Threat Explorer

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VBS.Lisa.A@mm

VBS.Lisa.A@mm

Discovered:
25 February 2003
Updated:
13 February 2007
Systems Affected:
Windows

VBS.Lisa.A@mm is a mass-mailing worm that is written in the Visual Basic Scripting (VBS) language. This worm attempts to spread through Microsoft Outlook, mIRC, and KaZaA. The email arrives with a subject of "Click YES and vote against war!". There is no mail attachment as the worm is distributed as script in the body of the email.

VBS.Lisa.A@mm may create up to 5,000 folders on the C drive and may delete critical system files. On Windows 95/98/Me computers, the worm may format the C drive.

NOTE: Virus definitions dated prior to February 26, 2003 may detect this as Bloodhound.VBS.Worm.

Antivirus Protection Dates

  • Initial Rapid Release version 26 February 2003
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 26 February 2003
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date 26 February 2003
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When VBS.Lisa.A@mm is executed, it does the following:
  1. Creates an empty Visual Basic Script (VBS) file as \Windows\<file name>.vbs.

    NOTE: The worm randomly selects the <file name>, which is seven characters in length.
  2. Adds the value:

    <file name>   "wscript.exe \Windows\<file name>.vbs %"

    to the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    so that the worm runs when you start Windows.
  3. Creates an HTML file that has embedded VBS code. The embedded VBS code runs and attempts to copy the worm's code into the \Windows\<file name>.vbs file, and then execute that particular file.
  4. Copies itself to the KaZaA share folder as the following files:
    • Silvia Saint Gangbang.avi.vbs
    • Britney Spears nude.jpg.vbs
    • Christina Aguilera Nipple.jpg.vbs
    • Lolita.jpg.vbs
    • Madonna - Song.mp3.vbs
    • Jennifer Lopez.mp3.vbs

  5. Purges all the messages in the Microsoft Outlook Inbox that have the subject "Click YES and vote against war!"
  6. Sends the following message to all the contacts in the Microsoft Outlook Address Book:

    Subject: "Click YES and vote against war!"
    Message: The message consists of the body of the HTML file that was created in step 3.
  7. Adds the registry key:

    HKEY_CURRENT_USER\Lisa\Mail

    and sets the send value to 1 so that the email routine is performed only once.
  8. Creates up to 5,000 randomly named folders under the root of drive C.
  9. Creates one text file in each of the folders that it created. The text file contains the text:

    I will never stop loving you.
  10. Searches all the subfolders in all the drives. If the worm finds:
    • An Mirc.ini file, the worm attempts to spread itself using mIRC.
    • A .vbs or .vbe file, the worm will infect the file by replacing the content of the file with its own VBS code.
  11. Attempts to delete all the .doc files.
  12. Deletes the file, \Windows\Regedit.exe.
  13. Deletes the following files from the \Windows folder if the computer has been infected by the worm for more than three days:
    • User.dat
    • User.bak
    • System.dat
    • System.bak
    • Win.ini

  14. Sets the value:

    NoDesktop = 00000001

    in the registry key:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Policies\Explorer
  15. Adds the line:

    format c: /q /autotest

    to the Autoexec.bat file so that drive C is formatted the next time you start your Windows 95/98/Me computer.


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. Delete the line that the worm added to the Autoexec.bat file (Windows 95/98/Me).
  2. Update the virus definitions.
  3. Run a full system scan and delete all the files detected as VBS.Lisa.A@mm.
  4. Reverse the changes that the worm made to the registry.
  5. Delete the folders that the worm created.

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

1. Deleting the line added to the Autoexec.bat file
If you are running Windows 95/98/Me, follow these steps:
  1. The function you perform depends on your operating system:
    • Windows 95/98: Go to step b.
    • Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made a backup copy of the Autoexec.bat file that you are to edit. If this backup copy exists, it will be in the C:\Windows\Recent folder. Symantec recommends that you delete this file before continuing with the steps in this section. To do this:
      • Start Windows Explorer.
      • Browse to and select the C:\Windows\Recent folder.
      • In the right pane, select the Autoexec.bat file and delete it. The Autoexec.bat file will be regenerated when you save your changes to it in step f.
  2. Click Start, and then click Run.
  3. Type the following:

    edit c:\autoexec.bat

    And then click OK. (The MS-DOS Editor opens.)

    NOTE: If Windows is installed in a different location, make the appropriate path substitution.
  4. Look for a line similar to:

    format c: /q /autotest

    If it exists, delete it.
  5. Click File, and then click Save.
  6. Click File, and then click Exit.

2. 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.

3. 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.Lisa.A@mm, click Delete.
4. Reversing the changes made to 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:

    %randfile%    "wscript.exe \Windows\%randfile%.vbs %"
  5. Navigate to the key:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Policies\Explorer
  6. In the right pane, delete the value:

    NoDesktop = 00000001
  7. Exit the Registry Editor.
5. Deleting the folders
  1. Start Windows Explorer.
  2. Navigate to the root of the C drive.
  3. Delete all the folders that contain only one .txt file whose text consists of "I will never stop loving you."
  4. Exit Windows Explorer.


Writeup By: Jason Pan