Threat Explorer

The Threat Explorer is a comprehensive resource consumers can turn to for daily, accurate, up-to-date information on the latest threats, risks and vulnerabilities.

VBS.Liong@mm

VBS.Liong@mm

Discovered:
25 June 2001
Updated:
13 February 2007
Also Known As:
VBS.LoveLetter.CQ

VBS.Liong@mm is a minor variant of the LoveLetter virus family. This variant does not contain the viral overwriting function found in many of the variants, but it does contain mass-mailing and network-awareness functions.

The email arrives in the following format:

Subject:  One of this mail
Body:  True Story....
Attachment: mylinong.exe

Norton AntiVirus detects the attachment as W32.Liong.

This worm modifies the registry so that the worm is run when Windows starts. The worm creates the file Mylinong.hta and displays it the first time that the worm is executed. This HTML page contains a note from the author of the script to his love.

NOTE: Virus definitions dated prior to July 3, 2001, detect this script as VBS.LoveLetter.CQ.



After the worm has resided on an infected system for more than 14 days, the next that time it executes it will delete all of the files and folders that it created.

NOTES:
  • If you are using Norton AntiVirus 2001, a free program update that includes Script Blocking is available. Please run LiveUpdate to obtain this.
  • For other versions of Norton AntiVirus, SARC offers a tool to disable the Windows Scripting Host.


Antivirus Protection Dates

  • Initial Rapid Release version 25 June 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 25 June 2001
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When executed, the worm performs the following actions:
  1. It obtains the IP address of your computer by using the command ipconfig /Batch, which outputs the results to a temporary file. This command does not execute properly on computers running Windows NT/2000.
  2. Using the IP address that it obtained, the worm selects a random IP address on the same subnet and attempts to map that system as drive J. For example, based on the IP address 24.111.2.140, the worm might choose the IP address 24.111.2.80 and attempt to share that system.
  3. If the drive is mapped successfully, the worm copies the file C:\Windows\Linong.vbs to the following locations on that system:

    j:\
    j:\windows\startm~1\programs\startup\
    j:\windows\
    j:\windows\start menu\programs\startup\
  4. It then modifies a "Timeout" key in the Windows registry so that no message is displayed when the script takes a long time to run, as it typically does.
  5. It creates the values

    bkali
    bdate

    in the registry key

    HKEY_CURRENT_USER\Software\Microsoft\
    Windows Scripting Host\Settings

    These values keep track of various counters that are used by the worm.
  6. It sets the default home page for Internet Explorer to the address http:/ /www.thewebpost.com/lovepoems/1198/dpt112098ily.shtml.
  7. The worm adds the value

    Kern32lLin  \<Windows System folder>\Kern32Lin.vbs

    to the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    so that the worm runs when Windows starts.
  8. The worm adds the value

    Vbrun32DLL  \<Windows folder>\vbrun32DLL.vbs

    to the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices

    so that the worm runs when Windows starts.
  9. It creates 600 folders in the root directory of drive C. Each folder is named LINONG I LOVE YOU MY FOLDER??? where ??? are the numbers 1-600.
  10. It attempts to email all addresses in the Microsoft Outlook Address Book. It attaches the file Mylinong.exe to the outgoing emails. This file is detected as W32.Liong.
  11. Finally, the file Mylinong.hta is created in the Windows temporary folder. This file is displayed whenever the worm is executed. The file contains a brief note from the script's author to his love.


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.

To remove this worm, delete files detected as VBS.Liong@mm, remove the changes it made to the registry, and then reset your Internet Explorer home page.

To remove the worm:
  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  3. Delete any files detected as VBS.Liong@mm.

To edit the registry:
    CAUTION: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.
  1. Click Start, and 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

    Kern32lLin
  5. Navigate to the key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices
  6. In the right pane, delete the value

    Vbrun32DLL
  7. Navigate to the key

    HKEY_CURRENT_USER\Software\Microsoft\Windows Scripting Host\Settings
  8. In the right pane, delete the values

    bkali
    bdate
  9. Exit the Registry Editor.

To reset the Internet Explorer home page:
  1. Start Microsoft Internet Explorer.
  2. Connect to the Internet and go to the page that you want to set as your home page.
  3. Click Tools, and click Internet Options.
  4. On the General tab, under Home page, click Use Current and then click OK.


Writeup By: Brian Ewell