Threat Description

Worm: W32/Downaduprun.A


Category: Malware
Type: Worm
Platform: W32
Aliases: Worm:W32/downaduprun, downaduprun, Worm:W32/Downaduprun.A


Worm:W32/Downaduprun.A is Generic Detection of the malicious autorun files created by Worm:W32/Downadup, which exploit the Windows Autorun functionality to spread the worm.


Automatic action

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

More scanning & removal options

More information on scanning or removal options is available in the documentation for your F-Secure security product on the Downloads section of our Home - Global site.

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

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

Typical Autorun.inf files are very small in size. The Downadup worm inflates the size of its autorun.inf in an attempt to avoid detection by antivirus signature scanners. Binary characters are used to inflate the file size. These binary characters are ignored by the Windows operating system.


On execution of the file, Windows runs the bloated file and finds the following command buried in the garbage text:

  • Open=RUNDLL32.EXE .\RECYCLER\jwgvsq.vmx

This command executes a DLL called jwgvsq.vmx from a hidden folder on the removable drive containing the malicious autorun.inf.


This malware is discussed in the following Labs Weblog post:

Description Created: 2009-01-20 10:51:34.0

Description Last Modified: 2010-09-29 09:53:51.0


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