W32.Masy.Worm

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Discovered: May 06, 2002
Updated: February 13, 2007 11:55:09 AM
Also Known As: WORM_MASANA.A, I-Worm.Masana
Type: Worm
Systems Affected: Windows


W32.Masy.Worm is a mass-mailing worm that sends itself to addresses that it finds in files that have an extension that contains the letters htm. It also makes use of the Deploit Exploit to execute with administrator rights. It will also attempt to add a user, masyanechkaa, with administrative rights.

It arrives in an email with the following characteristics:
Subject: Masyanya!
Attachment: Masyanya.exe

NOTE: The mass-mailing routine could not be reproduced in a controlled laboratory environment.

Antivirus Protection Dates

  • Initial Rapid Release version May 07, 2002
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version May 07, 2002
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date May 08, 2002

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

Writeup By: Douglas Knowles

Discovered: May 06, 2002
Updated: February 13, 2007 11:55:09 AM
Also Known As: WORM_MASANA.A, I-Worm.Masana
Type: Worm
Systems Affected: Windows


When W32.Masy.Worm is executed, it copies itself to the %System% directory as Msys32.exe.

NOTE: %System% is a variable. The worm locates the \Windows\System folder (by default this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.

It copies itself to Eexplorer.exe in the current directory and drops the files ERunAsX.dll and ERunAsX.exe. Both of these files make use of the Deploit Exploit.

The Deploit Exploit is an exploit that functions on Windows NT 4.0 and Windows 2000. It obtains a handle to an existing process and then creates a debug thread within that process. This debug thread then allows code to be executed with administrative rights.

W32.Masy.Worm then obtains the email addresses from all files that include the letters htm in the extension (for example, star.htm, star.html) on the infected computer and then attempts to send the following email message:

Subject: Masyanya!
Body:
Hi, here is a new film about Masyanya and V.V.Putin!!!
Homepage: http: //mult.ru

Attachment: Masyanya.exe

Depending upon the infected computer's default language, the above email message may be translated to Russian text. The worm also sends the following email message to masyana@nm.ru:

Subject : Masyanya!
Body: gygygy!

NOTE: None of the above symptoms could be reproduced in the lab environment.

The worm also attempts to add the user masyanechkaa, with password and superpassword, to the Administrators group. However, this part of the worm infection process has a bug that blocks this action from being performed.

On Windows 95/98/Me computers, the worm also changes the shell line in the [boot] section of the System.ini from

shell = Explorer.exe

to

shell = Explorer.exe msys32.exe -dontrunold

It also adds the value

    "Warn on Mapi Send" = 0

    to the registry key

    HKEY_CURRENT_USER\Identities\(Unique User String)\SoftWare\Microsoft\Outlook Express\5.0\Mail

    The worm also executes the following command, which allows the dropped file Eexplorer.exe to run with administrative rights:

    cmd.exe /c eRUNASX.exe eexplorer.exe

    If the day of the week is Monday, then W32.Masy.Worm activates a payload; this payload performs an ICMP Denial of Service attack on kavkaz.org.

    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: Douglas Knowles

    Discovered: May 06, 2002
    Updated: February 13, 2007 11:55:09 AM
    Also Known As: WORM_MASANA.A, I-Worm.Masana
    Type: Worm
    Systems Affected: Windows


    To remove W32.Masy.Worm, scan with NAV and delete files that are detected as W32.Masy.Worm, delete ERunAsX.dll and ERunAsX.exe, and remove the value that the worm added to the registry. If you are running Windows 95/98/Me, then remove the entry that the worm left in System.ini.

    Detailed instructions follow.

    To delete files that are detected as W32.Masy.Worm:

    1. Obtain the most recent virus definitions. There are two ways to do this:
      • Run LiveUpdate. LiveUpdate is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
      • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

        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.
    2. 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.
    3. Run a full system scan.
    4. Delete all files that are detected as W32.Masy.Worm.

    To delete ERunAsX.dll and ERunAsX.exe:
    Follow the instructions for your version of Windows.

    Windows 95/98/Me/NT/2000
    1. Click Start, point to Find or Search, and then click Files or Folders.
    2. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
    3. In the "Named" or "Search for..." box, type--or copy and paste--the following file names:

      ERunAsX.dll ERunAsX
    4. Click Find Now or Search Now.
    5. Delete the files that result from the search.

    Windows XP
    1. Click Start, and then click Search.
    2. Click All files and folders.
    3. In the "All or part of the file name" box, type--or copy and paste--the following file names:

      ERunAsX.dll ERunAsX
    4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
    5. Click "More advanced options."
    6. Check "Search system folders."
    7. Check "Search subfolders."
    8. Click Search.
    9. Delete the files that result from the search.

    To edit System.ini:

    NOTES:
    • Follow the steps in this section only if you are running Windows 95/98/Me.
    • (For Windows Me users only) Due to the file-protection process in Windows Me, a backup copy of the file that you are about to edit exists in the C:\Windows\Recent folder. Symantec recommends that you delete this file before you continue with the steps in this section. To do this using Windows Explorer, go to C:\Windows\Recent, and in the right pane select the Win.ini file and delete it. It will be regenerated as a copy of the file that you are about to edit when you save your changes to that file.
    1. Click Start, and click Run.
    2. Type the following, and then click OK.

      edit c:\windows\system.ini

      The MS-DOS Editor opens.

      NOTE: If Windows is installed in a different location, make the appropriate path substitution.
    3. In the [boot] section of the file, look for a line similar to the following:

      shell = explorer.exe msys32.exe -dontrunold
    4. If it exists, select msys32.exe -dontrunold and then press Delete. When you have finished, only shell = explorer.exe should remain.
    5. Click File, and click Save.
    6. Click File, and click Exit.

    To edit 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 only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
    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:

      HKEY_CURRENT_USER\Identities\(Unique User String)\SoftWare\Microsoft\Outlook Express\5.0\Mai
    4. In the right pane, delete the following value:

      Warn on Mapi Send 0
    5. Exit the Registry Editor.


    Writeup By: Douglas Knowles