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Backdoor.Feardoor - Removal

Risk Level 1: Very Low

Discovered:
October 8, 2002
Updated:
February 13, 2007 11:59:16 AM
Also Known As:
Backdoor.Feardoor.161 [AVP]
Type:
Trojan Horse
Systems Affected:
Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP

NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  1. Update the virus definitions.
  2. Run a full system scan, and delete all files that are detected as Backdoor.Feardoor.
  3. (Windows 95/98/Me only) Remove the lines that the Trojan added to the Win.ini and Autoexec.bat files.

For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions 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 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.

To scan for and delete the infected files:
  1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
  2. Run a full system scan.
  3. If any files are detected as infected with Backdoor.Feardoor, click Delete.

To remove the lines that the Trojan added to the Win.ini and Autoexec.bat files:

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 these lines:

    load=\Windows\System32\Directx\DxDiag.exe
    open=\Windows\System32\Directx\DxDiag.exe

  4. For each of the lines that exists, 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.
  7. Click Start, and click Run.
  8. Type the following, and then click OK.

    edit c:\autoexec.bat

    The MS-DOS Editor opens.
  9. Look for the line

    Windows\System32\Directx\DxDiag.exe
  10. If it exists, delete it.
  11. Click File, and click Save.
  12. Click File, and click Exit.


Writeup By: Kaoru Hayashi

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