W32.Kifer

SUMMARY

W32.Kifer is a Trojan horse that drops BAT.Snoital@mm, which will attempt to delete antivirus software from your computer. It also spreads through MAPI-enabled email clients, such as Microsoft Outlook, and IRC.

The email has the following characteristics:

Subject: Symantec Security Alert
Attachment: Symantec_W32_Cure.bat

Protection

• Virus Definitions (LiveUpdate™ Weekly) February 11, 2004
• Virus Definitions (Intelligent Updater) February 10, 2004

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When W32.Kifer is executed, it performs the following actions:

1. Deletes the following files:
   
   • C:\%Program Files%kasper~1avp32.exe
   • C:\%Program Files% orton~1*.exe
   • C:\%Program Files% rojan~1 c.exe
   • C:\%Program Files% orton~1s32integ.dll
   • C:\%Program Files%f-prot95fpwm32.dll
   • C:\%Program Files%mcafeescan.dat
   • C:\%Program Files%ocem bav.dat
   • C:\%Program Files%avpersonalantivir.vdf
   • C: bavw95 bscan.sig
     
     

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     Note: %ProgramFiles% is a variable that refers to the path to the program files folder. By default, this is C:Program Files.

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2. Creates a batch file in various locations on the computer. For example:
   
   • porn.bat
   • 5111.bat
   • Symantec_W32_Cure.bat
   • masbl.bat
     
     

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     Note: The file names vary and may consist of random characters.

     ---

     
     
3. Creates several script files. Some file names include:
   
   • kazzad.vbs
   • nwboy.vbs
   • ghuux.vbs
   • szlhm.vbs
     
     
4. Sends email with the following characteristics:
   
   Subject: Symantec Security Alert
   Body: Symantec have revently discovered a cure for the very destructive worm W32/Mydoom@MM (SEE ATTACHEMNT). This worm installs a backdoor on the system letting attackers gain remote access it also attacks the mircosoft ssrver and LEAVES YOU THE USER TO BLAME.
   Attachment: Symantec_W32_Cure.bat
   
   
5. Adds the value:
   
   "DlDir0"="%Windir%kazaa"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwarekazaaTransfer
   
   

   ---

   Note: %Windir% is a variable. The Trojan locates the Windows installation folder (by default, this is C:Windows or C:Winnt) and copies itself to that location.

   ---

   
   
6. Adds the value:
   
   "kfienq"="%Windir%masbl.bat"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   

   ---

   Note: The value may vary, depending on the name and location of the batch file that was created in step 2.

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7. Modifies the mIRC script file, script.ini.
   
   
8. Modifies the pirch98 file, events.ini.

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. Restart the computer in Safe mode or VGA mode.
3. Delete the value that was added to the registry.
4. Restore Norton AntiVirus (if applicable).
5. Update the virus definitions.
6. Run a full system scan and delete all the files detected as BAT.Snoital@mm or W32.Kifer.
   

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 Trojan infects a computer, System Restore may back up the 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. Restarting the computer in Safe mode or VGA mode

Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.

• For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
• For Windows NT 4 users, restart the computer in VGA mode.

3. 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 the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the value that refers to any file detected as infected by W32.Kifer or BAT.Snoital@mm.
   
   For example:
   
   "kfienq"="%Windir%masbl.bat"
   
   
5. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwarekazaaTransfer
   
   
6. In the right pane, delete the value:
   
   "DlDir0"="%Windir%kazaa"
   
   
7. Exit the Registry Editor.
   
   
8. Restart the computer back into Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."

4. Restoring Norton AntiVirus (if applicable)
Since W32.Kifer attempts to delete the files associated with Norton AntiVirus, you may have to re-install this program. For more information on completing this process, read the document, "Restoring Norton AntiVirus after it is infected by a virus."

5. 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.

6. 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 BAT.Snoital@mm or W32.Kifer, click Delete.