W32.Dinfor.Worm

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Discovered: February 06, 2004
Updated: February 13, 2007 12:17:07 PM
Also Known As: WORM_SDBOT.FP [Trend]
Type: Worm
Systems Affected: Windows



W32.Dinfor.Worm is a worm that spreads across network shares. It exploits weak passwords and uses the DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-039 ) to create user accounts on remote computers. This worm also acts as a backdoor, connecting to an IRC channel and allowing a remote attacker to control an infected computer.

Antivirus Protection Dates

  • Initial Rapid Release version February 06, 2004
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version February 06, 2004
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date February 09, 2004

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

Writeup By: Fergal Ladley

Discovered: February 06, 2004
Updated: February 13, 2007 12:17:07 PM
Also Known As: WORM_SDBOT.FP [Trend]
Type: Worm
Systems Affected: Windows


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

  1. Copies itself as the following files:
    • %System%\Spoolserv.exe
    • %System%\Cmst32.exe
    • %Temp%\d.bat: A malicious batch file detected as W32.Dinfor.Worm.
    • %System%\Pctime32.bat: A malicious batch file detected as W32.Dinfor.Worm.
    • %System%\Runtime.bat: A malicious batch file detected as W32.Dinfor.Worm.
    • %System%\Smshost.exe: A hacktool for exploiting the DCOM RPC vulnerability, described in Microsoft Security Bulletin MS03-039. This is detected as Hacktool.Dase. Also, this file is likely to be infected with W32.Pinfi.
    • %System%\Svhost32.exe. A legitimate utility named PsExec, which has been packed with UPX. Since this file is not malicious, Symantec antivirus products do not detect it.


      Notes:
    • %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).
    • %Temp% is a variable: The worm locates the temporary folder and copies itself to that location. By default, this is C:\Windows\TEMP (Windows 95/98/Me), C:\WINNT\Temp (Windows NT/2000), or C:\Document and Settings\<UserName>\Local Settings\Temp (Windows XP).


  2. Adds the value:

    "Microsoft DirectX"="Spoolserv.exe"

    to the registry keys:
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
      RunServices

      so that the worm runs when you start Windows.

  3. Sets the value:

    "restrictanonymous" = "1"

    in the registry key:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa

  4. Sets the value:

    "EnableDCOM" = "N"

    in the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole

  5. Uses the files Runtime.Bat and Pctime32.bat to spread itself to computers on the same network. Runtime.bat attempts to exploit weak username/password combinations, while Pctime32.bat uses Hacktool.Dase to exploit the DCOM RPC vulnerability. Both files will try to copy the worm as Cmst32.exe into the following folders on the remote computer:
    • \Documents and Settings\All Users\Menu Demarrer\Programmes\Demarrage
    • \WINNT\Start Menu\Programs\Startup
    • \WIN\Start Menu\Programs\Startup
    • \Documents and Settings\All Users\Start-meny\Program\Autostart
    • \Documents and Settings\All Users\Menu Start\Programma's\Opstarten
    • \WINDOWS\All Users\Start Menu\Programs\StartUp
    • \WINNT\All Users\Start Menu\Programs\Startup
    • \WINNT\Profiles\All Users\Start Menu\Programs\Startup
    • \WINDOWS\Start Menu\Programs\Startup
    • \Documenti e Impostazioni\All Users\Start Menu\Programs\Startup
    • \Dokumente und Einstellungen\All Users\Start Menu\Programs\Startup
    • \Documents and Settings\All Users\Start Menu\Programs\Startup

  6. Issues the following commands:

    net stop navapsvc /y
    net stop "RA Server"
    net stop firedaemon
    net stop McShield
    net stop "WMDM PMSP Service"
    net stop AVPCC /y
    net stop PERSFW /y
    net stop "Remote Access Connection Manager"
    net stop "REMOTE PROCEDURE CALL SERVICE"
    net stop "REMOTE PROCEDURE CALL"
    net share /delete IPC$ /y
    net share /delete ADMIN$ /y
    net share /delete C$ /y
    net share D$ /delete
    net share C$ /delete
    net share netbios /delete
    stop systask
    stop PSEXESVC
    net share /del osucum$ /y
    net share /del IPC$ /y
    net share /del e$ /y
    net share /del d$ /y
    net share /del C$ /y
    net share /del admin$
    net user e /del
    net stop netbios /y
    net stop "Nav Auto-Protect" /y
    net stop "NAV Alert" /y
    net stop "Norton AntiVirus Server" /y
    net stop "Norton AntiVirus Client" /y
    net stop "Symantec AntiVirus Client" /y
    net stop "Norton AntiVirus Auto Protect Service" /y

  7. Attempts to delete the following files:
    • C:\Program Files\Norton AntiVirus\navapsvc.exe
    • D:\Program Files\Norton AntiVirus\navapsvc.exe
    • C:\Program Files\Symantec\LiveUpdate\AUPDATE.EXE
    • D:\Program Files\Symantec\LiveUpdate\AUPDATE.EXE

  8. Joins an IRC channel and waits for commands from a remote attacker. The attacker can:
    • Retrieve information about the infected host, such as the operating system version and the computer's hardware
    • Upload and download files
    • Execute files
    • Use the computer to perform Denial of Service (DoS) attacks on other computers


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: Fergal Ladley

Discovered: February 06, 2004
Updated: February 13, 2007 12:17:07 PM
Also Known As: WORM_SDBOT.FP [Trend]
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.Dinfor.Worm.
  4. Delete the value that was added to the registry.
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:
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. 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.Dinfor.Worm, click Delete.

4. Deleting the value from 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:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

  4. In the right pane, delete the value:

    "Microsoft DirectX"="SpoolServ.exe"

  5. Navigate to the key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
    RunServices

  6. In the right pane, delete the value:

    "Microsoft DirectX"="SpoolServ.exe"

  7. The following step is optional as this key may already have manually been set to the value of "1" prior to any infection. Navigate to the key:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa

  8. In the right pane, set the DWORD value:

    "restrictanonymous" = "0"

  9. The following step is optional as this key may already have manually been set to the value of "N" prior to any infection. Navigate to the key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole

  10. In the right pane, set the value:

    "EnableDCOM" = "Y"

    to the correct value.

  11. Exit the Registry Editor.


Writeup By: Fergal Ladley