PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives via removable drives.

It drops copies of itself in all removable and physical drives found in the system. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size: 1,793,672 bytes
File Type: VBS
Memory Resident: Yes
Initial Samples Received Date: 02 Feb 2012

Arrival Details

This worm arrives via removable drives.

Installation

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

  • %System%\Thumbs.vbs
  • %Windows%\Thumbs.vbs

(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.. %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_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
avctrl32 = "wscript.exe %System%\Thumbs.vbs"

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\vbsfile\DefaultIcon
(default) = "%SystemRoot%\System32\shell32.dll,-154"

HKEY_CLASSES_ROOT\VBSFile
(default) = "Data Base File"

Propagation

This worm drops copies of itself in all removable and physical drives found in the system.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[AUTORUN]
open=wscript.exe Thumbs.vbs
icon=0
shell\install = &Install
shell\install\command = wscript.exe Thumbs.vbs
shell\uninstall = &UnInstall
shell\uninstall\command = wscript.exe Thumbs.vbs
shell\readme = &Read Me
shell\readme\command = wscript.exe Thumbs.vbs
shell\help = &Help
shell\help\command = wscript.exe Thumbs.vbs
shell\Open = &Open
shell\Open\command = wscript.exe Thumbs.vbs
shell\Open\Default=1
shell\Run = &Run
shell\Run\command = wscript.exe Thumbs.vbs
shell\Run\Default=1
shell\explore=Explorer
shell\explore\Command=Explorer.exe

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.748.08
FIRST VSAPI PATTERN DATE: 02 Feb 2012
VSAPI OPR PATTERN File: 8.749.00
VSAPI OPR PATTERN Date: 02 Feb 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 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\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • avctrl32 = "wscript.exe %System%\Thumbs.vbs"
  • In HKEY_CLASSES_ROOT\vbsfile\DefaultIcon
    • (default) = "%SystemRoot%\System32\shell32.dll,-154"
  • In HKEY_CLASSES_ROOT\VBSFile
    • (default) = "Data Base File"

Step 4

Search and delete AUTORUN.INF files created by VBS_AUTOWORM.JW that contain these strings

[ Learn More ]
[AUTORUN]
open=wscript.exe Thumbs.vbs
icon=0
shell\install = &Install
shell\install\command = wscript.exe Thumbs.vbs
shell\uninstall = &UnInstall
shell\uninstall\command = wscript.exe Thumbs.vbs
shell\readme = &Read Me
shell\readme\command = wscript.exe Thumbs.vbs
shell\help = &Help
shell\help\command = wscript.exe Thumbs.vbs
shell\Open = &Open
shell\Open\command = wscript.exe Thumbs.vbs
shell\Open\Default=1
shell\Run = &Run
shell\Run\command = wscript.exe Thumbs.vbs
shell\Run\Default=1
shell\explore=Explorer
shell\explore\Command=Explorer.exe

Step 5

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