1. Symantec/
  2. Security Response/
  3. W32.Gaobot.BAJ


Risk Level 2: Low

August 2, 2004
February 13, 2007 12:22:25 PM
Systems Affected:

When W32.Gaobot.BAJ is executed, it performs the following actions:
  1. Copies itself to %System%\Wmon32.exe.

    Note: %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. Adds one of the values:


    to the registry keys:


    so that the worm executes every time Windows starts.

  3. Connects to a remote IRC server on port 6667 and listens for commands from the remote attacker, including the following:
    • Download and execute files
    • Scan the network
    • List, stop, and start processes
    • Control the file system (Delete, create, and list files)
    • Launch Denial of Service (DoS) attacks
    • Perform port redirection
    • Steal system information and email it to the attacker

  4. Scans for other computers on the network, attempting to connect to shared resources using a list of user names and passwords. If successful, the worm will attempt to copy itself to the remote computer.

  5. Attempts to propagate to other systems using the following exploits:

    The Microsoft Windows DCOM RPC Interface Buffer Overrun Vulnerability (BID 8205)
    The Microsoft Windows Workstation Service Remote Buffer Overflow Vulnerability (BID 9011)
    The DCOM RPC vulnerability using TCP port 135 (BID 8205)

    The worm uses these exploits to execute itself on the remote system as Winhlpp32.exe.

  6. Scans for computers that the Mydoom variants have infected. If it finds any, it will use the backdoor that Mydoom installed to copy itself onto the computer.

  7. Disables access to certain antivirus Web sites by adding the following lines to %System%\drivers\etc\hosts: www.symantec.com securityresponse.symantec.com symantec.com www.sophos.com sophos.com www.mcafee.com mcafee.com liveupdate.symantecliveupdate.com www.viruslist.com viruslist.com viruslist.com f-secure.com www.f-secure.com kaspersky.com www.avp.com www.kaspersky.com avp.com www.networkassociates.com networkassociates.com www.ca.com ca.com mast.mcafee.com my-etrust.com www.my-etrust.com download.mcafee.com dispatch.mcafee.com secure.nai.com nai.com www.nai.com update.symantec.com updates.symantec.com us.mcafee.com liveupdate.symantec.com customer.symantec.com rads.mcafee.com trendmicro.com www.trendmicro.com

  8. Steals the CD keys of the following computer games:
    • Command & Conquer Generals
    • FIFA 2003
    • Need For Speed Hot Pursuit 2
    • Soldier of Fortune II - Double Helix
    • Neverwinter
    • Rainbow Six III RavenShield
    • Battlefield 1942 Road To Rome
    • Project IGI 2
    • Counter-Strike
    • Unreal Tournament 2003
    • Half-Life


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
Summary| Technical Details| Removal

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