Threat Descriptons



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Worm:VBS/Onthefly, VBSWG


Worm:VBS/Onthefly (also known as VBS/VBSWG) is an encrypted Visual Basic Script worm which spreads itself through mass-mailing via the Microsoft Outlook application.


Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details


On February 12th, 2001 this worm has spread rapidly in all over the world in just a few hours.

The author of the virus ("OnTheFly") has been found. His real-world identity has been found as well and passed on the the officials for further investigation.

Update on 14th of February, 2001:

The outbreak caused by this virus seems to be quiet now. It seems that the virus caused biggest infection in North America on the 12th of February. This seemed to caused largely because of timezone issues; at this time it was late evening or night time in Europe and Asia. When people in Europe woke up on the 13th, most antivirus programs already handled the virus and the media was warning users from not touching Kournikova-themed attachments.

F-Secure estimates that Onthefly-virus infected several hundreds of thousands of computers worldwide, putting this virus into the same category with Melissa virus in 1999 - which was the largest virus case of its time. However, Onthefly was significantly smaller than LoveLetter. Additionally, Onthefly did not do any direct damage.


This worm arrives as an attachment in Outlook message with the following content:

  • Subject: Here you have, ;o)
  • Body: Hi:
  • Check This!
  • Attachment: AnnaKournikova.jpg.vbs

Once a user click on the attached file, the worm will execute. First of all, it adds the following key to the registry:

  • HKEY_CURRENT_USER\Software\OnTheFly = "Worm made with Vbswg 1.50b"

The worm then copies itself to Windows directory using a constant file name "AnnaKournikova.jpg.vbs" and sends itself to allrecipients on all address books. It also adds a marker to the registry, so it will not mass mail again.At January 26th, the worm will open the web browser and connects to an innocent Netherlander web site.

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