Summary

VBS/Tune is an e-mail worm written in VBScript language that propagates when the receiver double-clicks on the attachment.

Programs written in VBScript operate only under Windows 98 and Windows 2000 (unless Windows Scripting Host has been installed).

Additional Details

VBS/Tune does not work at all under default Windows 95 and Windows NT 4.0 installations. However, it does work under 95 and NT 4 provided that other supporting software (such as Microsoft Internet Explorer v5.x) has been installed.

Tune was found in December 1999. This worm uses similar method to spread like Melissa and Freelink. The mass-mailing part uses Outlook, while mIRC and Pirch are also used to spread the worm.

When Tune is executed, it copies itself to three different directories - Windows, Windows' system and temporary directories. After that it changes the registry in a such way that it will be executed when the system is restarted:

    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ScanRegistry
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\TaskMonitor

Then it copies itself to the root of each fixed and network drive.

The worm uses Outlook application to send itself as an attachment to all recipients in every address book. The e-mail message that VBS/Tune sends contains the following subject and body:

        Subject: Please Read
        Body:    Hey, you really need to check out this attached file
                 I sent you...please check it out as soon as possible.

The worm checks the registry if the mailing has been already done and if yes, then it does not do mass-mail itself again.

VBS/Tune does not remove the sent mail from "Sent Items" folder. On that way the mass-mailing is visible for the user.

The worm also spreads via mIRC and Pirch chat clients. It searchs for "C:\MIRC" and "C:\Pirch98" directories. If Tune founds either one, it will overwite the "script.ini" and "events.ini" respectively.

After that both IRC clients will automatically spread the worm when the user enters IRC chat channels.

[Analysis: Katrin Tocheva & Sami Rautiainen, F-Secure]