W32.Gaobot.BAJ

Risk Level 2: Low

Discovered:
August 2, 2004
Updated:
February 13, 2007 12:22:25 PM
Type:
Worm
Systems Affected:
Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP

SUMMARY


W32.Gaobot.BAJ is a worm that spreads through open network shares and through backdoors that the Mydoom family of worms open. It allows attackers to access an infected computer using a predetermined IRC channel.

Antivirus Protection Dates

  • Initial Rapid Release version August 2, 2004
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version August 2, 2004
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date August 4, 2004
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Threat Assessment

Wild

  • Wild Level: Low
  • Number of Infections: 0 - 49
  • Number of Sites: 0 - 2
  • Geographical Distribution: Low
  • Threat Containment: Easy
  • Removal: Easy

Damage

  • Damage Level: Medium

Distribution

  • Distribution Level: Medium

TECHNICAL DETAILS


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:

    "WSAConfiguration"="wmon32.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 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:

    127.0.0.1 www.symantec.com
    127.0.0.1 securityresponse.symantec.com
    127.0.0.1 symantec.com
    127.0.0.1 www.sophos.com
    127.0.0.1 sophos.com
    127.0.0.1 www.mcafee.com
    127.0.0.1 mcafee.com
    127.0.0.1 liveupdate.symantecliveupdate.com
    127.0.0.1 www.viruslist.com
    127.0.0.1 viruslist.com
    127.0.0.1 viruslist.com
    127.0.0.1 f-secure.com
    127.0.0.1 www.f-secure.com
    127.0.0.1 kaspersky.com
    127.0.0.1 www.avp.com
    127.0.0.1 www.kaspersky.com
    127.0.0.1 avp.com
    127.0.0.1 www.networkassociates.com
    127.0.0.1 networkassociates.com
    127.0.0.1 www.ca.com
    127.0.0.1 ca.com
    127.0.0.1 mast.mcafee.com
    127.0.0.1 my-etrust.com
    127.0.0.1 www.my-etrust.com
    127.0.0.1 download.mcafee.com
    127.0.0.1 dispatch.mcafee.com
    127.0.0.1 secure.nai.com
    127.0.0.1 nai.com
    127.0.0.1 www.nai.com
    127.0.0.1 update.symantec.com
    127.0.0.1 updates.symantec.com
    127.0.0.1 us.mcafee.com
    127.0.0.1 liveupdate.symantec.com
    127.0.0.1 customer.symantec.com
    127.0.0.1 rads.mcafee.com
    127.0.0.1 trendmicro.com
    127.0.0.1 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


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.

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. Delete the entries that were added to the hosts file.
  3. Update the virus definitions.
  4. Restart the computer in Safe mode or VGA mode.
  5. Run a full system scan and delete all the files detected as W32.Gaobot.BAJ.
  6. Delete the value that was 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, 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. To delete the added lines from the Windows Hosts file


Note: The location of the Hosts file may vary and some computers may not have this file. For example, if the file exists in Windows 98, it will usually be in C:\Windows; and it is located in the C:\WINNT\system32\drivers\etc folder in Windows 2000. There may also be multiple copies of this file in different locations.

Follow the instructions for your operating system:
  • Windows 95/98/Me/NT/2000
    1. Click Start, point to Find or Search, and then click Files or Folders.
    2. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
    3. In the "Named" or "Search for..." box, type:

      hosts

    4. Click Find Now or Search Now.
    5. For each Hosts file that you find, right-click the file, and then click "Open With."
    6. Deselect the "Always use this program to open this program" check box.
    7. Scroll through the list of programs and double-click Notepad.
    8. When the file opens, delete the the following entries in the Hosts file:

      127.0.0.1 www.symantec.com
      127.0.0.1 securityresponse.symantec.com
      127.0.0.1 symantec.com
      127.0.0.1 www.sophos.com
      127.0.0.1 sophos.com
      127.0.0.1 www.mcafee.com
      127.0.0.1 mcafee.com
      127.0.0.1 liveupdate.symantecliveupdate.com
      127.0.0.1 www.viruslist.com
      127.0.0.1 viruslist.com
      127.0.0.1 viruslist.com
      127.0.0.1 f-secure.com
      127.0.0.1 www.f-secure.com
      127.0.0.1 kaspersky.com
      127.0.0.1 www.avp.com
      127.0.0.1 www.kaspersky.com
      127.0.0.1 avp.com
      127.0.0.1 www.networkassociates.com
      127.0.0.1 networkassociates.com
      127.0.0.1 www.ca.com
      127.0.0.1 ca.com
      127.0.0.1 mast.mcafee.com
      127.0.0.1 my-etrust.com
      127.0.0.1 www.my-etrust.com
      127.0.0.1 download.mcafee.com
      127.0.0.1 dispatch.mcafee.com
      127.0.0.1 secure.nai.com
      127.0.0.1 nai.com
      127.0.0.1 www.nai.com
      127.0.0.1 update.symantec.com
      127.0.0.1 updates.symantec.com
      127.0.0.1 us.mcafee.com
      127.0.0.1 liveupdate.symantec.com
      127.0.0.1 customer.symantec.com
      127.0.0.1 rads.mcafee.com
      127.0.0.1 trendmicro.com
      127.0.0.1 www.trendmicro.com


    9. Close Notepad and save your changes when prompted.

  • Windows XP
    1. Click Start, and then click Search.
    2. Click All files and folders.
    3. In the "All or part of the file name" box, type:

      hosts

    4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
    5. Click "More advanced options."
    6. Check "Search system folders."
    7. Check "Search subfolders."
    8. Click Search.
    9. Click Find Now or Search Now.
    10. For each Hosts file that you find, right-click the file, and then click "Open With."
    11. Deselect the "Always use this program to open this program" check box.
    12. Scroll through the list of programs and double-click Notepad.
    13. When the file opens, delete the the following entries in the Hosts file:

      127.0.0.1 www.symantec.com
      127.0.0.1 securityresponse.symantec.com
      127.0.0.1 symantec.com
      127.0.0.1 www.sophos.com
      127.0.0.1 sophos.com
      127.0.0.1 www.mcafee.com
      127.0.0.1 mcafee.com
      127.0.0.1 liveupdate.symantecliveupdate.com
      127.0.0.1 www.viruslist.com
      127.0.0.1 viruslist.com
      127.0.0.1 viruslist.com
      127.0.0.1 f-secure.com
      127.0.0.1 www.f-secure.com
      127.0.0.1 kaspersky.com
      127.0.0.1 www.avp.com
      127.0.0.1 www.kaspersky.com
      127.0.0.1 avp.com
      127.0.0.1 www.networkassociates.com
      127.0.0.1 networkassociates.com
      127.0.0.1 www.ca.com
      127.0.0.1 ca.com
      127.0.0.1 mast.mcafee.com
      127.0.0.1 my-etrust.com
      127.0.0.1 www.my-etrust.com
      127.0.0.1 download.mcafee.com
      127.0.0.1 dispatch.mcafee.com
      127.0.0.1 secure.nai.com
      127.0.0.1 nai.com
      127.0.0.1 www.nai.com
      127.0.0.1 update.symantec.com
      127.0.0.1 updates.symantec.com
      127.0.0.1 us.mcafee.com
      127.0.0.1 liveupdate.symantec.com
      127.0.0.1 customer.symantec.com
      127.0.0.1 rads.mcafee.com
      127.0.0.1 trendmicro.com
      127.0.0.1 www.trendmicro.com


    14. Close Notepad and save your changes when prompted.

3. 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 the Virus Definitions (LiveUpdate).

    Note: If this Trojan is running, you may not be able to run LiveUpdate. If you cannot, download the definitions using the Intelligent Updater (see the next bulleted item).

  • 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.

4. To restart the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.
  • For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
  • For Windows NT 4 users, restart the computer in VGA mode.

5. 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 as infected with W32.Gaobot.BAJ, write down the location and file name, and then click Delete.

6. 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 keys only. Read the document, "How to make a backup of the Windows registry," for instructions.
  1. Click Start > Run.
  2. Type regedit

    Then click OK.

  3. Navigate to the keys:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices

  4. In the right pane, delete the values, if present:

    "WSAConfiguration"="wmon32.exe"

  5. Exit the Registry Editor.

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