Threat Description



Category: Malware
Type: Virus
Platform: W32
Aliases: Urkel, NWait


This virus infects the Master Boot Records of hard disks and the DOS boot records of diskettes. It spreads only through diskettes.


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

Urkel does not let the original partition table remain in its proper place in the Master Boot Record, as most other MBR viruses do. This causes the hard disk to be inaccesible after a floppy boot, since the operating system cannot find valid partition data in the Master Boot Record - attempts to use the hard disk result in the DOS error message "Invalid drive specification".

When the computer is booted from the hard disk, the virus is executed first, and the hard disk can thereafter be used normally. The virus is not, therefore, easily noticeable, unless the computer is booted from a diskette.

Do not use FDISK /MBR to clean Urkel: you will loose all your data.

Note: When disinfecting Urkel with F-PROT after a floppy boot, use the command F-PROT /HARD /DISINF instead of using F-PROT C:, or just run F-PROT in interactive mode and scan 'Hard disk' with disinfection option on. After disinfection, error message 'No hard disk found' is normal: just reboot after the disinfection is done and you should see your hard drive again.

Urkel virus sometimes displays text 'Urkel' on screen.


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