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Discovered: January 25, 2004
Updated: February 13, 2007 12:16:38 PM
Also Known As: W32/Dumaru.z@MM [McAfee], Win32.Dumaru.Z [Computer Assoc, I-Worm.Dumaru.l [Kaspersky], WORM_DUMARU.Z [Trend]
Type: Worm
Systems Affected: Windows

W32.Dumaru.Z@mm is a multi-threaded, mass-mailing worm that downloads and runs a file, runs a keylogger, and attempts to steal personal information. This worm is similar to the W32.Dumaru.Y@mm worm.

The email has the following characteristics:

From:  "Elene" <F**KENSUICIDE@HOTMAIL.COM> (censored)
Subject: Important information for you. Read it immediately !
Attachment: Myphoto.zip

The attachment is a zip file that contains the worm executable as myphoto.jpg  <spaces> .exe". (There are numerous spaces between ".jpg" and ".exe".)

A large number of email messages were sent purporting to be from Microsoft, with a link to a Web page. This email exploits a bug in Microsoft Internet Explorer so that, although the link appears to be to www.microsoft.com, it is actually a link to a Web page that contains a Visual Basic script, which drops W32.Dumaru.Z@mm onto your computer under the name C:\2.exe.

The email that was sent is an HTML email message with the following characteristics -

Note : This is not the email that the worm sent itself, but it is rather an email sent to deceive people into downloading the worm:

From:  "Security-center" [security-center@microsoft.com]
Subject: Security warning
Message: MicroSoft News
Warning: a new virus, W32.Swen.A@mm, can infect your computer.

MicroSoft user,
this is the latest version of security update, the "January 2004, Cumulative Patch" udate which eliminates all known security vulnerabilities afecting MS Internet Explorer, MS Outlook and MS Outlook Express. Install now to maintain the security of your computer from these vulnerabilities. This update includes the functionality of all previously released patches.

[text omitted]

[end of email text].

The message includes two links named "Go to Download page."

Antivirus Protection Dates

  • Initial Rapid Release version January 26, 2004
  • Latest Rapid Release version October 25, 2017 revision 035
  • Initial Daily Certified version January 26, 2004
  • Latest Daily Certified version October 26, 2017 revision 003
  • Initial Weekly Certified release date January 26, 2004

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

Technical Description

When W32.Dumaru.Z@mm is executed, it performs the following actions:

    1. Deletes the file, C:\2.exe. This file is a copy of the worm, which is Web page drops (See the Short Description).

    2. Copies itself as the following files:
      • %System%\L32x.exe
      • %System%\Vxd32v.exe
      • %Startup%\Dllxw.exe
      • %Windir%\Temp\Zip.tmp

        • %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
        • %Startup% is a variable: The worm locates the Windows startup folder and copies itself to that location. For example, this is C:\Windows\Start Menu\Programs\Startup in the Windows 98 system.
        • %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.

    3. Creates the following files:
      • %Windir%\Winload.log: This file is used to store the email addresses that the worm finds. It sends itself to these addresses.
      • %Windir%\Vxdload.log: This file is used to store passwords and other information, which the user types.
      • %Windir%\Rundllx.sys: This file stores data that is pasted to the clipboard.

    4. Adds the value:


      to the registry key:


      so that the worm runs when you start Windows.

    5. Modifies the [boot] section of the System.ini file (Windows 95/98/Me only) as follows:

      shell=explorer.exe %System%\vxd32v.exe

    6. Modifies the value:


      in the registry key:

      HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon




      "explorer.exe %Windir%\system32\vxd32v.exe"

      so that the worm runs when you start Windows NT/2000/XP.

    7. May create the subkey:


      in the registry key


    8. If the value:


      is set to 0 in the registry key:


      then the worm attempts to download a file from a URL that is hard-coded into the worm, save it as %System%\Nvidia32.exe, and then execute it. At the time of writing, Symantec antivirus products detected the downloaded file as W32.Spybot.Worm.

      Then, it sets the value:


      in the registry key:


    9. Monitors the clipboard and stores the data pasted to the clipboard in the file, %Windir%\Rundllx.sys.

    10. Captures keystrokes entered into windows, with the title "https:/ /www.e-gold.com/srk.asp - Microsoft Internet Explorer," and then stores them in the file, %Windir%\Vxdload.log.

    11. Periodically emails the contents of Winload.log, Vxdload.log, and Rundllx.sys to an email address that is hardcoded in the worm.

    12. Searches the C drive for the files with the following extensions:
      • .htm
      • .wab
      • .html
      • .dbx
      • .tbb
      • .abd

        and saves any email addresses it finds in such files to the file, %Windir%\Winload.log.

    13. Sends an email to each address in the file, %Windir%\Winload.log, with itself as an attachment.

      The email has the following characteristics:

      From: "Elene" <F**KENSUICIDE@HOTMAIL.COM> (censored)
      Subject: Important information for you. Read it immediately !
      Hi !
      Here is my photo, that you asked for yesterday.
      Attachment: myphoto.zip


    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.


    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. Do one of the following:
      • Windows 95/98/Me: Restart the computer in Safe mode.
      • Windows NT/2000/XP: End the malicious process.
    4. Run a full system scan and delete all the files detected as W32.Dumaru.Z@mm.
    5. Reverse the changes made to the registry.
    6. Edit the System.ini file (Windows 95/98/Me).
    For details on each of these steps, read the following instructions.

    1. Disabling 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. Updating 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 on U.S. business days (Monday through Friday). 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 Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

    3. Restarting the computer in Safe mode or ending the malicious process
      Windows 95/98/Me
      Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."

      Windows NT/2000/XP
      To end the malicious process:
      1. Press Ctrl+Alt+Delete once.
      2. Click Task Manager.
      3. Click the Processes tab.
      4. Double-click the Image Name column header to alphabetically sort the processes.
      5. Scroll through the list and look for "vxd32v.exe," "l32x.exe," or "dllxw.exe."
      6. If you find one of these files, click it, and then click End Process.
      7. Exit the Task Manager.
    4. Scanning for and deleting 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.Dumaru.Z@mm, click Delete.

    5. Reversing the changes made to the registry

    WARNING: 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 keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
    1. Click Start, and then click Run. (The Run dialog box appears.)
    2. Type regedit

      Then click OK. (The Registry Editor opens.)

    3. Navigate to the key:


    4. In the right pane, delete the value:


    5. Do one of the following:
      • If you are using Windows 95/98/Me, proceed to step i.
      • If you are using Windows NT/2000/XP, proceed to step f.

    6. Navigate to the key:

      HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon

    7. In the right pane, double-click: Shell

    8. Change:

      "explorer.exe %Windir%\system32\vxd32v.exe"



    9. Navigate to the key:


    10. If the subkey:


      exists, delete it.

    11. Exit the Registry Editor.

    12. Restart the computer back into Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."

    6. Editing the System.ini file
    If you are running Windows 95/98/Me, follow these steps:
    1. The function you perform depends on your operating system:
      • Windows 95/98: Go to step B.
      • Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made a backup copy of the System.ini file that you need to edit. If this backup copy exists, it will be in the C:\Windows\Recent folder. Symantec recommends that you delete this file before continuing with the steps in this section. To do this:
        1. Start Windows Explorer.
        2. Browse to and select the C:\Windows\Recent folder.
        3. In the right pane, select the System.ini file and delete it. The System.ini file will be regenerated when you save your changes to it in step F.

    2. Click Start, and then click Run.

    3. Type the following, and then click OK.

      edit c:\windows\system.ini

      (The MS-DOS Editor opens.)

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

    4. In the [boot] section of the file, look for a line similar to:

      shell = Explorer.exe C:\WINDOWS\SYSTEM\vxd32v.exe

    5. If this line exists, delete everything to the right of Explorer.exe.

      When you are done, it should look like:

      shell = Explorer.exe

    6. Click File, and then click Save.

    7. Click File, and then click Exit.

    Writeup By: Fergal Ladley