Backdoor.NetTrojan - Removal

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

1. Reverse the changes made to the registry.
2. For Windows 95/98/Me only: Reverse the change made to the Win.ini file.
3. Update the virus definitions.
4. Run a full system scan and delete all the files detected as Backdoor.NetTrojan.

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

1. Reversing changes made to the registry

CAUTION: 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. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit, and then click OK. (The Registry Editor opens.)
3. Navigate to each of these keys:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
   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\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run
   HKEY_CURRENT_USER\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\RunServices
   HKEY_CURRENT_USER\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\RunOnce
   
   NOTE: Some of the keys may not exist on your system.
   
   
4. In the right pane, delete the value:
   
   WinLoader %windir%\UNWISE.EXE
   
   NOTE: This value may vary. Look for any value that refers to the files detected as Backdoor.NetTrojan.
   
   
5. Navigate to the following key:
   
   HKEY_LOCAL_MACHINE\Software\CLASSES\txtfile\shell\open\command
   
   
6. In the right pane, double-click the value:
   
   winampold
   
   
7. Copy the contents of "Value data:", then click OK.
   
8. In the right pane, double-click the value:
   
   (Default)
   
   
9. Paste the text from "winampold" into the "Value data:" text box.
   
10. Repeat steps f through i for each of the following keys:
    
    HKEY_LOCAL_MACHINE\Software\CLASSES\exefile\shell\open\command
    HKEY_LOCAL_MACHINE\Software\CLASSES\batfile\shell\open\command
    HKEY_LOCAL_MACHINE\Software\CLASSES\comfile\shell\open\command
    HKEY_LOCAL_MACHINE\Software\CLASSES\piffile\shell\open\command
    HKEY_LOCAL_MACHINE\Software\CLASSES\giffile\shell\open\command
    HKEY_LOCAL_MACHINE\Software\CLASSES\htmlfile\shell\open\command
    HKEY_LOCAL_MACHINE\Software\CLASSES\jpegfile\shell\open\command
    HKEY_LOCAL_MACHINE\Software\CLASSES\Word.Document.8\shell\open\command
    
    
11. Exit the Registry Editor.
    
12. Reboot the computer.
    
    NOTE: Windows 95/98/Me users should continue with section 2 before rebooting the computer.

2. For Windows 95/98/Me only: Reversing the change made to the Win.ini file

NOTE: If you are not running Windows 95, Windows 98, or Windows Me, skip to section 3.

1. The function you perform first depends on your operating system:
   • Windows 95/98: Go to step b.
   • Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made a backup copy of the Win.ini file that you are to edit. If this backup copy exists, it will be in the C:\Windows\Recent folder. Symantec recommends that you delete this file before continuing with the steps in this section. To do this:
     • Start Windows Explorer.
     • Browse to and select the C:\Windows\Recent folder.
     • In the right pane, select the Win.ini file and delete it. It will be regenerated when you save your changes to the Win.ini file in step f.
       
       
2. Click Start, and then click Run.
   
3. Type the following, and then click OK.
   
   edit c:\windows\system.ini
   
   (The MS-DOS Editor opens.)
   
   NOTE: If Windows is installed in a different location, make the appropriate path substitution.
   
   
4. In the [boot] section of the file, look for a line similar to the following:
   
   shell = Explorer.exe %windir%\UNWISE.EXE
   
   
5. If it exists, delete everything to the right of Explorer.exe. When you are done, it should look like:
   
   shell = Explorer.exe
   
   
6. Click File, and then click Save.
   
7. Click File, and then click Exit.
   
8. Reboot the computer.

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 Backdoor.NetTrojan, click Delete.

Technical Details