W32.Navidad.16896 - Removal

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:

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

For detailed instructions on how to do this, see the sections that follow.

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.16896.

1. Start Windows Explorer.
2. Click the View menu (Windows 95/98/NT) or the Tools menu (Windows Me/2000), and then click Options or Folder Options.
3. Click the View tab, and if necessary, uncheck "Hide file extensions for known file types."
4. Click Show all files, and then click OK.

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

1. Do one of the following, depending on which operating system you are running:
   • Windows 95/98 users: Click Start, point to Programs, and click MS-DOS Prompt.
   • Windows NT/2000 users:
     1. Click Start, and click Run.
     2. Click Browse, and browse to the \Winnt\system32 folder.
     3. Double-click the Command.com file, and then click OK.

1. Type copy regedit.exe regedit.com and press Enter.
2. Type start regedit.com and press Enter.
3. Proceed to the section "To edit the registry and remove keys and changes made by the worm."

NOTE: This will open Registry Editor in front of the DOS window. After you finish editing the registry and have closed Registry Editor, close the DOS window.

To edit the registry and remove keys and changes made by the worm:

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 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 Registry Editor if necessary:
   • If you 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 click OK. Registry Editor opens.
   
   NOTE: If you see an error message or Registry Editor does not open, go back to and follow the instructions in the previous section.
   
4. Navigate to and select the following key:
   
   HKEY_CURRENT_USER\Software\Emanuel
   
5. Press Delete, and then click Yes to confirm.
   
6. Navigate to and select the following key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   
7. Do one of the following:
   
   • Windows 95/98 users: In the right pane, look for and delete the following value:
     
     Win32BaseServiceMOD         C:\Windows\System\wintask.exe
     
   • Windows NT/2000 users: In the right pane, look for and delete the following value:
     
     Win32BaseServiceMOD         C:\Winnt\System32\wintask.exe
     
8. Press Delete, and click Yes to confirm.
9. 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.
   
   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.
   
10. In the right pane, double-click the (Default) value.
11. Delete the current value data, and then type: "%1" %* (That is, type the following characters: quote-percent-one-quote-space-percent-asterisk.)
    
    NOTE: Registry Editor will automatically enclose the value in quotation marks. When you click OK, the (Default) value should look exactly like this:
    ""%1" %*"
    
    Make sure you completely delete all value data in the command key prior to typing the correct data. If a space is left at the beginning of the entry, any attempt to run program files will result in the error message, "Windows cannot find .exe." 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 delete the files left by the worm:

1. Click Start, point to Find, and click Files or Folders.
2. Make sure that "Look in" is pointing your hard drive, or all drives if this is an option.
3. Type emanuel*.exe in the Named box, and click Find Now.
4. Delete any copies that you find.
5. Click New Search.
6. Type wintask.* in the Named box, and click Find Now.
7. Delete any files named Wintask.exe located in the C:\Windows\System folder.
   
   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 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.)
   
8. Close the Find: All Files window.
9. 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 27, 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 2000, then make sure that NAV is set to scan all files.

Technical Details