X97M.Laroux.KU

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Discovered: October 02, 1999
Updated: February 13, 2007 12:40:40 PM
Also Known As: X97M/Majo.gen, XM/Majoduck.A
Type: Virus, Macro


X97M.Laroux.KU is a virus that infects Microsoft Excel worksheets. It contains a short comment in the virus source code:

Macro Majoduck_SK_1 ,Made in Slovakia

This virus may execute damaging payloads, depending on the selection of a random number by the virus.



This definition was modified on October 29, 2001, to better handle detection of this virus or variants of the code.

Antivirus Protection Dates

  • Initial Rapid Release version October 08, 1999
  • Latest Rapid Release version October 08, 1999
  • Initial Daily Certified version October 08, 1999
  • Latest Daily Certified version October 08, 1999

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Patrick Nolan

Discovered: October 02, 1999
Updated: February 13, 2007 12:40:40 PM
Also Known As: X97M/Majo.gen, XM/Majoduck.A
Type: Virus, Macro


When it is run, X97M.Laroux.KU creates an infected worksheet in the \Xlstart folder named Office_.xls. This worksheet loads when Excel is started.

This virus exists in a single macro module named Majoduck_SK_1. It hooks the Excel event handler of opening infected worksheets in order to run its code. In some cases the virus may delete files or the contents of the worksheet.

The virus runs instructions that pick a random number between 1 and 301. If the number chosen is:

  • Either 7 or 11, then all chart objects in the current worksheet may be deleted
  • Greater than 297, the virus deletes files in the current folder (the same folder as the virus) that have the .hlp file extension
  • Equal to 77, the virus deletes files in the current folder that have the .b* file extension
  • Either 1 or 3, the virus delete files in the current folder that have the .c* file extension
  • Less than or equal to 6, the virus delete files in the current folder that have the .dll file extension


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.

Writeup By: Patrick Nolan

Discovered: October 02, 1999
Updated: February 13, 2007 12:40:40 PM
Also Known As: X97M/Majo.gen, XM/Majoduck.A
Type: Virus, Macro


Run LiveUpdate to make sure that you have the most recent virus definitions.

  1. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
  2. Run a full system scan.
  3. If any files are detected as infected by X97M.Laroux.KU, click Repair.


Writeup By: Patrick Nolan