Summary

Melissa.W is a version of one of the most widespread viruses in history, Melissa.A. The original Melissa spread around the world as an e-mail chain letter in March 1999.

Additional Details

After January 17th, 2001, F-Secure started receiving reports about a new version of Melissa, this time spreading in a file called Anniv.doc.

This version was named Melissa.W. It's not really a new version of the virus; the format of the infected file has changed. The file Anniv.doc is in Microsoft Word 2001 for Macintosh format. This is problematic, as several antivirus programs are still unable to handle this new file format, but the file and the virus is fully functional under both Macintosh and Windows versions of Microsoft Office.

By January 19th, we had received dozens of infection reports from various parts of the world, with the rate of infections increasing. It seems that this virus might become very widespread rapidly.

The only functional difference between Melissa.A and Melissa.W is that the W variant does not lower the macro security settings in Word 2000.

For full details on the Melissa virus, see the description of Melissa.A at http://www.F-Secure.com/v-descs/melissa.shtml

The worm sends e-mail to addresses found from Microsoft Outlook address book.

The e-mails look like this:

From: (name of infected user) Subject: Important Message From (name of infected user) To: (50 names from address book)
Here is that document you asked for ... don't show anyone else ;-)
Attachment: Anniv.doc (the infected active document)
Do notice that Melissa.W can arrive in any document - the attachment does not necessarily have to be named Anniv.doc. The infected attachments might also contain confidential data from the infected computers.

E-mail worms such as Melissa spread effectively, as users are likely to open a e-mails coming from someone they know.

You don't need to have Microsoft Outlook to receive the virus in e-mail. However, the virus will not spread further from your machine via e-mail unless you have Outlook installed.

Melissa will not work under Word 95 and will not spread further under Outlook Express. It can infect Windows 95, 98, Me, NT, 2000 and Macintosh users.

F-Secure Anti-Virus is capable of detecting Melissa.W even though it spreads inside a Word 2001 for Macintosh document.

Download your updates from here: http://www.f-secure.com/download-purchase/updates.shtml

[Analysis: Katrin Tocheva, Mikko Hypponen and Sami Rautiainen, F-Secure]