Discovered: February 25, 2005
Updated: February 13, 2007 12:34:16 PM
Type: Worm
Systems Affected: Windows


W32.Refaz is a worm that propagates through file-sharing networks and network shares. The worm also modifies certain .HTML files on the compromised computer.

Antivirus Protection Dates

  • Initial Rapid Release version February 25, 2005
  • Latest Rapid Release version February 25, 2005
  • Initial Daily Certified version February 25, 2005
  • Latest Daily Certified version February 25, 2005
  • Initial Weekly Certified release date February 27, 2005

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

Writeup By: Kaoru Hayashi

Discovered: February 25, 2005
Updated: February 13, 2007 12:34:16 PM
Type: Worm
Systems Affected: Windows


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

  1. Displays a message with the following text:

    Title:
    BETA VERSION

    Message:
    Version limited time expired.



  2. Copies itself as the following files:

    • %Windir%\winshell.exe
    • %Windir%\win_3k.exe
    • %Windir%\Zafer.exe
    • a:\ForYou.pif
    • C:\inetpub\wwwroot\xradiat.exe

      Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.

  3. Creates the following files:

    • C:\url.vxd
    • C:\Zafer.scr

  4. Creates further copies of itself. The name of the file is chosen by randomly selecting from the following list and adding an .exe extension:

    • Ad-Aware 6.0
    • Spybot 1.3
    • Icq 4
    • WinZip 9.
    • Imesh
    • LimeWire
    • Morpheus
    • Avant Browser
    • Icq Pro 003b
    • RealPlayer
    • DivX Player (with DivX Codec)
    • Download Accelerator Plus
    • WinRAR
    • MSN Toolbar
    • Trillian Messenger
    • Warez peer to peer
    • Registry Mechanic
    • Adobe Acrobat Reader
    • Spyware Doctor
    • VirtualLab Data Recovery
    • Ares Galaxy
    • Yahoo Messenger
    • NetPumper
    • ZoneAlarm
    • FlashGet
    • eMule
    • RoboForm
    • SpyHunter
    • BitComet
    • dBpowerAmp Music Converter
    • HijackThis
    • All-in-One Secretmaker
    • JetAudio Basic
    • Nero 6 Ultra Edition Video Ads Blocker
    • Kazaa Download Accelerator Pro
    • AOL Instant Messenger (AIM)
    • MSN Messenger (Windows XP)
    • QuickTime
    • Bazooka Adware and Spyware Scanner
    • Ad-aware 6 Reference File
    • SolSuite 004 - Solitaire Card Games Suite
    • Microsoft Windows Media Player
    • Webroot Spy Sweeper
    • Norton AntiVirus Definitions Update (i3 Package)
    • WS_FTP LE
    • WinPatrol
    • Winamp Pro 004 Edition
    • Avast Home Edition

      The files are created in the following folders used by file sharing applications:

    • %ProgramFiles%\KaZaA\My Shared Folder
    • %ProgramFiles%\edonkey2000\incoming
    • %ProgramFiles%\gnucleus\downloads
    • %ProgramFiles%\icq\shared files
    • %ProgramFiles%\kazaa lite\My Shared Folder
    • %ProgramFiles%\limewire\shared
    • %ProgramFiles%\morpheus\my shared folder
    • %ProgramFiles%\Grokster\My Grokster
    • %ProgramFiles%\WinMX\My Shared Folder
    • %ProgramFiles%\Tesla\Files
    • %ProgramFiles%\Overnet\Incoming
    • %ProgramFiles%\XoloX\Downloads
    • %ProgramFiles%\Rapigator\Share
    • %ProgramFiles%\KMD\My Shared Folder

      Note: %ProgramFiles% is a variable that refers to the program files folder. By default, this is C:\Program Files.

  5. Modifies the following files:

    • C:\inetpub\wwwroot\index.htm
    • C:\inetpub\wwwroot\index.html
    • C:\inetpub\wwwroot\index.php
    • C:\inetpub\wwwroot\Default.htm
    • C:\inetpub\wwwroot\Default.html
    • C:\inetpub\wwwroot\Default.php

      with the following content:

      Title:
      You need Xradiat

      Body:
      Welcome to our new website!
      to see our new stuff you need Xradiat plugin!
      http: //www.microsoft.com/downloa25ds/xradiat/

      Note: The URL links to a copy of the worm at C:\inetpub\wwwroot\xradiat.exe.

  6. Adds the user Zafer to the administrator group.

  7. Runs the telnet.exe program.

  8. Searches for open network shares on the local network and copies itself as clean_service.cmd to the following folders on the remote computer:

    • \Documents and Settings\All Users\Start Menu
    • \Programs\Startup\WINDOWS\Start Menu
    • \Programs\Startup\WINDOWS\Meninicio
    • \Programas\Inicio\WINNT\Profiles\All Users\Start Menu
    • \Programs\Startup
    • [file sharing application root directory]

  9. Adds the following line to autoexec.bat on the remote computer, so that it is executed when Windows starts:

    @start [path to clean_service.cmd]

  10. Adds the following line to win.ini on the remote computer so that the worm runs when Windows starts:

    run=[path to clean_service.cmd]


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: February 25, 2005
Updated: February 13, 2007 12:34:16 PM
Type: Worm
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.Refaz.
  4. Remove the lines added to the win.ini file.
  5. Remove the lines added to the autoexec.bat file.

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:
Note:
When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable 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 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 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.Refaz, click Delete.

    Note: 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.

    When all the infected files have been deleted, restart the computer in Normal mode.

4. Edit the Win.ini file
If you are running Windows 95/98/Me, follow these steps:
  1. Click Start > Run.
  2. Type the following:

    edit c:\windows\win.ini

    and then click OK.

    (The MS-DOS Editor opens.)

    NOTE: If Windows is installed in a different location, make the appropriate path substitution.

  3. Look for a line similar to:

    run=[path to clean_service.cmd]

  4. If this line exists, delete everything to the right of run=

  5. Click File > Save.
  6. Click File > Exit.

5. Edit the Autoexec.bat file
  1. Click Start > Run.
  2. Type the following:

    edit c:\autoexec.bat

    and then click OK.

    (The MS-DOS Editor opens.)

  3. Look for a line similar to:

    @start [path to clean_service.cmd]

  4. If this line exists, delete it.

  5. Click File > Save.
  6. Click File > Exit.


Writeup By: Kaoru Hayashi