This is a worm which attempts to use Microsoft Word 97 to send e-mail to everyone at the address book of the current user. However, it will no infect any Word documents and will work only if the installed email client supports MAPI (Mail API, supported by most modern Windows e-mail programs).
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
W97M/Nail will start a new MAPI session and logon as the current user. It will use a random number to select the message out of four different possibilities:
1. Subject: Good Times Text: New information on this apparent hoax.. 2. Subject: New Developments Text: I thought you should know about this recent development... 3. Subject: WWIII! Text: Check out CNN.Com or read this 4. Subject: Market share tipoff... Text: Please don't share this information with anyone
Next, it will add the name of the user to the end of the message. After that, the worm will add the message to the outbox and collect every address from the user's address book. The worm will add all collected addresses to the receiver of the message and attachs itself (ActiveDocument) to the message. This way the users who receive the attachment and open it with Microsoft Word 97 will spread the worm to the users from their address book.
The worm will also create another message from the collected address book and a random message from user's inbox. This message will be sent to an email address (firstname.lastname@example.org) which probably belongs to the virus writer.
Finally it will send both messages and close the MAPI session.
The virus code contains this comment:
<!--1nternal--> Automated Chain Mail v0.1
Technical Details: Katrin Tocheva and Sami Rautiainen, F-Secure