W32.Navidad - Removal

The Symantec AntiVirus Research Center (SARC) has developed a tool to help you repair the damage done by the worm. The W32.Navidad Fix Tool, and instructions on how to use it, are available here.

If you prefer to remove the worm without using the tool, or if the tool does not work on your computer, then follow the instructions in each section in the order shown. We strongly recommend that you read and understand the entire procedure before proceeding.

To remove this worm, you must do the following:

• Copy Regedit.exe to Regedit.com (in some cases).
• Edit the registry, and remove keys and changes made by the worm.
• Set Windows to show all files.
• Delete files placed on the computer by the worm.
• Run a full system scan.

To copy Regedit.exe to Regedit.com:
If you cannot start program files, or if you see the message "Windows cannot find winsvrc.exe," then you'll need to copy Regedit.exe to Regedit.com.

1. Do one of the following, depending on which operating system you have installed:
   • Windows 95/98. Click Start, point to Programs, and then click MS-DOS Prompt.
   • Windows Me. Click Start, point to Programs, point to Accessories, and then click MS-DOS Prompt.
   • Windows 2000.
     1. Click Start, and click Run.
     2. Click Browse, and then browse to the \Winnt\System32 folder.
     3. Double-click the Command.com file, and then click OK.
     4. Type cd \winnt and then press Enter.
2. Type copy regedit.exe regedit.com and then press Enter.
3. Type start regedit.com and then press Enter.
4. Proceed to the section "To edit the registry and remove keys and changes made by the worm."
   
   NOTE: This will open the Registry Editor in front of the DOS window. After you finish editing the registry and have closed the Registry Editor, close the DOS window as well.

To edit the registry and remove keys and changes made by the worm:
Follow these steps to undo the changes made to the Windows registry:

CAUTION: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry can result in permanent data loss or corrupted files. Please make sure you modify only the keys specified in this document. For more information about how to back up the registry, please read the document How to back up the Windows registry before proceeding with the following steps. If you are concerned that you cannot follow these steps correctly, then please do not proceed. Consult a computer technician for more information.

1. Start the Registry Editor if necessary:
   • If you have performed the procedure in the previous section, the Registry Editor is already open. Skip to step 4.
   • If it was not necessary to perform the procedures in the previous section, go on to step 2.
2. Click Start, and click Run. The Run dialog box appears.
3. Type regedit and then click OK. The Registry Editor opens.
   
   NOTE: If you see an error message or the Registry Editor does not open, go back to and follow the instructions in the previous section.
   
4. Navigate to and delete the following keys:
   
   NOTE: It is likely that you will find only one.
   
   HKEY_CURRENT_USER\Software\Navidad
   HKEY_CURRENT_USER\Software\Emanuel
   
5. Navigate to and select the following key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   
6. In the right pane, look for and select any of the following values that exist:
   
   Win32BaseServiceMOD         C:\Windows\System\winsvrc.exe
   Win32BaseServiceMOD         C:\Windows\System\wintask.exe
   
   NOTE: Some other variants of this have been seen, such as win b service. If in doubt, delete it. Removing items from the \Run key does not actually delete files from the hard disk--it only prevents them from being run when the computer starts.
   
7. Press Delete, and then click Yes to confirm.
8. Navigate to and select the following key:
   
   HKEY_CLASSES_ROOT\exefile\shell\open\command
   
   CAUTION: 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 an .exe extension from running. Make sure you browse all the way along this path until you reach the \command subkey.
   Do not modify the HKEY_CLASSES_ROOT\.exe key.
   Do modify the HKEY_CLASSES_ROOT\exefile\shell\open\command subkey that is shown in the following figure:
   
   
   <<=== NOTE: This is the key that you need to modify.
   
   
9. Double-click the (Default) value in the right pane.
10. Delete the current value data, and then type: "%1" %* (That is, type the following characters: quote-percent-one-quote-space-percent-asterisk.)
    
    NOTE: The Registry Editor will automatically enclose the value within quotation marks. When you click OK, the (Default) value should look exactly like this: ""%1" %*"
    
11. Make sure you completely delete all value data in the command key prior to typing the correct data. If a space is left accidentally at the beginning of the entry, any attempt to run program files will result in the error message, "Windows cannot find .exe." or "Cannot locate C:\ <path and file name>." If this happens to you, start over at the beginning of this document, making sure to completely remove the current value data.
    
12. Restart the computer.

To set Windows to show all files:
You need to do this to make sure that you can find the files installed by W32.Navidad.

1. Start Windows Explorer.
2. Click the View menu (Windows 95/98) or the Tools menu (Windows Me), and then click Options or Folder Options.
3. Click the View tab, and uncheck "Hide file extensions for known file types."
4. Click Show all files, and click OK.

To delete the files left by the worm:
To delete the files installed by W32.Navidad, follow these steps:

1. Click Start, point to Find or Search, and then click Files or Folders.
2. Make sure that "Look in" is set to (C:) and that Include subfolders is checked.
3. In the "Named" or "Search for..." box, type--or copy and paste--the following:
   
   navidad*.exe
   
4. Click Find Now or Search Now.
5. Delete any copies that you find.
6. Delete the text navidad*.exe from the "Named" or "Search for..." box.
7. In the "Named" or "Search for..." box, type--or copy and paste--the following:
   
   winsvrc.* winsvic.* wintask.* emanuel*.exe
   
8. Click Find Now or Search Now.
9. Delete any files named Winsvrc.exe, Winsvrc.vxd, Winsvic.vxd, Wintask.exe, Wintask.vxd, or Emanuel.exe that you find.
   
   NOTE: If Norton AntiVirus is installed and running on this computer, you may be alerted that the files are infected when you complete the previous steps. If that happens, choose Delete, and ignore any subsequent Windows messages saying that the file cannot be deleted. (This is Windows alerting you that it cannot find the specified file. It cannot find the file because it has already been deleted by Norton AntiVirus.)
   
10. Close the Find or Search window.
11. Right-click the Recycle Bin icon on the Windows desktop, and click Empty Recycle Bin.
    

To run a full system scan:
Start Norton AntiVirus (NAV), and make sure the your virus definitions are dated November 9, 2000, or later. If they are not, then run LiveUpdate. Finally, run a full system scan. If you have any version of NAV other than NAV 2001, then make sure that NAV is set to scan all files.

Technical Details