Threat Explorer

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VBS.Loveletter.CN@mm

VBS.Loveletter.CN@mm

Discovered:
31 May 2001
Updated:
13 February 2007
Also Known As:
VBS.Loveletter.CM@mm (AVX), VBS.Lopez.A@mm, JENNIFERLOPEZ_NAKED.JPG.vbs
Download Removal Tool

This is a minor variant of the LoveLetter virus family. This virus may arrive in the following format by email:

Subject:  Where are you?
Body:  This is my pic in the beach!
Attachment:  JENNIFERLOPEZ_NAKED.JPG.vbs

This virus also drops the file Cih_14.exe, which is a dropper for the CIH virus, and attempts to run it.

Click here to view the entire list of known VBS.LoveLetter variants.




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 01 June 2001
  • Latest Rapid Release version 08 August 2016 revision 023
  • Initial Daily Certified version 01 June 2001
  • Latest Daily Certified version 09 August 2016 revision 001
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When executed, this virus does the following:
  1. First, it 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. This virus then indexes all available drives, and searches for files with specific extensions:
    • Files with .vbe, .jpg, and .jpeg extensions are replaced with a copies of the script virus.
    • Files with .js, .jse, .css, .wsh, .sct, and .hta extensions are replaced with copies of the script virus, and duplicate files are created with the .vbs extension appended to them. For example, Filename.wsh becomes Filename.wsh.vbs.
    • Files with .mp2 and .mp3 extensions are duplicated with a .vbs extension appended to them. The original files are then marked as hidden.
  2. The virus creates the registry key

    HKEY_CURRENT_USER\Software\
    JENNIFFERLOPEZ_NAKED\Worm made in algeria
  3. The virus adds the value

    WORM  wscript.exe  \<Windows folder>\JENNIFERLOPEZ_NAKED.JPG.vbs %

    to the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\
    Windows\CurrentVersion\Run

    so that the worm runs when Windows starts.
  4. This virus checks the registry key

    HKEY_CURRENT_USER\Software\JENNIFFERLOPEZ_NAKED

    to see if it is set to the value

    mailed = 1

    If it is not, it begins the email routine. After the email routine, the value is set to 1.
  5. Finally, the virus writes a line-by-line hexadecimal file and saves it as \Windows\Cih_14.exe. This file contains a dropper for the CIH virus. The dropped file is then executed. If it is executed, it becomes memory resident in Windows 98/Me and infects Portable Executable (PE) files.


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.

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


Writeup By: Patrick Nolan