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WORM_VB.BWX

June 05, 2013
 Analysis by: Sabrina Lei Sioting
 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 by connecting affected removable drives to a system.

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

It opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

Ports:

Random

File Size:

39,424 bytes

File Type:

PE

File Compression:

UPX

Memory Resident:

Yes

Initial Samples Received Date:

03 Mar 2011

Payload:

Drops files, Compromises system security

Arrival Details

This worm arrives by connecting affected removable drives to a system.

Installation

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

  • %Program Files%\WindowsUpdate\WINLOGON.EXE

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

It drops the following files:

  • %Program Files%\WindowsUpdate\time - non-malicious file

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

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\Policies\
Explorer\Run
IMJPMIG8.1 = "%Program Files%\WindowsUpdate\WINLOGON.EXE"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • RECYCLER.EXE

It drops the following copy of itself in all physical and removable drives:

  • System Volume Information{6 spaces}.EXE

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=RECYCLER.exe
shell\open\Command=RECYCLER.exe
shell\open\Default=1

Backdoor Routine

This worm opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.

Other Details

This worm deletes itself after execution.

NOTES:
Trend Micro detects the dropped AUTORUN.INF as MAL_OTORUN1.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.878.05

FIRST VSAPI PATTERN DATE:

06 Mar 2011

Step 1

Identify and terminate files detected as WORM_VB.BWX

[ Learn More ]
  1. 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 2

Remove the malware/grayware file dropped/downloaded by WORM_VB.BWX

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    IMJPMIG8.1 = %Program Files%\WindowsUpdate\WINLOGON.EXE

Step 4

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.
  • %Program Files%\WindowsUpdate\time

Step 5

Search and delete AUTORUN.INF files created by WORM_VB.BWX that contain these strings

[ Learn More ]
[AutoRun]
open=RECYCLER.exe
shell\open\Command=RECYCLER.exe
shell\open\Default=1

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_VB.BWX. 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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