Virus Detail

Win32/Vobfus Family

Date Published:
4 Feb 2010

Last Updated:
4 Feb 2010

Threat Assessment

Overall Risk:   None
Wild:  Low
Destructiveness:  Medium
Pervasiveness:  Low

Characteristics

Type : Worm

Category : Win32

Also known as:  Worm.Win32.Basun (Kaspersky), W32/VBNA.worm (McAfee), Worm:Win32/Vobfus (Microsoft)

Immediate Protection Info

 
SignatureProductRemoval Instructions
35.1.7039
CA Antivirus 2007
35.1.7039
eTrust Antivirus v7/8*
7.x/7039
eTrust EZ Antivirus 7.x
35.1.7039
Vet 7
 
 
 

Description

Win32/Vobfus is a family of worms that propagates via removable drives and downloads other files from the Internet.

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Method of Infection

When executed, this malware drops and executes it's copy as %Username% or {Random} filename in %Documents and Settings%\%Username%\ folder.

For example:

If Username is "Administrator", then the dropped file will be "C:\Documents and Settings%\Administrator\Administrator.exe", other variants of this malware drops {Random} filename.


It then creates the following Registry entry to be able to execute itslef every start-up.

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
%Username% = "%Documents and Settings%\%Username%\%Username%.exe"

or

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
{Random} = "%Documents and Settings%\%Username%\{Random}.exe"

Other variants of this malware may also drop its copy in the following path.

%RECYCLER%\{Random CLSID}\Dc{Number}.exe

For example:

C:\RECYCLER\S-1-5-21-1275210071-1303643608-682003330-1117\Dc1.exe
C:\RECYCLER\S-1-5-21-1275210071-1303643608-682003330-1117\Dc2.exe
C:\RECYCLER\S-1-5-21-1275210071-1303643608-682003330-1117\Dc3.exe

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Method of Distribution

Via Removable Drives

This malware has the capability to propagate via removable drives such as USB drives. To do this, it drops two copies of itself in the removable drive, one with .EXE file extension and the other with .SCR file extension.

It then drops the autorun.inf file to be able to execute the dropped .EXE file when Autorun is enabled.

It also drops the following Link (.lnk) or Shortcut files in the removable drive, these points to the dropped .SCR file, thus, executing the shortcut files will tend to execute the malware.

New Folder.lnk
Passwords.lnk
Documents.lnk
Pictures.lnk
Music.lnk
Video.lnk

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Payload

Downloads other files

This malware has the capability to download other possible malicious files from the following sites.

ns1.theimageparlour.net
ns2.theimageparlour.net
ns3.theimageparlour.net
ns4.theimageparlour.net

Modifies Registry entry

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
ShowSuperHidden = dword:00000000

Kills Process

Other variants of this malware attempts to kill "taskmgr.exe" process once found running in the system.

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For additional information:

This malware is usually Visual Basic (VB) compiled executable.

 
Analysis by Ricardo Robielos III

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