Discovered: August 15, 2005
Updated: February 13, 2007 12:43:25 PM
Also Known As: CME-354, Win32.Esbot.{A, B} [Computer Associates], Backdoor.Win32.IRCBot.es [Kasp, W32/IRCbot.gen [McAfee], W32/Sdbot-ACG [Sophos], BKDR_RBOT.BD [Trend Micro]
Type: Worm
Systems Affected: Windows



W32.Esbot.A is a worm that spreads by exploiting the Microsoft Windows Plug and Play Buffer Overflow Vulnerability (described in Microsoft Security Bulletin MS05-039 ).

Note:

  • Customers running Norton Internet Security 2005 AntiSpyware Edition and Symantec AntiVirus Corporate Edition 10.x can make use of the product's remediation functionality to remove this risk.
  • While computers running Windows 95/98/Me/NT4/XP operating systems cannot be infected remotely, it is possible they could be infected if the threat is executed locally (although this is an unlikely occurrence). Vulnerable Windows 2000 computers could then be infected by the compromised computer.


Antivirus Protection Dates

  • Initial Rapid Release version August 15, 2005
  • Latest Rapid Release version September 13, 2018 revision 003
  • Initial Daily Certified version August 15, 2005
  • Latest Daily Certified version September 13, 2018 revision 005
  • Initial Weekly Certified release date August 15, 2005

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

Writeup By: Yana Liu

Discovered: August 15, 2005
Updated: February 13, 2007 12:43:25 PM
Also Known As: CME-354, Win32.Esbot.{A, B} [Computer Associates], Backdoor.Win32.IRCBot.es [Kasp, W32/IRCbot.gen [McAfee], W32/Sdbot-ACG [Sophos], BKDR_RBOT.BD [Trend Micro]
Type: Worm
Systems Affected: Windows


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

  1. Creates the following mutexes so that only one copy of the worm runs on the compromised computer:

    • mousebm
    • mousemm
    • mousesync

  2. Copies itself as one of the following:

    • %System%\mousebm.exe
    • %System%\mousemm.exe
    • %System%\mousesync.exe

      Note: %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  3. Runs itself as one of the following services:

    Service Name: mousebm
    Display Name: Mouse Button Monitor
    Description: Enables a computer to maintain synchronization with a PS/2 pointing device. Stopping or disabling this service will result in system instability.
    Path to executable: %System%\mousebm.exe

    Service Name: mousemm
    Display Name: Mouse Movement Monitor
    Description: Enables a computer to maintain synchronization with a PS/2 pointing device. Stopping or disabling this service will result in system instability.
    Path to executable: %System%\mousemm.exe

    Service Name: mousesync.exe
    Display Name: Mouse Synchronization
    Description: Enables a computer to maintain synchronization with a PS/2 pointing device. Stopping or disabling this service will result in system instability.
    Path to executable: %System%\mousesync.exe

  4. Adds one of the following values:

    "%System%\mousebm.exe"
    "%System%\mousemm.exe"
    "%System%\mousesync.exe"

    in the registry subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

    depending on which of the above services are created.

  5. Injects itself into explorer.exe.

  6. Modifies the value:

    "EnableDCOM" = "N"

    in the registry subkey:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Ole

    to disable DCOM.

  7. Adds the value:

    "restrictanonymous" = "1"

    to the registry subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

    to restrict anonymous access to network shares.

  8. Creates the following empty read-only file:

    %Windir%\debug\dcpromo.log

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

  9. Attempts to connect to one of the following IRC servers on TCP port 18067 to listen for IRC commands:

    • esxt.is-a-fag.net
    • esxt.legi0n.net

  10. IRC commands allow the attacker to perform the following actions:

    • Download and execute files
    • List, stop, and start processes and threads
    • Launch denial of service attacks
    • Find files on local hard disks
    • Scan for computers and attempts to exploit the Microsoft Windows Plug and Play Buffer Overflow Vulnerability (described in Microsoft Security Bulletin MS05-039). If successful, the worm sends shell code to the remote machine and transfers a copy of itself.


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 15, 2005
Updated: February 13, 2007 12:43:25 PM
Also Known As: CME-354, Win32.Esbot.{A, B} [Computer Associates], Backdoor.Win32.IRCBot.es [Kasp, W32/IRCbot.gen [McAfee], W32/Sdbot-ACG [Sophos], BKDR_RBOT.BD [Trend Micro]
Type: Worm
Systems Affected: Windows


Removal using the W32.Esbot Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Esbot.A. Use this removal tool first, as it is the easiest way to remove this threat.

Manual Removal:

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. Find and stop the service.
  4. Run a full system scan and delete all the files detected.
  5. 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:
Note:
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 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 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 find and stop the service
  1. Click Start > Run.
  2. Type services.msc, and then click OK.
  3. Locate and select any of the following services present:

    • Mouse Button Monitor
    • Mouse Movement Monitor
    • Mouse Synchronization

  4. Click Action > Properties.
  5. Click Stop.
  6. Change Startup Type to Manual.
  7. Click OK and close the Services window.
  8. Restart the computer.
4. 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, click Delete.

Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do 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 the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and 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.


5. 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.

    Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.

  4. Navigate to the subkey:

    HKEY_LOCAL_MACHINE\Software\Microsoft\OLE

  5. In the right pane, reset the following value to its original setting (if applicable):

    "EnableDCOM"

  6. Navigate to the subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

  7. In the right pane, reset the following value to its original setting (if applicable):

    "restrictanonymous"

  8. Exit the Registry Editor.


Writeup By: Yana Liu