Analysis by: Abraham Latimer Camba
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size: 40,960 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 27 Sep 2011

Arrival Details

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

  • %System%:msfullcomen.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It adds the following processes:

  • iexplore.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{3ghj94C0-7BF8-95A0-9892-DHE31j9F2AF8}
StubPath = "%System%:msfullcomen.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{3ghj94C0-7BF8-95A0-9892-DHE31j9F2AF8}

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
\Recent File List

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
\Settings

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}i.{BLOCKED}s.com

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.458.09
FIRST VSAPI PATTERN DATE: 27 Sep 2011
VSAPI OPR PATTERN File: 8.459.00
VSAPI OPR PATTERN Date: 28 Sep 2011

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.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {3ghj94C0-7BF8-95A0-9892-DHE31j9F2AF8}
  • In HKEY_CURRENT_USER\Software
    • Local AppWizard-Generated Applications

Step 4

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


Did this description help? Tell us how we did.