Analysis by: Christopher Daniel So
 Modified 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:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via flashdrives

This worm searches for folders in the removable drives and creates shortcut links as {folder name}.LNK. The attributes of all the folders found on the drive are changed to Hidden.

This worm arrives via removable drives.

It drops copies of itself into all the removable drives connected to an affected 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: 430,080 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 19 Apr 2011
Payload: Drops files, Modifies system registry, Connects to URLs/Ips, Downloads files

Arrival Details

This worm arrives via removable drives.

Installation

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

  • %User Profile%\{random file name}.exe

(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.)

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
{random file name} = "%User Profile%\{random file name}.exe /{random character}"

Other System Modifications

This worm modifies the following registry entries:

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

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

Propagation

This worm drops copies of itself into all the removable drives connected to an affected 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:

{garbage characters}
[autorun]
{garbage characters}
open={random file name}.eXE
{garbage characters}
acTiOn=13918
{garbage characters}
iCoN=MaA.ico
{garbage characters}
useAutopLay=1
{garbage characters}

Other Details

This worm connects to the following possibly malicious URL:

  • {BLOCKED}r.{BLOCKED}et.com:8003

NOTES:
This worm searches for folders in the removable drives and creates shortcut links as {folder name}.LNK. The attributes of all the folders found on the drive are changed to Hidden.

  SOLUTION

Minimum Scan Engine: 8.900

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

Identify and terminate files detected as WORM_VBNA.ABW

[ Learn More ]
  1. 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.
  2. 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 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
    • {random file name}=%User Profile%\{random file name}.exe /{random character}

Step 4

Restore this modified 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\Explorer\Advanced
    • From: ShowSuperHidden=0
      To: ShowSuperHidden=1

Step 5

Search and delete AUTORUN.INF files created by WORM_VBNA.ABW that contain these strings

[ Learn More ]
{garbage characters}
[autorun]
{garbage characters}
open={random file name}.eXE
{garbage characters}
acTiOn=13918
{garbage characters}
iCoN=MaA.ico
{garbage characters}
useAutopLay=1
{garbage characters}

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_VBNA.ABW. 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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