W32.HLLW.BenfGame.B

SUMMARY

W32.HLLW.BenfGame.B is written in the Delphi programming language. It has a password-stealing component and a worm component. W32.HLLW.BenfGame.B spreads to all the mapped and network-shared drives under an assortment of randomly generated filenames.

Protection

• Virus Definitions (LiveUpdate™ Weekly) June 3, 2003
• Virus Definitions (Intelligent Updater) June 3, 2003

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: Medium
• Modifies Files: Drops files.
• Releases Confidential Info: Password-stealing component.
• Causes System Instability: Can cause instability if the files that are referenced in the registry are not found.
• Compromises Security Settings: Attempts to terminate the processes of some antivirus programs.

Distribution

• Distribution Level: Medium
• Shared Drives: Copies itself to randomly selected folders on all the mapped and shared drives.

TECHNICAL DETAILS

The password-stealing component of W32.HLLW.BenfGame.B only applies when Chinese ICQ (OICQ) is installed. The Trojan sends the passwords to its creator via OICQ. The sent information for the password stealer is stored in the file, Msread.dt.

The worm component is independent of the Trojan component. When the worm is run, it does the following:

1. Creates shares for the local and network drives.
   
   
2. Copies itself to randomly selected folders on all the mapped and shared drives.
   
   
3. Copies itself with filenames, composed of random letters, such as Xwsqz.exe.
   
   
4. Creates the file, C:Filedebug, with a list of the filenames that the worm created.
   
   
5. Randomly registers some of the dropped files as processes.
   
   
6. Makes the following modifications to these registry keys:
   
   HKEY_CLASSES_ROOT xtfileshellopencommand
   Replaces the reference to notepad.exe with one of the random filenames that the worm created.
   
   HKEY_CLASSES_ROOTchm.fileshellopencommand
   Replaces the references to hh.exe with one of the random filenames that the worm created.
   
   HKEY_CLASSES_ROOTscrfileshellopencommand
   Changes the key to include one of the random filenames that the worm created, so that the key is <garbage file name> %1".
   
   HKEY_CLASSES_ROOTegfileshellopencommand
   Replaces the reference to regedit.exe with one of the random filenames that the worm created.
   
   HKEY_CLASSES_ROOTinifileshellopencommand
   Replaces the reference to any application with one of the random filenames that the worm created.
   
   HKEY_CLASSES_ROOTexefileshellopencommand
   Changes the key to include one of the random filenames that the worm created, so that the key is <garbage file name> "%1" %*".
   
   
7. Adds a value, which refers to the worm, to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   The value has a randomly chosen name, and the Value data is not always the same. For example, the file Qwoes.exe might have a Value data of "C:program filesApflsw.exe."
   
   
8. Adds the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionwin70workfile
   
   with a random Value.
   
   
9. Tries to disable the following NT processes:
   • kav9x.exe
   • kavsvc9x.exe
   • kavsvcui.exe
   • kav32.exe
   • smenu.exe
   • ravmon.exe
   • passwordguard.exe
   • vpc32.exe
   • watcher.exe
     
     
10. Creates the file, called Autorun.inf, in the root of all the drives, except the C: drive.
    
    This file contains the text:
    
    [autorun]
    OPEN= <random file name generated by the worm>

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.HLLW.BenfGame.B. Delete the Autorun.inf file from the root of all the drives, except drive C, if it exists.
4. Reverse the changes that were made to the registry.

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"

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.HLLW.BenfGame.B, click Delete.
4. Delete the Autorun.inf file from the root of all the drives, except drive C, if it exists.

4. Reversing the changes made to the registry

Copying Regedit.exe to Regedit.com and editing the registry
Because the worm modified the registry, first make a copy of the Registry Editor as a file with the .com extension, and then run the file.

1. Do one of the following, depending on the version of Windows you are running:
   • Windows 95/98 users:
     1. Click Start.
     2. Point to Programs.
     3. Click the MS-DOS Prompt. (A DOS window opens at the C:Windows prompt.) Proceed to step b of this section.
   • Windows Me users:
     1. Click Start.
     2. Point to Programs.
     3. Point to Accessories.
     4. Click the MS-DOS Prompt. (A DOS window opens at the C:Windows prompt.) Proceed to step b of this section.
   • Windows NT/2000 users:
     1. Click Start, and then click Run.
     2. Type command, and then press Enter. (A DOS window opens.)
     3. Type cd winnt, and then press Enter.
     4. Go to step b of this section.
   • Windows XP users:
     1. Click Start, and then click Run.
     2. Type command, and then press Enter. (A DOS window opens.)
     3. Type the following:
        
        cd
        cd windows
        
        Press Enter after typing each one.
        
     4. Proceed to step b of this section.
        
        
2. Type copy regedit.exe regedit.com
   
   and then press Enter.
   
   
3. Type start regedit.com
   
   and then press Enter. (The Registry Editor opens in front of the DOS window.)
   
   After you finish editing the registry, exit the Registry Editor, and then exit the DOS window as well.
   
   
4. Before continuing, 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. For instructions, read the document, "How to make a backup of the Windows registry."
   
   
5. Next you must restore to their original values all of the keys that the worm modified. Navigate to and select in turn each of the following keys, and restore them to the values that are shown for each one:
   
   Key:HKEY_CLASSES_ROOT xtfileshellopencommand
   Restore value to: notepad.exe %1
   
   Key: HKEY_CLASSES_ROOTchm.fileshellopencommand
   Restore value to: hh.exe %1
   
   Key: HKEY_CLASSES_ROOTscrfileshellopencommand
   Restore value to: %1/S
   
   Key: HKEY_CLASSES_ROOTegfileshellopencommand
   Restore value to:  regedit.exe %1
   
   Key: HKEY_CLASSES_ROOTinifileshellopencommand
   Restore value to: notepad.exe %1
   
   Key: HKEY_CLASSES_ROOTexefileshellopencommand
   Restore value to: %1 % *
   
   
6. Delete the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionwin70workfile
   
   
7. Navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
8. In the right pane, delete the value that refers to the worm.
   
   
9. Exit the Registry Editor.