Backdoor.Feardoor

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Discovered: October 08, 2002
Updated: February 13, 2007 11:59:16 AM
Also Known As: Backdoor.Feardoor.161 [AVP]
Type: Trojan Horse
Systems Affected: Windows


Backdoor.Feardoor is a backdoor Trojan that allows a hacker to remotely control an infected computer. It is written in the Microsoft Visual Basic version 6 programming language.

The backdoor opens four ports by default: 1218, 1219, 2000, and 6697

Antivirus Protection Dates

  • Initial Rapid Release version October 08, 2002
  • Latest Rapid Release version November 05, 2017 revision 037
  • Initial Daily Certified version October 08, 2002 revision 036
  • Latest Daily Certified version November 06, 2017 revision 009
  • Initial Weekly Certified release date October 09, 2002

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Kaoru Hayashi

Discovered: October 08, 2002
Updated: February 13, 2007 11:59:16 AM
Also Known As: Backdoor.Feardoor.161 [AVP]
Type: Trojan Horse
Systems Affected: Windows


When Backdoor.Feardoor runs, it does the following:

It copies itself as \Windows\System32\Directx\DxDiag.exe. This path is hard-coded, and the file is not copied if the path and folder structure does not exist.

NOTE: The copy of the file DxDiag.exe that the Trojan drops is not the same as the legitimate Microsoft file of the same name. The legitimate file, which is a DirectX diagnostic tool, is located by default in the %system% folder, not in the \Directx subfolder.

The Trojan adds these lines

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

to the Win.ini file

and the line

\Windows\System32\Directx\DxDiag.exe

to the Autoexec.bat file.

As a result, on Windows 95/98/Me-based computers, the Trojan runs each time that you start Windows.

The Trojan drops Visual Basic runtime libraries (such as Mswinsck.ocx and Msinet.ocx) into the %system% folder. These files are not infected and therefore are not detected by Symantec antivirus products.

It opens four ports by default: 1218, 1219, 2000, and 6697.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Kaoru Hayashi

Discovered: October 08, 2002
Updated: February 13, 2007 11:59:16 AM
Also Known As: Backdoor.Feardoor.161 [AVP]
Type: Trojan Horse
Systems Affected: Windows


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