Threat Explorer

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Dixie@mm

Dixie@mm

Discovered:
13 March 2002
Updated:
13 February 2007

This worm is a DOS executable that spreads by using Microsoft Outlook (or Outlook Express) and mIRC, as well as infecting DOS executable files that it finds on your system. It arrives as an attachment with one of the following names: DIXIE.EXE, FLATLINE.EXE, or ROMCARD.EXE

Antivirus Protection Dates

  • Initial Rapid Release version 13 March 2002
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 13 March 2002
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date 13 March 2002
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

This worm usually arrives as an attachment to an email that contains one of the following two subjects:

FWD: Stuff
FWD: RE: Request

The message itself can vary slightly, but the following is a typical message:

Rulez :)

-----Original Message-----

> Hello!
> I've just finished this thing, give it a try!
> Please let me know if you like it.
> C ya

The first line can be replaced with the following line:

Cool! ;-)

and the other lines can be replaced by any of the following lines:

> Hi,
> Thanks for your attendance, here's it.
> I'd be happy if you could help me by sending any remarks.
> Bye now...


When it is activated, the worm searches for mIRC on the hard drive from which the worm was run. It also searches for an installation of Windows, which it assumes it has detected when it finds the file Win.com.

If the worm finds the \MIRC folder, it creates a malicious Script.ini file that sends a copy of the worm to any user who logs into the same IRC channel that you are using.

If the worm finds the \Windows folder, it creates a copy of itself there as well as creating a Winstart.bat file that will activate the worm every time that you start Windows.

The worm also inserts a Visual Basic Script on the system, and then executes it. This script emails the worm to the first 100 contacts in your address book.

This worm infects DOS executable files by prepending itself to an encrypted copy of the host file. If a copy of the worm which has not been prepended to a host is executed, it displays the following message:

Your program caused a divide overflow error.
If the problem persists, contact your program vendor.

The following strings can also be found with in the worms body:

Hey, bro! I'm the Dixie Flatline, best cowboy that ever punched deck.
dixie flatline - biocoded by worm

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.

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.
  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 Dixie@mm, click Repair.
  4. Files detected as Dixie@mm (dr) are actually copies of the worm (or files created by the worm). These files should be deleted.
  5. Using Windows Explorer, delete the Winstart.bat from the \Windows folder, and delete (or replace from a clean backup) the \Mirc\Script.ini file.


Writeup By: Atli Gudmundsson