W32.Bigfairy.C@mm

SUMMARY

W32.Bigfairy.C@mm is a mass-mailing worm that uses Microsoft Outlook to send itself to all the contacts in the Outlook Address Book. The email has Chinese characters in the subject line and message.

The attachment is one of the following:

• Myphoto<a Chinese character>jpg.exe
• Islove<a Chinese character> jpg.exe
• Helpme<a Chinese character> jpg.exe

This threat is written in the Microsoft Visual Basic programming language.

Note: Definitions dated prior to April 19, 2004 detect this threat as W32.Mintop@mm.

Protection

• Virus Definitions (LiveUpdate™ Weekly) September 24, 2003
• Virus Definitions (Intelligent Updater) September 24, 2003

TECHNICAL DETAILS

When W32.Bigfairy.C@mm runs, it does the following:

1. Copies itself as the following:
   
   • %System%<a Chinese character>.exe
   • %System%<(five Chinese characters)>.exe
   • %Windir%Temporary Internet FilesHelpme.exe
   • %Windir%Temporary Internet FilesMyphoto.exe
   • %Windir%Temporary Internet FilesIslove.exe
   • %Windir%Temporary Internet FilesMyphoto<a Chinese character>jpg.exe
   • %Windir%Temporary Internet FilesIslove<a Chinese character> jpg.exe
   • %Windir%Temporary Internet FilesHelpme<a Chinese character> jpg.exe
     
     

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     Notes:
     %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:Windows or C:Winnt) and copies itself to that location.
     
     %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).

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2. May create one or more of the following temporary files while running:
   
   C:Pdos.sys
   C:Autoexec.sys
   %Windir%Temporary Internet FilesMsimnusa.sys
   
   

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   Note: These files contain only text and are not viral by themselves. Therefore, Symantec antivirus products do not detect them. Manually delete them if the worm has infected your system.

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3. Modifies the default value of the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftwindowscurrentVersionRun
   
   to:
   
   @="<(five Chinese characters)>"
   
   
4. Modifies the default value of the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftwindowscurrentVersionRunServices
   
   to:
   
   @="<a Chinese character>"
   
   
5. Modifies the default value of the registry key:
   
   HKEY_LOCAL_MACHINESOFTWARECLASSESinifileshellopencommand
   
   to one of the following:
   
   @="%Windir%Temporary Internet FilesMyphoto<a Chinese character>.jpg.exe"
   @="%Windir%Temporary Internet FilesIslove<a Chinese character>.jpg.exe"
   @="%Windir%Temporary Internet FilesHelpme<a Chinese character>.jpg.exe"
   
   
6. If the system is Windows 95/98/Me, the worm will register itself as a service process.
   
   
7. May overwrite the file, %Windir%SAMPLESWSHNetwork.vbs, with email addresses it retrieves from the Outlook Address Book.
   
   
8. Uses Microsoft Outlook to send itself to all the contacts in the Outlook Address Book. The email has Chinese characters in the subject line and message. The attachment is one of the following:
   
   • Myphoto<a Chinese character>jpg.exe
   • Islove<a Chinese character> jpg.exe
   • Helpme<a Chinese character> jpg.exe
     
     
9. Pings the following Web sites:
   
   • www.163.com
   • www.sina.com.cn
   • www.dell.com
   • www.microsoft.com
   • www.yn.cninfo.net
   • www.km169.net
     
     
10. If the current system date is December 24, the worm overwrites the file, %Windir%SAMPLESWSHRegistry.vbs. Then, the worm uses this Visual Basic (VB) script file to do the following:
    
    • Modifies the value data of the following registry key value names:
      
      HKEY_LOCAL_MACHINESoftwareMicrosoftInternet ExplorerMainWindow Title
      HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRegisteredOwner
      
      
    • Appends some code to all the .asp, .htm, .html, and .shtml files on all the drives, including the network drives. The code will display two messages:
      
      Title: Autumnal Fairy Tale
      Message: No War!Peace Banzai!
      
      Title: System Error!
      Message: Format Your Hard-Disk......
      
      
11. If the current country setting is "United States," the worm does the following:
    
    • Displays some dialog boxes, which contain political messages.
    • May perform some annoying action, such as opening and closing the CD-ROM drive.
    • Launches many Internet Explorer windows, which browse to mincer.top263.net.
    • Creates C:Winstart.bat, which contains code to format hard drive C.
    • Overwrites C:Autoexec.bat with the code to call C:Winstart.bat.

Recommendations

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.

REMOVAL

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

1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Run a full system scan and delete all the files detected as W32.Bigfairy.C@mm.
4. Delete the value that was added to the registry.
5. Manually delete the files that the worm created or overwrote.

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

1. Disabling 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"
  

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Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.

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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.

2. 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.

3. 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 W32.Bigfairy.C@mm, click Delete.

4. Deleting the value from the registry

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WARNING: 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.

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1. Click Start, and then click Run. (The Run dialog box appears.)
   
2. Type regedit
   
   Then click OK. (The Registry Editor opens.)
   
   
3. Navigate to each of the following keys,
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunServices
   
   and in the right pane, delete the value data of the "(Default)" value (it should be blank).
   
   
4. Navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWARECLASSESinifileshellopencommand
   
   
5. In the right pane, modify the value data of the "(Default)" value to:
   
   %Windir% otepad.exe %1
   
   
6. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftInternet ExplorerMain
   
   
7. In the right pane, delete the value:
   
   Window Title
   
   
8. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersion
   
   
9. In the right pane, modify the value data of "RegisteredOwner".
   
   
10. Exit the Registry Editor.

5. Manually deleting the files that the worm created or overwrote
Using Windows Explorer, delete the following files, which the worm created or overwrote.

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Note: You may wish to verify that the worm overwrote the files prior to deleting them.

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• C:Winstart.bat
• C:Autoexec.bat
• C:Pdos.sys
• C:Autoexec.sys
• %Windir%Temporary Internet FilesMsimnusa.sys
• %Windir%SAMPLESWSHNetwork.vbs
• %Windir%SAMPLESWSHRegistry.vbs