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Discovered: April 05, 2005
Updated: February 13, 2007 12:36:29 PM
Type: Virus
Systems Affected: Windows

W32.Dreffort is a file infector of .EXE and .SCR files with back door capabilities.

Antivirus Protection Dates

  • Initial Rapid Release version April 06, 2005
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version April 06, 2005
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date April 06, 2005

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

Writeup By: Peter Ferrie

Discovered: April 05, 2005
Updated: February 13, 2007 12:36:29 PM
Type: Virus
Systems Affected: Windows

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

  1. Infects all .EXE and .SCR files in all subdirectories on drives C - Z.

  2. Adds itself to .RAR archives.

  3. Deletes any files that it can find on the 29th of December in any year.

  4. Drops a back door that binds a command-shell on TCP port 666 on the 29th of any month.

  5. Has a random filename for the back door.

  6. Adds the value using the back door component:

    "Voltage Manager" = "[random file name]"

    to the registry subkey:


  7. Disables the Windows Firewall.

  8. Intends to send itself by email, but this functionality does not work on Windows XP or 2003.
    Message body is one of the following:

    • Dear Microsoft Customer

      A new vulnerability has been discovered in Internet Explorer
      we recommending you to update internet explorer as soon as
      possible, this vulnerablility is critical and may allow
      execution of malicious code on your system while you use internet

    • 150 XXX Pictures For You !!!

      here are your dayly xxx pictures.
      Have Fun & Enjoy...

      we like to inform you that your account at
      our web site will be expired at the end of
      this month,please renew your account
      renew of account for old members is only 25$
      per half year.

      Please Visit Our Web Site:

    • Dear Symantec/F-Secure/Mcafee/Trend Micro User

      We Have Developed A New Tool That Can Block New
      Internet Worms From Attacking Your Computer,We
      Recommending To Install This Tool Before A New
      Internet Worm Will Start To Spread

      How To Use The Tool:
      Just Run The Attached File,After You Have Run It
      Follow The Instructions.

      Thank You.
      The Virus Bulletin Security Team.
      For More Information Please Visit Our Web Site:

      If you do not wish to receive future antivirus tools from
      Virus Bulletin, or believe you were subscribed in error,
      please send,a blank E-mail to Subscribe@Virusbtn.com

    • Dear User.

      Sharman Networks Wants To offer You The New
      Version Of Kazaa !!!
      Please Read Product Description Below:

      Kazaa Media Desktop is the world's No. 1
      free, peer-to-peer, file-sharing software
      application. Features include improved
      privacy protection; the ability to search
      for and download music, playlists, software,
      video files, documents, and images; the
      ability to set up and manage music and video
      playlists; and the ability to perform
      multiple simultaneous searches, including
      up to five Search Mores, which deliver up
      to 1,000 results per search term.

      We Have Included A Free Version Of Kazaa In
      This Mail,Try It !!!

      Thank You.
      Sharman Networks.

      If you do not wish to receive future E-mail's from
      Sharman Networks, or believe you were subscribed in
      error, please send a blank E-mail to Remove@kazaa.com

    • Greeting-Cards.com have sent you a Greeting Card

      One Of Your Friends Wish You Happy Year
      Love,Fun,Good Life,And Good Luck.

      To Show His Love He Sent You A Greeting
      Card,Congratulations !

      Hope you enjoy our e-cards! Spread the love and send one of our FREE e-cards!
      Brought to you by greeting-cards.com - a better way to greet for FREE!
      Please Visit Greeting Cards Web site:http://www.greeting-cards.com/


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: Peter Ferrie

Discovered: April 05, 2005
Updated: February 13, 2007 12:36:29 PM
Type: Virus
Systems Affected: Windows

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.Dreffort.
    4. Delete any values added to the registry.
    For specific details on each of these steps, read the following instructions.

    1. To disable 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:
    When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable System Restore by following the instructions in the aforementioned documents.

    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. To update 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 document: Virus Definitions (LiveUpdate).
      • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. 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 document: Virus Definitions (Intelligent Updater).

        The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions. For detailed instructions read the document: How to update virus definition files using the Intelligent Updater.

    3. To scan for and delete the infected files
    1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
    2. Run a full system scan.
    3. If any files are detected as infected with W32.Dreffort, click Delete.

      If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix this, run the scan in Safe mode. For instructions, read the document: How to start the computer in Safe Mode. Once you have restarted in Safe mode, run the scan again.

      After the files are deleted, restart the computer in Normal mode and proceed with section 4.

      Warning messages may be displayed when the computer is restarted, as the threat has not been fully removed at this point. Please ignore these messages and just click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

      Title: [File path]
      Message body: Windows cannot find [file name]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.

    4. To delete the value from the registry
    Important: 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 subkeys only. For instructions refer to the document: How to make a backup of the Windows registry.
    1. Click Start > Run.

    2. Type regedit

    3. Click OK.

    4. Navigate to the subkey:


    5. In the right pane, delete the value:

      "Voltage Manager" = "[randome file name]"

    6. Exit the Registry Editor.

    5. To restore the Windows Security Center
    This threat attempts to disable the features in the Windows Security Center. If you are running Windows XP and would like to restore the full functionality of the Windows Security Center, please complete the following steps:

    Important: If your computer is connected to a domain, you may not be able to adjust these settings. If so, contact your network administrator for more information.
    1. Click Start > Control Panel.
    2. Double-click the Security Center.
    3. In the right pane, click Windows Firewall. The Windows Firewall appears.
    4. Select On.
    5. Click OK to close the Windows Firewall.
    6. In the left pane of the Security Center, select Change the way Security Center alerts me.
    7. Click Alert Settings.
    8. Select Alert Settings, Firewall, and Virus Protection.
    9. Click OK
    10. Click Automatic Updates.
    11. Select Automatic.
    12. Click OK.
    13. Exit the Security Center.

    Writeup By: Peter Ferrie