W32.Munia

SUMMARY

W32.Munia is a virus that infects executable files when the target file is opened. It also steals password information.

Protection

• Virus Definitions (LiveUpdate™ Daily) August 5, 2006
• Virus Definitions (LiveUpdate™ Weekly) August 9, 2006
• Virus Definitions (Intelligent Updater) August 5, 2006
• Virus Definitions (LiveUpdate™ Plus) August 5, 2006

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Medium
• Payload: Infects executable files when the target file is opened and steals password information.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When the virus executes it performs the following actions:

1. Creates the following files:
   
   
   • %Windir%Downloaded Program Filesmuniu.dll
   • %Windir%Downloaded Program Filesmuniu.exe
   • %Windir%undll32.exe
   • %CurrentFolder%Thumbs.bd
     
     Note:
   • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:Windows or C:Winnt.
   • %CurrentFolder% is a variable that refers to the folder where the risk was originally executed.
     
     
2. Adds the following registry entry:
   
   "nvsetup" = "%Windir%Downloaded Program Filesmuniu.exe"
   
   to the following registry subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that it executes every time Windows starts.
   
   
3. Deletes the following registry subkey:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunMsgCenterExe
   
   
4. Adds the following registry entry:
   
   "Checkedvalue" = "0"
   
   to the following registry subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerAdvancedFolderHiddenSHOWALL
   
   in order to hide installed files and folders.
   
   
5. May attempt to hijack the "Routing and Remote Access" service by setting the value:
   
   "ImagePath" = "%Windir%Downloaded Program Filesmuniu.exe"
   
   in the following registry subkey:
   
   HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesRemoteAccess
   
   
6. Adds the following registry entry:
   
   "Start" = "2"
   
   to the following registry subkey:
   
   HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesRemoteAccess
   
   
7. Drops and injects munia.dll into all processes that are currently running.
   
   
8. Steals account information for the following game:
   
   Legend of Mir
   
   
9. Sends the above harvested information to URLs under the following address using the explorer.exe process:
   
   [http://]www.hxing2.com/m[REMOVED]
   
   
10. Attempts to infect .exe files on the compromised computer. Any files infected with this virus will be detected as W32.Munia!inf.

Recommendations

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

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Restart the computer in Safe mode.
4. Run a full system scan.
5. Delete any values added to the registry.
   

For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

• How to disable or enable Windows Me System Restore
• How to turn off or turn on Windows XP System Restore

Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article: Antivirus Tools Cannot Clean Infected Files in the _Restore Folder (Article ID: Q263455).

2. To update the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:

• Running LiveUpdate, which is the easiest way to obtain virus definitions:
  • If you use Norton AntiVirus 2006, Symantec AntiVirus Corporate Edition 10.0, or newer products, LiveUpdate definitions are updated daily. These products include newer technology.
  • If you use Norton AntiVirus 2005, Symantec AntiVirus Corporate Edition 9.0, or earlier products, LiveUpdate definitions are updated weekly. The exception is major outbreaks, when definitions are updated more often.
• Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to Virus Definitions (Intelligent Updater).
  
  The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions. For detailed instructions read the document: How to update virus definition files using the Intelligent Updater.

3. To restart the computer in Safe mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode. For instructions, read the document, "How to start the computer in Safe Mode."

4. To run a full system scan

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document: How to configure Norton AntiVirus to scan all files.
   • For Symantec AntiVirus Enterprise products: Read the document: How to verify that a Symantec Corporate antivirus product is set to scan all files.
2. Run a full system scan.
3. If any files are detected, follow the instructions displayed by your antivirus program.
   
   Note: The virus may cause some files to be corrupted. In such cases, repair will not be successful.

After the files are deleted or repaired, restart the computer in Normal mode and proceed with the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

Title: [FILE PATH]
Message body: Windows cannot find [FILE NAME]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.


5. To delete the value from the registry
Important: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified subkeys only. For instructions refer to the document: How to make a backup of the Windows registry.

1. Click Start > Run.
2. Type regedit
3. Click OK.
   
   Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.
   
   
4. Navigate to the subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
5. In the right pane, delete the value:
   
   "XXentryXX" = "XXvalueXX"
   
   
6. Exit the Registry Editor.