JS/Coolsite.A@mm is a mass mailer written in Java Script. It uses a vulnerability in Internet Explorer to execute itself directly from an infected web page.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
Further information about this vulnerability, including a fix, is available from Microsoft:https://www.microsoft.com/technet/security/bulletin/MS00-075.asp
When the worm executes, it first changes the Internet Explorer start page to an adult web site. After that the worm reads emails from the Sent mail folder and sends the following message to each of them:
Subject: Hi!! Body: Hi. I found cool site! http://celebxx.cjb.net It's relly cool!
After sending, the worm deletes messages to hide itself from the end user.
The worm is not written to send out any attachments but to activate from a web page. Because of the method that it uses, it might send out with itself attachments which were originally included in the messages in the Sent mail folder.
F-Secure Anti-Virus detect this worm with the current updates.