W97M.Michael.Gen

This virus changes the following Microsoft Word options:

• It disables the Visual Basic Editor call from Microsoft Word by intercepting the ViewVBCode statement. This prevents you from viewing or editing the macro code.
• It disables the Options and Macros menu options by intercepting the ToolsOptions and ToolsMacro statements. Whenever the hooked commands are invoked, the following message is displayed instead:
  
  The utilities " [STATEMENT] "is not available at the standard edition of Microsoft Word, contact Microsoft for upgrade (cost of upgrade is minimal)
  
• It disables an option, so that when you open a document that contains a macro, the warning message no longer appears.

The virus becomes active when a Microsoft Word file is opened, saved or closed, or when a new document is created. When activated, the virus performs the following actions:

1. When you attempt to print a document, instead of your document being printed, the virus may drop and print the résumé text file C:Windows\Dummy.txt.
2. When a document is saved, it may display the following messages in the status bar:
   
   Michael Learns to Hack
   And Hope You'll Learn from It Too
   
3. It uses the Microsoft Office Assistant Balloon object to display various parts of the résumé.
4. The macro virus deletes the file C:\Msconfig.sys (if it exists) and then renames C:\Autoexec.bat to C:\Msconfig.sys.
5. The virus may also alter the following files:
   • C:\Windows\System\Main.cpl
   • C:\Windows\System\Kbdus.kbd
   • C:\Windows\System\Kbdusx.kbd

This can remap the keyboard keys and make the keyboard and mouse settings in the Control Panel unavailable.

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