W32.Music.A.Worm

NOTE: For the purposes of this document, it is assumed that Windows is installed to C:\Windows. If your installation is different, please make the appropriate substitutions.

W32.Music.A.Worm is a worm that runs only on Windows 95 and Windows 98 systems. The worm needs a specific Win32 API that is only available in Windows 95 and Windows 98 versions of Kernel32.dll.

W32.Music.A.Worm has two components: a dropper component and a mailing component. When executed, the worm does the following:

1. Uses the mailing component to send an email message that contains the following subject and message:
   
   Subject: Testing to send file
   
   Message: Hi, just testing email using Merry Christmas music file, not bad music.
   
   The worm also attaches a copy of its dropper component with the file name Music.com.
   
2. The worm adds the value
   
   SysDrv      c:\windows\system\sysmcm.exe
   
   to the registry key
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
3. It creates a copy of the dropper component as \Windows\System\Sysmcm.exe.
4. It adds the registry key
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MCM
   
5. It creates the following registry entries in the key described in step 4:
   
   FirstRun
   RunMCM
   Version
   
6. The worm displays a cartoon picture of Santa Claus that is accompanied by music and a Merry Christmas message.

The worm may also attempt to download updated components of itself from specific Internet sites. If newer versions of its components are found, the worm installs these new components.

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