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JS/The_Fly is a worm that mass-mails itself. It is written with JavaScript and it is spread in a compiled HTML file. These files use extension "CHM".


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


When the worm is executed, it first copies itself to Windows directory as "THE_FLY.CHM" and to Windows system directory as "DXGFXB3D.DLL".

Next t opens a window with a picture and the following message:

If you ride a motorcycle, close your mouth.

After the window has been shown the worm drops an JavaScript file, "MSJSVM.JS", to the Windows system directory. The it modifies the Windows registry in a such way that this script will be executed on each system startup.

Then JS/The_Fly will use Outlook to mass-mail itself to all recipients in all address books. The message it sends looks as follows:


Funny thing

 Body: > If you ride a motorcycle, close your mounth. :)

 Attachment: THE_FLY.CHM

This worm removes sent mail from the user's "Sent items" folder to hide itself.

When the system is restarted, the "MSJSVM.JS" script executes. This script will alter mIRC and Pirch98 IRC clients settings in a such way, that the worm will be sent each time when the user joins a IRC chat channel. It replaces the "script.ini" from the mIRC installation directory and "events.ini" from Pirch98 installation directory.

Finally, the number of minutes is equal to 30, JS/The_Fly shows a message box with the following text:

//MIRC/OUTLOOK/PIRCH.CommonSense by Zulu

 if (CommonSense == true) { God = false; Religion = false;


 else { God = true; Religion = true;



This variant is the same as The_Fly.A, except the virus code has been encrypted.