W97M.Sting.B

SUMMARY

W97M.Sting.B is a macro virus that infects Microsoft Word templates and documents.

When an infected file is first opened the virus will disable the following:

• The prompt to confirm document conversions
• The Word macro security feature
• The prompt to save changes to the Normal.dot global template.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (LiveUpdate™ Weekly) March 6, 2005
• Virus Definitions (Intelligent Updater) March 4, 2005

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: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When W97M.Sting.B runs, it does the following:

1. Replaces the keybindings for CTRL+ALT+SHIFT+R and CTRL+ALT+SHIFT+V so that they will execute macros from within the virus. When CTRL+ALT+SHIFT+R is pressed, the virus will display the following dialog:
   
   
   • Macro Code Registration
   • Enter Registration Key
     
     
2. Displays the following, if the user enters OX3CCPYK9:
   
   Title: Microsoft Word
   Message: Macro code has been successfully registered. You need to restart your computer for the new setting to take effect.
   
   
3. Displays the following, if the user enters something other than OX3CCPYK9:
   
   Title: Microsoft Word
   Message: Incorrect Registration Key
   
   
4. Displays the following after pressing CTRL+ALT+SHIFT+R, if the computer has already been infected:
   
   Title: Microsoft Word
   Message: Macro code is already registered
   
   
5. Displays the following when CTRL+ALT+SHIFT+V is pressed:
   
   Title: View Macro Code
   Message: Access Code
   
   
6. Displays the following, if the correct password is not entered:
   
   Title: Microsoft Word
   Message: Incorrect Access Code
   
   
7. Intercepts the following file menu options and runs its own code in their place:
   
   
   • Open
   • Close
   • Save
   • Exit
   • New
   • Print
     
     
8. Checks if the document is already infected, when the user selects File/Save or File/Save As.
   
   If the document is not already infected the virus will create a copy of the document in %Windir%TEMP and add its code to that copy using the file %Windir%COMMANDZ.BAT.
   
   The virus will then copy the newly infected file to the location of the original file and delete the original file. The virus also deletes the copy from the Windows Temp folder.
   
   Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:Windows or C:Winnt.
   
   
9. Checks to see if the file being opened is infected, if the user selects File/Open. If it is not, it will infect the file using the method above.
   
   
10. Creates %Windir%COMMANDAZ.Bat, when the user selects File/Exit to copy %Windir%COMMANDy.y to the Normal.dot global template.
    
    Note: The actual file name has umlauts over the y
    
    
11. Deletes any *.do? files from %Windir%TEMP.
    
    
12. Creates %Windir%COMMANDXZ.bat to change attributes for files it drops in %Windir%COMMAND.
    
    
13. Edits the Autoexec.bat file to add %Windir%COMMAND to the file path.
    
    
14. Prints the document, if the user selects File/Print, then checks to see if the computer has been infected for 30 days or more.
    
    If the computer has been infected for more than 30 days and other conditions are met, the virus turns on the options to print drafts, field codes, and hidden text. The virus turns off the option to print drawing objects.
    
    The virus disables the ability to use printer metrics and Word 95 border rules. It enables the option to print forms data for the active document.
    
    
15. Replaces any user macro modules with its own module named Thunder, if the user creates a new document using File/New.
    
    
16. Re-enables the macro security settings and the prompt to save changes to Normal.dot, if the user selects Tools/Options. When the Options dialog is closed, the virus will disable them again. The virus will then save the original templates path to %Windir%TmpPath.Ini.
    
    
17. Clears the contents of the infected document and saves a copy of the file to the following locations, if the user selects File/Close:
    
    
    • %Windir%TEMP
    • %Windir%COMMAND
    • %Windir%
      
      
18. Disables ToolsMacroVisual Basic Editor, ToolsMacro, and ToolsCustomize by removing the macro functions they call.
    
    
19. Edits %SystemDrive%Autoexec.bat so that it will display "Thunder" in large letters on execution.
    
    Note: %SystemDrive% is a variable that refers to the drive on which Windows is installed. By default, this is drive C.

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. Run a full system scan and repair all the files detected as W97M.Sting.B.

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, re-enable 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: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
• 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 the Virus Definitions (Intelligent Updater).
  
  The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. To scan for and repair the infected files

1. Start your Symantec antivirus software 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 as infected with W97M.Sting.B, click Repair.
   
   Note: If your Symantec antivirus product reports that it cannot repair an infected file, Windows may be using the file. To fix this, run the scan in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode." Once you have restarted in Safe mode, run the scan again.
   
   When all the infected files have been repaired, restart the computer in Normal mode.