W32.Taripox@mm

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Discovered: February 20, 2002
Updated: February 13, 2007 11:58:32 AM
Also Known As: I-Worm.Taripox.b, W32/Taripox.b, Carrytone
Type: Worm


W32.Taripox@mm is a UPX-packed mass-mailing worm that uses a new replication technique. Serving as a SMTP proxy on a local computer, it injects itself into the outgoing email messages.

Antivirus Protection Dates

  • Initial Rapid Release version February 20, 2002
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version February 20, 2002
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date February 20, 2002

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

Writeup By: Serghei Sevcenco

Discovered: February 20, 2002
Updated: February 13, 2007 11:58:32 AM
Also Known As: I-Worm.Taripox.b, W32/Taripox.b, Carrytone
Type: Worm


When it is executed, W32.Taripox@mm performs the following actions:

  1. It copies itself as \%Windows%\Mmoplib.exe.

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

    mmopl "\%Windows%\MMOPLIB.EXE"

    to the registry key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    to enable itself to run when Windows starts.
  3. The worm remaps the SMTP server of the Default Mail Account to the local host IP address (127.0.0.1). To do this, the worm modifies the following file:

    \%Windows%\system32\drivers\etc\HOSTS

    NOTE: Because a different HOSTS file is used by Windows 95/98/Me for the locally predefined host name resolutions, the worm may not replicate under these operating systems.
  4. Running as an SMTP proxy, W32.Taripox@mm listens on port 25 (SMTP port). Whenever an email client attempts to establish a connection with the SMTP server, it creates a stream socket for the internetwork TCP/IP connection and establishes a connection to that socket using port 25 and the IP address of the SMTP server. This IP address will not be resolved for the host since it is already remapped by the worm. This results in establishing a connection with the worm, as shown in the following scheme:



    The email client starts to communicate with W32.Taripox@mm as it would with the real SMTP server. The worm examines and passes the communication streams to and from the SMTP server. When the email program transmits the "DATA" command to initiate the email transmission, W32.Taripox@mm intercepts the DATA stream and sends different data: the original message with the injected viral attachment. The worm preserves the sender, the recipient, and the message body of the original email message. However, if the original attachment is smaller than 6 KB, the worm adds its own viral body. The file name of the viral MIME-encoded attachment is the recipient's name with the ".doc.pif" string appended. The worm places "taricone" as the viral attachment name so that some email clients will display this name instead. The viral "taricone" file is also attached to an email if the original message contains no attachments.

    For example: "Recipient.doc.pif" (file size: 21,504 bytes), "Original.dat" (original attachment with the file size < 6 KB).

    If the original attachment is larger than 6 KB, the worm substitutes it with the MIME-encoded viral body, retaining the original file name as a name of the viral attachment. If the original attachment has an extension other than .exe, the file name of the viral attachment is the original attachment file name with the ".exe" extension appended to it.

    For example: "Original.dat.exe" (file size: 21,504 bytes) or "Original.exe" (file size: 21,504 bytes) if the original attachment was "Original.exe".
  5. To hide its activity as much as possible, the worm keeps a five-member queue (FIFO) in the value

    MRU

    of the registry key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Media Optimization Library

    Primarily, the value contains the following string:

    "NULL,NULL,NULL,NULL,NULL,"

    Before the DATA stream interception, the worm checks whether the recipient name is among the members of this queue.
    • If it is not, the virus sends itself to that recipient and add the recipient's name to the queue, pushing out the last member from the queue.
    • If the recipient is found in the queue, the virus will not submit itself to that person again.


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: Serghei Sevcenco

Discovered: February 20, 2002
Updated: February 13, 2007 11:58:32 AM
Also Known As: I-Worm.Taripox.b, W32/Taripox.b, Carrytone
Type: Worm


Remove the registry key and the values added by the W32.Taripox@mm to registry, remove the SMTP server host resolution from the HOSTS file, restart the computer, and remove any files that are detected as W32.Taripox@mm.

To edit the registry:

CAUTION : We strongly recommend 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 back up 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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, delete the following value:

    mmopl       \%Windows%\MMOPLIB.EXE

    where %Windows% is the Windows folder.
  5. Navigate to and delete the key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Media Optimization Library
  6. Click Registry, and click Exit.

To edit the HOSTS file:
  1. Start Notepad or another text editor.
  2. Click File, and click Open.
  3. In the "Files of type:" box, choose "All files."
  4. Browse to the folder \%Windows%\system32\drivers\etc\.

    NOTE: %Windows% is the folder in which you installed Windows.
  5. Double-click the HOSTS file to open it.
  6. Remove any strings that point any mail server to the local host 127.0.0.1. Do not remove the line that contains the "localhost" mapping to the IP address 127.0.0.1.
  7. Close Notepad, and save the changes when prompted.

To remove the worm:
  1. Restart the computer to make sure that the worm is not loaded. (Do not skip this step).
  2. 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 if 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 if 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.
  3. 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.
  4. Run a full system scan.
  5. Delete all files that are detected as W32.Taripox@mm.


Writeup By: Serghei Sevcenco