Analysis by: Mark Joseph Manahan
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 298,000 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 05 Jun 2012

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %Program Files%\Common Files\AdvBHO.dll

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

Autostart Technique

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

HKEY_CLASSES_ROOT\CLSID\{2ED2390A-E6F6-F895-FE75-013E2D97184A}\
InprocServer32
{Default} = "%Program Files%\Common Files\AdvBHO.dll"

HKEY_CLASSES_ROOT\CLSID\{ABF94C77-38BF-0744-BC6B-11809F22D88D}\
InprocServer32
{Default} = "%Program Files%\Common Files\AdvBHO.dll"

It adds the following registry keys to install itself as a Browser Helper Object (BHO):

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{2ED2390A-E6F6-F895-FE75-013E2D97184A}

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\AdvBHO.AdvBHO

HKEY_CLASSES_ROOT\AdvMimeFilter.AdvMimeFilter

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{2ED2390A-E6F6-F895-FE75-013E2D97184A}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{ABF94C77-38BF-0744-BC6B-11809F22D88D}

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.188.03
FIRST VSAPI PATTERN DATE: 13 Jun 2012
VSAPI OPR PATTERN File: 9.189.00
VSAPI OPR PATTERN Date: 13 Jun 2012

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 key

[ 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CLASSES_ROOT\CLSID\
    • {2ED2390A-E6F6-F895-FE75-013E2D97184A}
  • In HKEY_CLASSES_ROOT\CLSID\
    • {ABF94C77-38BF-0744-BC6B-11809F22D88D}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\
    • {2ED2390A-E6F6-F895-FE75-013E2D97184A}
  • In HKEY_CLASSES_ROOT\
    • AdvBHO.AdvBHO
  • In HKEY_CLASSES_ROOT\
    • AdvMimeFilter.AdvMimeFilter
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\
    • {2ED2390A-E6F6-F895-FE75-013E2D97184A}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\
    • {ABF94C77-38BF-0744-BC6B-11809F22D88D}

Step 4

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.
  • %Program Files%\Common Files\AdvBHO.dll

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_BHO.CHA. 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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