W32.Mockbot.A.Worm

1. Attempts to copy itself as the files:
   
   • %System%\msnet.exe
   • %StartMenu%\Programs\Startup\msnet.exe
     
     

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     Notes:
   • %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
   • %StartMenu% is a variable. The worm locates the Start Menu folder and copies itself to that location. By default, this is C:\Windows\Start Menu (Windows 95/98/Me) or C:\Documents and Settings\<current user>\Start Menu (Windows Windows NT/2000/XP).

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2. Spawns a thread that attempts to create the following registry key values below, and then monitors them. The thread will recreate the values if they are deleted.
   
   
3. Adds the value:
   
   "Microsoft Network" = "%System%\msnet.exe"
   
   to one or more of the following registry keys:
   
   • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
     Run
   • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
     RunOnce
   • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
     RunServices
   • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
     RunServicesOnce
   • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
     Run
   • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
     RunOnce
   • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
     RunServices
   • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
     RunServicesOnce
     
     so that the worm is executed on startup.
     
     
4. Adds the values:
   
   • "Enable"="Yes"
   • "Path"="%System%\msnet.exe"
   • "Parametres"=""
   • "Startup"="%System%\msnet.exe"
     
     to the registry key:
     
     HKEY_CURRENT_USER\Software\Mirabilis\ICQ\Agent\Apps\icqstub
     
     so that the worm is executed any time ICQ is started.
     
     
5. Attempts to create the service, "Microsoft Network," so that the worm is executed with system-level access privileges on startup.
   
   
6. Spawns a thread that monitors running processes, killing any found on a large list of antivirus, firewall, and security product process names, as well as some viruses and malware. For more details, see the list in the "Additional Information" section below.
   
   
7. The worm will randomly generate IP addresses and use each of the following methods to try to infect computers at each IP:
   
   • Checks whether the computer is infected with W32.Mydoom.A@mm or Backdoor.Optix. The worm does this by attempting to connect to the computer on ports 3127 and 3410. If these backdoors are found, the worm will install itself on the host.
   • Attempts to connect to the computer on port 6129, looking for the DameWare Mini Remote Control server application. If found, the worm will take advantage of a vulnerability in the application to install itself on the computer.
   • Sends data on TCP port 135 that may exploit the DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-026). The worm sends one of two types of data, which exploits either Windows XP or Windows 2000. If the exploit is successful, the worm will install itself on the remote host.
     
     
8. Opens a backdoor listening for connections on port 69.
   
   
9. Connects to predetermined IRC servers and joins a channel to listen for commands from an attacker. The worm will report its status and information on any other infected computers.

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.