Analysis by: Christopher Daniel So
ALIASES:

Worm:Win32/Hamweq.DD (Microsoft), W32.Pilleuz (Symantec), Trojan.Win32.Menti.cpb (Kaspersky), Worm.Win32.Hamweq (Ikarus)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan may be downloaded from remote sites by other malware.

  TECHNICAL DETAILS

File Size: 20,992 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 10 Feb 2011

Arrival Details

This Trojan may be downloaded from remote site(s) by the following malware:

  • WORM_PALEVO.SMS
  • WORM_RIMECUD.ZB

It may be downloaded from the following remote sites:

  • http://two.{BLOCKED}raoi.com/bnet.exe
  • http://two.{BLOCKED}raoi.com/serv8.exe
  • http://two.{BLOCKED}raoi.com/dq.exe

Installation

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

  • %System Root%\RECYCLER\{random SID}\vsbntlo.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It drops the following files:

  • %System Root%\RECYCLER\{random SID}\Desktop.ini - nonmalicious file

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
12CFG214-K641-12SF-N85P = "%System Root%\RECYCLER\{random SID}\vsbntlo.exe"

NOTES:
It drops the file %System Root%\RECYCLER\{random SID}\Desktop.ini so that the folder, %System Root%\RECYCLER\{random SID}, will be treated by the computer as the default Recycle Bin folder.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.856.05
FIRST VSAPI PATTERN DATE: 24 Feb 2011
VSAPI OPR PATTERN File: 7.857.00
VSAPI OPR PATTERN Date: 25 Feb 2011

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Remove the malware/grayware file dropped/downloaded by TROJ_FAKEAV.SM8

    WORM_PALEVO.SMS
    WORM_RIMECUD.ZB

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • 12CFG214-K641-12SF-N85P=%System Root%\RECYCLER\{random SID}\vsbntlo.exe

Step 5

Search and delete this file

[ Learn More ]
There may be some 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. %System Root%\RECYCLER\{random SID}\Desktop.ini

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_FAKEAV.SM8. 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.