Threat Explorer

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VBS.Moon.B

VBS.Moon.B

Discovered:
14 January 2003
Updated:
13 February 2007
Systems Affected:
Windows

VBS.Moon.B is a VBScript threat that is similar to VBS.Moon@mm . VBS.Moon.B uses the Windows file Wscript.exe to run its instructions and copies itself to the \Windows folder. VBS.Moon.B also reduces the security level of Internet Explorer, sets the speaker mode of the modem, and changes the Internet Explorer home page.

Antivirus Protection Dates

  • Initial Rapid Release version 15 January 2003
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 15 January 2003
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date 15 January 2003
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When VBS.Moon.B is executed, it does the following:
    1. Copies itself as \Windows\Fotompg.vbs.
    2. Adds the value:

      explorer     "wscript.exe fotompg.vbs %"

      to the registry key:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

      so that the Trojan runs when you start Windows.
    3. Changes the home page of Internet Explorer by adding the value:

      Start Page http:/ /www.kogalu.com/sou/internz/enter3.htm

      to the registry key:

      HKEY_CURRENT_USER\SOFTWARE\Microsoft\Internet Explorer\Main

      so that this particular Web page opens when you start Internet Explorer.
    4. Decreases the Internet Explorer security level by adding the value:

      1004 00

      to the registry key:

      HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    5. Sets the speaker mode of the modem by adding the value:

      SpeakerMode_Dial  "M0"
      SpeakerMode_Off     "M1"

      to the registry key:

      HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Modem\0000\Settings

      and:

      DialUI  00000007

      to the registry key:

      HKEY_LOCAL_MACHINE\RemoteAccess
    6. Checks whether the file "XXX_Adult.exe" exists in the \Windows folder. If the file is found, the threat adds the value:

      explorervs  00

      to the registry key:

      HKEY_CURRENT_USER\software\moon

      And, the threat changes the Internet Explorer home page by adding the value:

      Start Page http:/ /www.viplegal.com/cgi-bin/top/in.cgi?id=omanko

      to the registry key:

      HKEY_CURRENT_USER\SOFTWARE\Microsoft\Internet Explorer\Main
    7. Checks that the date is 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, or 30.
      • If the date is one of the aforementioned dates, the threat checks whether the file "XXX_Adult.exe" exists in the \Windows folder.
        • If the file is found, the threat sets the speaker mode of the modem, as described in step 5, and also runs the XXX_Adult.exe file.
        • If the file is not found, the threat follows step 3, 4, and 5 again, and then it changes the Internet Explorer home page to:
          http:/ /www.viplegal.com/cgi-bin/top/in.cgi?id=omanko.
      • If the date is not one of the aforementioned dates, the threat checks whether the file "XXX_Adult.exe" exists in the \Windows folder. If the file is there, the threat randomly chooses to repeat step 5 and run the XXX_Adult.exe file, or to repeat step 3.

    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.

    These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
    1. Update the virus definitions.
    2. Run a full system scan, delete all the files detected as VBS.Moon.B.
    3. Delete the value:

      explorer     "wscript.exe fotompg.vbs %"

      from the registry key:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

      and delete the registry key:

      HKEY_CURRENT_USER\software\moon
    4. Reset the Internet Explore home page and security level.

    For specific details on each of these procedures, read the following instructions.


    1. 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 the 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), in the "Protection" section, at the top of this writeup.
    • 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), in the "Protection" section, at the top of this writeup.

      The Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

    2. 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 VBS.Moon.B, click Delete.

    3. Deleting the value and key from the registry

    CAUTION : Symantec strongly recommends that you back up the registry before you make 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, and 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:

      explorer "wscript.exe fotompg.vbs %"
    5. Navigate to and delete the key:

      HKEY_CURRENT_USER\software\moon
    6. Click Registry, and then click Exit.

    4. Resetting the Internet Explorer
    1. Start Microsoft Internet Explorer.
    2. Connect to the Internet and go to the page you want to set as your home page.
    3. Click the Tools menu, and then click Internet Options.
    4. In the Home page section of the General tab, click Use Current, and then click OK.
    5. Click the Security tab and select the Internet icon.
    6. Click Custom level.
    7. In the list box, choose Medium.
    8. Click Reset.
    9. Click OK, and then click OK again to exit.


    Writeup By: Jason Pan