Threat Explorer

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VBS.Lerki.A@m

VBS.Lerki.A@m

Discovered:
20 February 2004
Updated:
13 February 2007

VBS.Lerki.A@m is a virus that infects the files with .htt, .asp, .htm, .hta, .htx, and .html extensions and lowers the security settings in Microsoft Internet Explorer.

VBS.Lerki.A@m is written in Visual Basic Script.

Antivirus Protection Dates

  • Initial Rapid Release version 20 February 2004
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 20 February 2004
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date 23 February 2004
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When a file is infected with VBS.Lerki.A@m, the virus does the following:
  1. Modifies the value:

    "1201"="0"

    in the registry keys:
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0

      which lowers the security settings in Microsoft Internet Explorer.

  2. Overwrites any .htt, .asp, .htm, .hta, .htx, and .html files located in either the same folder as the virus or in the following locations:
    • C:\Windows\Web\Wallpaper
    • C:\Windows\Help
    • C:\Windows\Temp
    • C:\Program Files\Internet Explorer\Connection Wizard
    • C:\Program Files\Microsoft Office\Office\Headers
    • C:\Autoexec.bat
    • C:\Windows\Desktop
    • C:\Inetpub\wwwroot

  3. Attempts to email itself as an attachment to the first recipient in the Microsoft Outlook address book:

    The email has the following characteristics:

    Subject:
    RE: george bush pics

    Message:
    Take a look at these pics ...
    Regards,


Note: Due to bugs in the code, the virus does not always run.


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. Update the virus definitions.
  3. Run a full system scan and delete all the files detected as VBS.Lerki.A@m.
  4. Restore the security level of Microsoft Internet Explorer.

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

1. Disabling 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. 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 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).
  • 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.

3. Scanning for and deleting the infected files
  1. Start your Symantec antivirus software 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.Lerki.A@m, click Delete.
4. Restoring the security level of Microsoft Internet Explorer
To restore the security level, complete the following steps:
  1. Start Internet Explorer.
  2. Click Tools, and then click Internet Options.
  3. Select the Security tab.
  4. Change the security settings to the level you desire.


Writeup By: Keiichi Ito