Coolnow is a worm that uses Microsoft Messenger to propagate. It uses a vulnerability to execute its code via Internet Explorer.

The worm spreads a message via MSN messenger that contains a link to an infected web page. Some of the messages looks as follows:

URGENT - Go to Now

ATTeNT!oN - Go to: Now

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Note! There are several links where the worm code is available. We are trying to shut down these pages which are not disabled yet.

When an user clicks on the link in the MSN message, Internet Explorer will open the page and execute the JavaScript code in the page. This is the actual worm.

The worm uses an vulnerability to execute. It goes through the users MSN contact list and sends a message with a link to an infected site to each recipient.

Further information, including a fix for the vulnerability, is available from Microsoft at:

F-Secure Anti-Virus detects the worm with updates released on February 14th, 2002 at 13:15 local time (GMT+2).

For PocketPC users:

This worm does does not affect PocketPC 2002. Internet Explorer version in PocketPC cannot execute the worm code because its JavaScript implementation does not support activation of MSN messenger via a script.