WORM_VB.WMG

April 08, 2011
 Analysis by: Kathleen Notario
 ALIASES:

W32.SillyFDC (Symantec); Worm:Win32/VB.WJ (Microsoft); Worm.Win32.VB.bms (Kaspersky); W32/Autorun.worm.c (Mcafee); W32/VB-FCM (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives

This worm arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It adds registry entries to enable its automatic execution at every system startup.

  TECHNICAL DETAILS

File Size:

135,168 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Apr 2011

Payload:

Terminates processes

Arrival Details

This worm arrives via removable drives.

It 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 worm drops the following copies of itself into the affected system:

  • %Windows%\{random filename}.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
(default) = "%Windows%\{random filename}.exe"

Other System Modifications

This worm adds the following registry entries:

HKEY_CLASSES_ROOT\exefile
NeverShowExt =

It modifies the following registry entries:

HKEY_CLASSES_ROOT\exefile
(default) = "File Folder"

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

HKEY_CLASSES_ROOT\exefile
TileInfo = "prop:"

(Note: The default value data of the said registry entry is prop:FileDescription;Company;FileVersion.)

HKEY_CLASSES_ROOT\exefile
InfoTip = "prop:"

(Note: The default value data of the said registry entry is prop:FileDescription;Company;FileVersion;Create;Size.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = "1"

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

(Note: The default value data of the said registry entry is 1.)

Process Termination

This worm terminates the following processes if found running in the affected system's memory:

  • cmd.exe

Other Details

This worm does the following:

  • Searches for folders in the following locations then drops copies of itself as {folder name}.EXE:
    • physical drives
    • removable drives
    • C:\Documents and Settings\All Users\Documents
    • %Desktop%
    • %User Profile%\My Documents
  • However, it does not create a copy of itself if the folder's name is the following: system volume information

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.950.07

FIRST VSAPI PATTERN DATE:

04 Apr 2011

VSAPI OPR PATTERN File:

7.951.00

VSAPI OPR PATTERN Date:

05 Apr 2011

Step 1

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

Step 2

Identify and terminate files detected as WORM_VB.WMG

[ Learn More ]
  1. For Windows 98 and ME users, Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • (default) = "%Windows%\{random filename}.exe"
  • In HKEY_CLASSES_ROOT\exefile
    • NeverShowExt =

Step 5

Scan your computer with your Trend Micro product to delete files detected as MALWARE_FILE

*Note: If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further steps are required. You may opt to simply delete the quarantined files. Please check out this Knowledge Base page for more information.


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