system information.

  SOLUTION

Minimum Scan Engine:

8.900

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

Remove malware files dropped/downloaded by TROJ_INJECT.AUH

    BKDR_AGENT.AOU

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Restore this modified 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\SYSTEM\CurrentControlSet\Services\Wmi
    • From: Start = 2
      To: Start = 3
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Wmi
    • From: Type = dword:00000110
      To: Type = dword:00000020
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Wmi\Parameters
    • From: ServiceDll = %UserProfile%\g23h5.dll
      To: ServiceDll = %SystemRoot%\System32\advapi32.dll

Step 5

Search and delete this file

[ 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. %UserProfile%\mslog.dat

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_INJECT.AUH. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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