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Virus Encyclopedia

Welcome to the Virus Encyclopedia of Panda Security.


Threat LevelModerate threatDamageHighDistributionNot widespread
Common name:Opaserv.O
Technical name:W32/Opaserv.O
Threat level:Low

Opaserv.O activates on or after December 24 2002, deleting the contents of the infected computer’s CMOS (BIOS or Setup information) and hard disk.

Affected platforms:

Windows ME/98/95

Detection updated on:Oct. 29, 2007
Proactive protection:
Yes, using TruPrevent Technologies
Repair utility:Panda QuickRemover

Brief Description 


Opaserv.O is a worm that activates if the date is December 24 2002 or later.

The effects of Opaserv.O are very dangerous as it deletes the infected computer's BIOS information (CMOS memory) and the contents of the hard disk.

Opaserv.O spreads across networks and shared resources. It affects computers or resources (for example, communications ports) that are connected to other infected computers.

Opaserv.O exploits a vulnerability in Windows Me/98/95.

Visible Symptoms 


One it has infeted the computer, Opaserv.O restarts the infected machine and displays a message in an MS-DOS window.

This message simulates a warning about the version of the Windows operating system installed on the affected computer:

Illegal Microsoft Windows license detected!
You are in violation of the Digital Millennium Copyright Act
Your unauthorized license has been revoked
For more information, please call us at:
If you are outside the USA, please look up the correct contact information on our website, at:
Business Software Alliance
Promoting a safe & legal online world

After displaying this message, Opaserv.O deletes the content of the computer's CMOS (BIOS) and hard disk.