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  2. Security Response/
  3. Trojan.Benfgame

Trojan.Benfgame - Removal

Discovered:
August 23, 2002
Updated:
February 13, 2007 11:46:33 AM
Also Known As:
Trojan.Benfgame.214310
Type:
Trojan Horse
Systems Affected:
Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP

NOTES:
  • These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  • If Trojan.Benfgame has run, it makes changes to the registry as previously described. Some of the (Default) values that it changes vary depending on the operating system. The following is an outline of the basic procedure that is needed, followed by step-by step instructions. However, because the (Default) values can vary, unless you are sure of what these values should be on your computer, we suggest that you obtain the services of a qualified computer consultant.
  1. Update the virus definitions, run a full system scan, and delete all files that are detected as Trojan.Benfgame.
  2. Delete the text that the Trojan added to Win.ini.
  3. Copy Regedit.exe as Regedit.com.
  4. Delete the value

    MSBenCheck %system%\MSBFRUN2.EXE

    from the registry key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  5. Change the (Default) values back to their original values
For details on how to do this, read the following instructions.

To delete the text that the Trojan added to Win.ini
This is necessary only on computers that are running Windows 95/98/Me.

NOTE: (For Windows Me users only) Due to the file-protection process in Windows Me, a backup copy of the file that you are about to edit exists in the C:\Windows\Recent folder. Symantec recommends that you delete this file before you continue with the steps in this section. To do this using Windows Explorer, go to C:\Windows\Recent, and in the right pane select the Win.ini file and delete it. It will be regenerated as a copy of the file that you are about to edit when you save your changes to that file.
  1. Click Start, and click Run.
  2. Type the following, and then click OK.

    edit c:\windows\win.ini

    The MS-DOS Editor opens.

    NOTE: If Windows is installed in a different location, make the appropriate path substitution.
  3. In the [windows] section of the file, look for an entry similar to the following:

    run=%windir%\MSCVT2.EXE
  4. Select the entire line. Be sure that you have not selected any other text, and then press Delete.
  5. Click File, and click Save.
  6. Click File, and click Exit.

To scan for and delete the infected files:
  1. Obtain the most recent virus definitions. There are two ways to do this:
    • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
    • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

      Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.
  2. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
  3. Run a full system scan.
  4. If any files are detected as infected with Trojan.Benfgame, click Delete.

To copy Regedit.exe as Regedit.com:
Because the worm modified the registry so that you cannot run .exe files, you must first make a copy of the Registry Editor as a file with the .com extension and then run that file.
  1. Do one of the following, depending on which version of Windows you are running:
    • Windows 95/98 users: Click Start, point to Programs, and click MS-DOS Prompt. This opens a DOS window at the C:\Windows prompt. Go on to step 2 of this section.
    • Windows Me users: Click Start, point to Programs, point to Accessories, and then click MS-DOS Prompt. This opens a DOS window at the C:\Windows prompt. Go on to step 2 of this section.
    • Windows NT/2000 users:
      1. Click Start, and click Run.
      2. Type the following, and then press Enter:

        command

        A DOS window opens.
      3. Type the following, and then press Enter:

        cd \winnt
      4. Go on to step 2 of this section.
    • Windows XP:
      1. Click Start, and click Run.
      2. Type the following, and then press Enter:

        command

        A DOS window opens.
      3. Type the following commands (press Enter after typing each one):

        cd\
        cd \win
        dows
      4. Proceed to step 2 of this section.
  2. Type the following, and then press Enter:

    copy regedit.exe regedit.com
  3. Type the following, and then press Enter:

    start regedit.com

    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.
1. Proceed to the next section, "To remove the added value and restore the (Default) values:," only after you have accomplished the previous steps.

NOTES:
  • The Registry Editor will open in front of the DOS window. After you finish editing the registry and close the Registry Editor, then close the DOS window.
  • After you remove BackDoor.Benfgame, then you may delete the Regedit.com file.

To delete the value that the Trojan added and restore the (Default) values:

CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
  1. Click Start, and click Run. The Run dialog box appears.
  2. Type regedit and then click OK. The Registry Editor opens.
  3. Navigate to the key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, delete the value

    MSBenCheck %system%\MSBFRUN2.EXE
  5. For each of these keys, follow the instructions in steps 6 and 7:

    HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\txtfile\shell\open\command
    HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\exefile\shell\open\command
    HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\scrfile\shell\open\command
    HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\chm.file\shell\open\command

  6. For each one, double-click the (Default) value in the right pane, .
  7. Delete the current value data, and then replace it with the correct data for your operating system and installation. As mentioned previously, this can vary. For example, in a default installation of Windows 98, the (Default) values are:
    • HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\txtfile\shell\open\command

      (Default) C:\Windows\NOTEPAD %1
    • HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\exefile\shell\open\command

      (Default) "%1" %*
    • HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\scrfile\shell\open\command

      (Default) %1 /s
    • HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\chm.file\shell\open\command

      (Default) C:\Windows\hh.exe %1

  8. When you have finished, exit the Registry Editor and restart the computer.


Writeup By: Atli Gudmundsson

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