W32.Dumaru@mm

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Discovered: August 16, 2003
Updated: February 13, 2007 12:05:36 PM
Also Known As: PE_DUMARU.A [Trend], Win32.Dumaru [Computer Associa, W32/Dumaru@MM [McAfee], W32/Dumaru-A [Sophos], I-Worm.Dumaru [Kaspersky]
Type: Worm
Systems Affected: Windows


W32.Dumaru@mm is a mass-mailing worm that drops an IRC Trojan onto an infected machine. The worm gathers email addresses from certain file types and uses its own SMTP engine to email itself.

The email has the following characteristics:

From: "Microsoft" <security@microsoft.com>
Subject: Use this patch immediately !
Message:
Dear friend , use this Internet Explorer patch now!
There are dangerous virus in the Internet now!
More than 500.000 already infected!
Attachment: patch.exe

The worm will also infect the exe files on NTFS partitions.

This threat is compressed with UPX.

Antivirus Protection Dates

  • Initial Rapid Release version August 18, 2003
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version August 18, 2003
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date August 18, 2003

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

Writeup By: Yana Liu

Discovered: August 16, 2003
Updated: February 13, 2007 12:05:36 PM
Also Known As: PE_DUMARU.A [Trend], Win32.Dumaru [Computer Associa, W32/Dumaru@MM [McAfee], W32/Dumaru-A [Sophos], I-Worm.Dumaru [Kaspersky]
Type: Worm
Systems Affected: Windows


When W32.Dumaru@mm is executed, it does the following:

  1. Copies itself as the following:

    %Windir%\dllreg.exe
    %System%\load32.exe
    %System%\vxdmgr32.exe

    NOTES:
    • %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.
    • %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).

  2. Creates %Windir%\windrv.exe (8,192 bytes), which is an IRC Trojan. When run, it connects to a predefined IRC server and joins a specific channel to listen for commands from the worm's creator.

  3. Creates %Windir%\winload.log, which is a log file. The worm uses this file to store the stolen email addresses.

    NOTE: This file is not viral by itself, and therefore, Symantec antivirus products do not detect this file. Manually delete it if your system is infected with this worm.

  4. Adds the value:

    "load32" = "%Windir%\load32.exe"

    to the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    so that the worm runs when you start Windows.

  5. Adds the value (Windows NT/2000/XP only):

    "Run" = "C:\%Windir%\dllreg.exe"

    to the registry key:

    HKEY_Current_User\Software\Microsoft\WindowsNT\CurrentVersion\
    Windows

  6. Adds one of the values (Windows NT/2000/XP only):
    • "Shell" = "C:\%Windir%\dllreg.exe"
    • "Shell" = "C:\%System%\load32.exe"
    • "Shell" = "C:\%System%\Vxdmgr32.exe"

      to the registry key:

      HKEY_Local_Machine\Software\Microsoft\WindowsNT\CurrentVersion\
      Winlogon

  7. Modifies the windows section of the win.ini file (Windows 95/98/Me only):

    [windows]
    run=%Windir%\dllreg.exe

  8. Modifies the boot section of system.ini file (Windows 95/98/Me only):

    [boot]
    shell=explorer.exe %System%\vxdmgr32.exe

  9. Retrieves email addresses from the files with the following extensions:

    .htm
    .wab
    .html
    .dbx
    .tbb
    .abd

  10. Uses its own SMTP engine to email itself.

    The email has the following characteristics:

    From: "Microsoft" <security@microsoft.com>
    Subject: Use this patch immediately !
    Message:
    Dear friend , use this Internet Explorer patch now!
    There are dangerous virus in the Internet now!
    More than 500.000 already infected!
    Attachment: patch.exe

  11. Infects the exe files on NTFS partitions in the following way:

    Copies the original file to the stream, <original filename>:STR.
    Overwrites the original filename with the worm.

    NOTE: Explorer will be unable to display the original file, as it is contained within a stream.

  12. The worm attempts to infect all the exe files on drives C-Z; however, due to bugs in the code, it will only infect files in the root directory of all drives C-Z.



Symantec Gateway Security
On August 18, 2003, Symantec released an update for Symantec Gateway Security 1.0.

Symantec Host IDS
On August 19, 2003, Symantec released an update for Symantec Host IDS 4.1.

Intruder Alert
On August 19, 2003, Symantec released Intruder Alert 3.6 W32_Dumaru_Worm Policy .

Symantec ManHunt
Security Update 7 has been released to provide signatures that are specific to W32.Dumaru@mm.

Symantec Client Security
On August 20, 2003, Symantec released IDS signatures via LiveUpdate to detect W32.Dumaru@mm activity.

Norton Internet Security / Norton Internet Security Professional
On August 20, 2003, Symantec released IDS signatures via LiveUpdate to detect W32.Dumaru@mm activity.

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: Yana Liu

Discovered: August 16, 2003
Updated: February 13, 2007 12:05:36 PM
Also Known As: PE_DUMARU.A [Trend], Win32.Dumaru [Computer Associa, W32/Dumaru@MM [McAfee], W32/Dumaru-A [Sophos], I-Worm.Dumaru [Kaspersky]
Type: Worm
Systems Affected: Windows


Removal using the W32.Dumaru@mm Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Dumaru@mm. This is the easiest way to remove this threat and should be tried first. To obtain the W32.Dumaru@mm removal tool, read the document, "W32.Dumaru Removal Tool ."

Manual Removal
As an alternative to using the removal tool, you can manually remove this threat. 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.Dumaru@mm or IRC Trojan. Restore all the exe files in the root directory of all drives C-Z from Backup copies.
  4. Delete the value that was added to the registry.
  5. Remove the lines that the worm added to the Win.ini or System.ini files (Windows 95/98/Me).
For specific 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:
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. 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@mm or IRC Trojan, click Delete.
  4. For all exe files in the root directory of all drives that are deleted, restore these files from backup copies.

4. Deleting the value from the registry

CAUTION : 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:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

  4. In the right pane, delete the value:

    "load32"="%Windir%\load32.exe"

  5. Exit the Registry Editor.



5. Removing the lines added to the Win.ini or System.ini files (Windows 95/98/Me only)
If you are running Windows 95/98/Me, follow these steps:

The function you perform depends on your operating system:
    • Windows 95/98:
      1. Click Start, and then 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 a line similar to:

        run=%Windir%\dllreg.exe

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

        When you are done, it should look like: run=

      5. Click File, and then click Save.

      6. Click File, and then click Exit.

      7. Click Start, and then click Run.

      8. 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.

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

        shell = explorer.exe  %Windir%\vxdmgr32.exe

      10. If this line exists, delete everything to the right of explorer.exe.

        When you are done, it should look like:

        shell = explorer.exe

      11. Click File, and then click Save.

      12. Click File, and then click Exit.

    • Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made a backup copy of the Win.ini or system.ini files that you need to edit. If the backup copies exist, they will be in the C:\Windows\Recent folder. Symantec recommends that you delete the backup files 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 Win.ini file and delete it. The Win.ini file will be regenerated when you restart your computer.
      4. In the right pane, select the System.ini file and delete it. The System.ini file will be regenerated when you restart your computer.



Writeup By: Yana Liu