Trojan.Gutta - Removal

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

1. Reverse the changes that were made to the registry.
2. Disable System Restore (Windows Me/XP).
3. Update the virus definitions.
4. Run a full system scan and delete all the files detected as Trojan.Gutta.
   

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

1. Reversing the changes that were made to the registry.
Because the worm modified the registry so that you cannot run any .exe files, first make a copy of the Registry Editor as a file with the .com extension, and then run that file.

1. Do one of the following, depending on the version of Windows you are running:
   • Windows 95/98 users:
     1. Click Start.
     2. Point to Programs.
     3. Click the MS-DOS Prompt. (A DOS window opens at the C:\Windows prompt.) Proceed to step B of this section.
        
        
   • Windows Me users:
     1. Click Start.
     2. Point to Programs.
     3. Point to Accessories.
     4. Click the MS-DOS Prompt. (A DOS window opens at the C:\Windows prompt.) Proceed to step B of this section.
        
        
   • Windows NT/2000 users:
     1. Click Start, and then click Run.
     2. Type command, and then press Enter. (A DOS window opens.)
     3. Type cd \winnt, and then press Enter.
     4. Go to step B of this section.
        
        
   • Windows XP users:
     1. Click Start, and then click Run.
     2. Type command, and then press Enter. (A DOS window opens.)
     3. Type the following:
        
        cd\
        cd \windows
        
        Press Enter after typing each one.
        
        
     4. Proceed to step B of this section.
        
        
2. Type copy regedit.exe regedit.com
   
   and then press Enter.
   
   
3. Type start regedit.com
   
   and then press Enter. (The Registry Editor opens in front of the DOS window.)
   
   After you finish editing the registry, exit the Registry Editor, and then exit the DOS window as well.
   
   
4. Before continuing, 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 keys only. For instructions, read the document, "How to make a backup of the Windows registry."
   
   
5. Navigate to and select the key:
   
   HKEY_CLASSES_ROOT\exefile\shell\open\command
   
   NOTE: The HKEY_CLASSES_ROOT key contains many subkey entries that refer to other file extensions. One of these file extensions is .exe. Changing this extension can prevent any files ending with a .exe extension from running. Make sure that you completely browse through this path until you reach the \command subkey.
   
   Modify the HKEY_CLASSES_ROOT\exefile\shell\open\command subkey, shown in the following figure:
   
   <<=== NOTE: Modify this key.
   
   
6. In the right pane, double-click the (Default) value.
7. Click in the Value data field to the right of the text so that the current value data is no longer selected in blue.
8. Backspace to delete the characters:
   
   hahafool
   
   Make sure that you do not delete the text:
   
   "%1" %*
   
   
9. Click OK.
   
   
10. Navigate to the key:
    
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    
    
11. In the right pane, delete the value:
    
    "rundll32"="C:\Windows\CSRSS.exe"
    
    
12. Exit the Registry Editor.
    

2. Disabling 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"

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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.

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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.

3. Updating 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 on U.S. business days (Monday through Friday). 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.

4. Scanning for and deleting the infected files

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 as infected with Trojan.Gutta, click Delete.

Technical Details