W32.Navidad.16896

W32.Navidad.16896 is a mass-mailing worm program that is very similar to W32.Navidad. The worm uses Microsoft Outlook to spread, using MAPI to reply to all Inbox messages that contain a single attachment. The worm utilizes the existing email subject line and body, and attaches itself as Emanuel.exe.
Removal tool link: http://securityresponse.symantec.com/avcenter/venc/data/w32.navidad.fix.html

Also Known As:	Navidad.E
Type:	Worm

Virus Definitions (Intelligent Updater) November 29, 2000

Wild Number of infections: 0 - 49 Number of sites: 3 - 9 Geographical distribution: Low Threat containment: Moderate Removal: Moderate

Threat Metrics Wild: Low Damage: Low Distribution: Medium

Damage

• Payload:
  • Modifies files: Registry keys are manipulated to autorun the worm.
  • Causes system instability: Can cause files with .exe extension not to run.

Distribution

• Subject of email: Same subject and body as the message that is replied to.
• Name of attachment: Emanuel.exe
• Size of attachment: 16,896 bytes

When executed, the worm does the following:

1. Displays a dialog box with a "winking smiley face" (emoticon):
   
   ;)
   
   and the title:
   
   Error
   
2. If you are running Windows NT/2000, the worm adds the following registry key:
   
   HKEY_CURRENT_USER\Software\Emanuel
   
   This key was supposed to be used to see if the computer was already infected. However, because of bugs in the code, the registry key is not utilized.
   
3. Next, the worm does one of the following:
   • If you are running Windows 95/98, the worm modifies the following registry key:
     
     HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
     Windows\CurrentVersion\Run
     
     and adds the value
     
     Win32BaseServiceMOD        \Windows\System\Wintask.exe
     
   • If you are running Windows NT/2000, the worm modifies the following registry key:
     
     HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
     Windows\CurrentVersion\Run
     
     and adds the value
     
     Win32BaseServiceMOD       C:\Winnt\System32\Wintask.exe
     
     
4. The worm then copies itself into the \Windows\System folder as Wintask.exe.
5. After the file has been copied, the worm modifies an additional registry key.
   
   • If you are running Windows 95/98, the worm changes
     
     HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\
     exefile\shell\open\command
     
     to equal
     
     \Windows\System\wintask.exe "%1" %*"
     
   • If you are running Windows NT/2000, the worm changes
     
     HKEY_CLASSES_ROOT\exefile\
     shell\open\command
     
     to equal
     
     C:\Winnt\System32\Wintask.exe "%1" %*"
     
6. Next, the worm begins the email routine. The worm utilizes MAPI to send mail and works with Microsoft Outlook. The worm checks for all messages in your Inbox and replies to those messages that have one attachment. The reply consists of the same subject line and body, but contains the worm attached as Emanuel.exe.
7. Finally, the worm places a flower icon in the system tray of the taskbar. When the mouse pointer is over the icon, the worm displays a yellow dialog box with the message:
   
   Come on lets party!!!
   
   NOTE: Once the infection occurs, a new flower icon will appear in the system tray each time that you attempt to run an executable file.
   
8. When you click the icon, a dialog box with a button appears. The button contains the text
   
   Nunca presionar este boton
   
   (Translation: Never press this button)
   
   • If you click the button, an error box with the title
     
     Emmanuel.....
     
     displays the message
     
     Emmanuel-God is with us!May god bless u.And Ash, Lk and LJ!!!
     
   • If you close the dialog box by clicking the X instead of clicking the button, the following message appears:
     
     May GOd bless u;D
     
     NOTE: The ;D is a "winking big grin emoticon."
     
     The box then closes.

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

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.

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.

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. 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.

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.
   

Write-up by: Andre Post