W32.Chod.D - Removal

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

1. Reinstall your Symantec antivirus program.
2. Disable System Restore (Windows Me/XP).
3. Remove all the entries that the risk added to the hosts file.
4. Update the virus definitions.
5. Run a full system scan and delete all the files detected.
6. Edit the Win.ini file.
7. Delete any values added to the registry.
8. Restore the Windows Security Center.
   

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

1. To reinstall your Symantec antivirus program
As this risk attempts to remove the files and registry subkeys that your Symantec antivirus program uses, you may need to reinstall the program. If your Symantec antivirus program is not working properly, uninstall, and then reinstall it.

2. 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).

3. To remove all the entries that the risk added to the hosts file

1. Navigate to the following location:
   
   
   • Windows 95/98/Me:
     %Windir%
   • Windows NT/2000/XP:
     %Windir%\System32\drivers\etc
     
     Notes:
   • The location of the hosts file may vary and some computers may not have this file. There may also be multiple copies of this file in different locations. If the file is not located in these folders, search your disk drives for the hosts file, and then complete the following steps for each instance found.
   • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows (Windows 95/98/Me/XP) or C:\Winnt (Windows NT/2000).
     
     
2. Double-click the hosts file.
3. If necessary, deselect the "Always use this program to open this program" check box.
4. Scroll through the list of programs and double-click Notepad.
5. When the file opens, delete all the entries added by the risk. (See the Technical Details section for a complete list of entries.)
6. Close Notepad and save your changes when prompted.

4. 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 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 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.

5. To scan for and delete 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, click Delete.
4. Click Start > Programs > Accessories > Windows Explorer
5. Navigate to and delete the file %UserProfile%\Start Menu\Programs\Startup\csrss.lnk.
6. Exit Windows Explorer.

Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do 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.

After the files are deleted, 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.

6. To edit the Win.ini file
If you are running Windows 95/98/Me, follow these steps:

1. Click Start > Run.
2. Type the following:
   
   edit c:\windows\win.ini
   
   and then click OK.
   
   (The MS-DOS Editor opens.)
   
   NOTE: If Windows is installed in a different location, make the appropriate path substitution.
   
   
3. In the [windows] section of the file, look for lines similar to:
   
   run = %System%\[RANDOM FOLDER NAME]\csrss.exe
   load = %System%\[RANDOM FOLDER NAME]\csrss.exe
   
   
4. If this lines exist, delete everything to the right of run= and load =
   
   
5. Click File > Save.
6. Click File > Exit.
   

7. 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 subkeys:
   
   HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   
5. In the right pane, delete the value:
   
   "csrss" = ""
   
   
6. Navigate to the subkey:
   
   HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
   
   
7. In the right pane, delete the values:
   
   "Load" = "%System%\[RANDOM FOLDER NAME]\csrss.exe"
   "Run" = "%System%\[RANDOM FOLDER NAME]\csrss.exe"
   
   
8. Navigate to the subkeys:
   
   HKEY_CURRENT_USER\SOFTWARE\Chode
   HKEY_CLASSES_ROOT\Chode
   
   
9. In the right pane, delete the value:
   
   "Installed" = "1"
   
   
10. Navigate to the subkey:
    
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Explorer\Advanced
    
    
11. In the right pane, reset the values:
    
    "Hidden" = "2"
    "SuperHidden" = "0"
    "ShowSuperHidden" = "0"
    
    
12. Navigate to the subkeys:
    
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Policies\System
    
    
13. In the right pane, reset the values:
    
    "DisableRegistryTools" = "1"
    "NoAdminPage" = "1"
    
    
14. Exit the Registry Editor.

8. To restore the Windows Security Center
This risk attempts to disable the features in the Windows Security Center, available in Windows XP Service Pack 2. If you are running Windows XP Service Pack 2 and would like to restore the full functionality of the Windows Security Center, please complete the following steps:

Important: If your computer is connected to a domain, you may not be able to adjust these settings. If so, contact your network administrator for more information.

1. Click Start > Control Panel.
2. Double-click the Security Center.
3. In the right pane, click Windows Firewall. The Windows Firewall appears.
4. Select On.
5. Click OK to close the Windows Firewall.
6. In the left pane of the Security Center, select Change the way Security Center alerts me.
7. Click Alert Settings.
8. Select Alert Settings, Firewall, and Virus Protection.
9. Click OK
10. Click Automatic Updates.
11. Select Automatic.
12. Click OK.
13. Exit the Security Center.

Technical Details