W97M.Melissa.U (Gen1)

The document infected with W97M.Melissa.U (Gen1) will arrive in an email with the following Subject line and body with a Word document attachment:

Subject: pictures USERNAME
Body: whats up?

USERNAME will be the name registered in the local copy of Word. For example, it may be "Subject: pictures John Doe". If you receive such an email, you should notify your system administrator immediately. Do not attempt to open the attached document.

There are three payloads.

As its primary payload, the virus will attempt to use Microsoft Outlook to e-mail a copy of the infected document to up to four email addresses. The email addresses are selected from Outlook's address book. Please note that a mailing-list (a list comprising more than one email address) within Outlook Address Book can be selected by the virus, which will then cause a larger distribution of email to be spammed. Corporations using Microsoft Exchange are the primary target of W97M.Melissa.U(Gen1) because the virus searches for Outlook's Address Book. This payload will only be executed once on each machine.

The second payload will insert the following text into the active document:

Please Check Outlook Inbox Mail<<<<

If you see such text in any of your documents, please be certain to scan your system using the latest virus definitions.

The third payload will delete the following files when the infected file is opened (making the system un-bootable):

· c:\command.com
· c:\io.sys
· d:\command.com
· d:\io.sys
· c:\Ntdetect.com
· c:\Suhdlog.dat
· c:\Ntdetect.com
· d:\Suhdlog.dat

All users are encouraged to confirm that macro virus protection is set to High in Word 2000, and enabled in Word 97.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
• Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
• Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
• Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
• If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
• If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
• For further information on the terms used in this document, please refer to the Security Response glossary.

Summary