Threat Description

Worm:VBS/AutoRun.B

Details

Aliases: VBS/Autorun.worm.k, Virus.VBS.AutoRun.b, Type_vbs_autorun
Category: Malware
Type: Worm
Platform: VBS

Summary


A standalone malicious program which uses computer or network resources to make complete copies of itself.



Removal


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.



Technical Details


Worm:VBS/AutoRun.B is a worm that spreads by copying itself to local hard drives, network drives, and removable drives. It has no other functionality.

Propagation

The worm contains four files:

  • __.vbs
  • __.reg
  • __.bat
  • autorun.inf

The first file is the worm's Visual Basic Script file.

The autorun.inf file causes the __.vbs file to be executed when an infected drive is accessed with a computer that has autorun enabled on the drive in question.

The script copies all four files to the root of local hard drives, network drives, and removable drives not labeled A:\ or B:\. The four files are also copied under %windir%\system32.

Execution

The _.reg and _.bat files are detected as Trojan.Win32.Zapchast.ee.

If the script isn't being run from the %windir%\system32 location and therefore hasn't yet been installed, it executes the __.bat file.

The batch file (__.bat) installs the worm by creating the following registry entry to execute itself each time the computer is started:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon Userinit = userinit.exe,__.bat

The batch file can make the registry changes by adding the contents of __.reg in to the registry. If the __.bat file was executed by the registry entry, it then runs the script file.

The batch file also sets the file attributes for all four files to hidden, system, read-only and archive.

The worm also tries to alter this registry entry:

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced ShowSuperHidden

This alteration is an attempt to make hidden files invisible in Windows Explorer.





Description Created: 2008-03-10 10:53:28.0

Description Last Modified: 2010-07-01 08:27:43.0


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