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07 September 2001
13 February 2007

VBS.Trappy@mm is a Visual Basic Script (VBS) worm. It infects .htm, .plg, .asp, and .vbs files. It replicates using MAPI objects to spread itself as an attachment.

The worm exploits a known Microsoft Outlook Express security hole so that the worm is executed without having to run any attachment. Microsoft has patched this security hole to eliminate security vulnerabilities in "Scriptlet.TypLib" ActiveX controls. The patch is available at:

Antivirus Protection Dates

  • Initial Rapid Release version 07 September 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 07 September 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.

VBS.Trappy@mm is a viral Visual Basic Script that is contained in an .htm, .plg, .asp, or .vbs file. This worm can infect your computer if it is displayed in the preview pane of Outlook Express or if the viral page is opened in Internet Explorer. This can be prevented by applying the Microsoft security update patch, which is available at the following Microsoft Web site:

When the script is executed, it performs the following actions:
  1. It drops itself as Mdm.vbs, User.dll, Readme.html, and System.dll file into the %System% folder, and as Profile.vbs into the %Windows% folder.
  2. It adds the following value

    Mdm %SYSTEM%\Mdm.vbs

    to the registry key


    and the value

    Profile %WINDOWS%\Profile.vbs

    to the registry key

  3. The script then replicates using MAPI objects sending an email message to all contacts in the address book. The message has the following format:

    Subject and Message Body are the same; it is one from the following list:
    Thanks for helping me!
    The police are investigating the robbery
    An application for a job
    The aspects of an application process pertinent to OSI
    What a pleasant weather. Why not go out for a walk?
    These countries have gone / been through too many wars
    We've fixed on the 17th of April for the wedding
    The wind failed and the sea returned to calmness.
    The sitting is open!

  4. Then, intending to perform a denial-of-service (DoS) attack, the script sends an email message to the following email addresses:
  5. The script then looks for .htm, .vbs, .asp, and .plg files in all folders (except the %Temp% folder) on both local and mapped drives. The script infects these files, prepending the viral code to the original contents of the files.
  6. If the current date is July 5, the script drops the %System%\75.htm file. When this file is opened, it redirects the browser to the location "c:/con/con." If the operating system is Windows 9x, an attempt to open the mentioned address might lead to the "blue screen" and the computer may stop responding completely. To open this page every time that the computer starts up, the script adds the value

    75 %System%\75.htm

    to the registry key

  7. If the domain name, computer name, or user name for the current computer contains one of the following strings:
    white home
    central intelligence agency
    american stock exchang
    chief executive

    the script appends"DELTREE c:\" line to C:Autoexec.bat to delete the contents of drive C.
  8. It then attempts to delete all files and folders in the root of all local drives. The script displays the name of every folder that it deletes, as follows:

  9. VBS.Trappy@mm tries to infect the home page hosted on the current computer, but because of the bug, it fails.


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 any files detected as VBS.Trappy@mm and delete the registry key values that the worm added. Then delete the entry that the worm added to the Autoexec.bat.

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. Be sure that NAV is configured to scan all files.
  3. Delete all files that are detected as VBS.Trappy@mm.

To edit the registry:
CAUTION : We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys that are specified. Please see the document How to back up the Windows registry before you proceed.
  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 following key:

  4. In the right pane, click on the following values and press Delete:

  5. Click Yes at the next prompt.
  6. Navigate to the following key:

  7. In the right pane, click the following value and press Delete:

  8. Click Yes at the next prompt.
  9. Click Registry, and then click Exit to save the changes.
To remove the worm entry from the Autoexec.bat file:
  1. Click Start, and click Run.
  2. Type the following, and then click OK.

    edit c:\autoexec.bat
  3. When the MS-DOS Editor opens, locate and delete the following entry:

    DELTREE c:\
  4. Click File, and click Save.
  5. Click File, and click Exit.

Writeup By: Serghei Sevcenco