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Discovered: August 22, 2005
Updated: February 13, 2007 12:43:38 PM
Type: Trojan Horse
Systems Affected: Windows

Backdoor.Tixanbot is a Trojan horse that gives a remote attacker control over the compromised computer. It also ends security-related processes, stops services, and sends links to other users using MSN Messenger.

Antivirus Protection Dates

  • Initial Rapid Release version August 23, 2005
  • Latest Rapid Release version May 07, 2019 revision 006
  • Initial Daily Certified version August 23, 2005 revision 002
  • Latest Daily Certified version May 07, 2019 revision 008
  • Initial Weekly Certified release date August 23, 2005

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

Writeup By: Rodney Andres

Discovered: August 22, 2005
Updated: February 13, 2007 12:43:38 PM
Type: Trojan Horse
Systems Affected: Windows

When Backdoor.Tixanbot is executed, it performs the following actions:

  1. Displays a fake error message with the following properties:

    Title: Error Patching File
    Message: Messenger not found!

  2. Copies itself as %System%\[RANDOM NAME]\svshost.exe.

    Note: %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  3. May create the following files that are shortcuts to the file %System%\[RANDOM NAME]\svshost.exe, so that it runs at startup:

    • %User Profile%\Start Menu\Programs\Startup\svshost.lnk
    • %User Profile%\Start Menu\Programme\Autostart\svshost.lnk

      Note: %UserProfile% is a variable that refers to the current user's profile folder. By default, this is C:\Documents and Settings\[CURRENT USER] (Windows NT/2000/XP).

  4. Adds the value:

    "svshost" = "%System%\[RANDOM NAME]\svshost.exe"

    to the registry subkeys:


    so that it runs every time Windows starts.

  5. Adds the value:

    "Start" = "4"

    to the registry subkeys:


    so that it disables Windows security features.

  6. Ends the following processes, some of which are security-related:

    • kavsvc.exe
    • msconfig.exe
    • kav.exe
    • mcvsshld.exe
    • mcagent.exe
    • mcvsrte.exe
    • mcshield.exe
    • mcvsftsn.exe
    • mcdash.exe
    • mcvsescn.exe
    • mcinfo.exe
    • mpfagent.exe
    • mpftray.exe
    • mpfservice.exe
    • mskagent.exe
    • mcmnhdlr.exe
    • sndsrvc.exe
    • vsmon.exe
    • usrprmpt.exe
    • ccapp.exe
    • ccevtmgr.exe
    • spbbcsvc.exe
    • ccsetmgr.exe
    • symlcsvc.exe
    • npfmntor.exe
    • navapsvc.exe
    • issvc.exe
    • ccproxy.exe
    • navapw32.exe
    • navw32.exe
    • smc.exe
    • outpost.exe
    • zlclient.exe
    • pandaavengine.exe
    • msblast.exe
    • penis32.exe
    • teekids.exe
    • bbeagle.exe
    • d3dupdate.exe
    • sysmonxp.exe
    • i11r54n4.exe
    • irun4.exe
    • mscvb32.exe
    • sysinfo.exe
    • mwincfg32.exe
    • wincfg32.exe
    • winsys.exe
    • zapro.exe
    • winupd.exe
    • enterprise.exe
    • regedit.exe
    • hijackthis.exe
    • gcasdtserv.exe
    • gcasserv.exe
    • pcctlcom.exe
    • tmntsrv.exe
    • tmproxy.exe
    • pccguide.exe
    • tmpfw.exe
    • pcclient.exe
    • taskmgr.exe
    • ethereal.exe

  7. Closes Windows with the following title:

    • microsoft antispyware*
    • hijackthis*

  8. Ends the following security-related services, and sets their start type to disabled:

    • wscsvc
    • SharedAccess
    • srservice
    • kavsvc
    • mcupdmgr.exe
    • McShield
    • MCVSRte
    • MpfService
    • GuardDogEXE
    • ISSVC
    • navapsvc
    • Symantec Core LC
    • ccEvtMgr
    • SNDSrvc
    • ccProxy
    • ccPwdSvc
    • ccSetMgr
    • SPBBCSvc
    • SAVScan
    • SBService
    • SmcService
    • OutpostFirewall
    • vsmon
    • CAISafe
    • PcCtlCom
    • tmproxy
    • Tmntsrv

  9. Deletes the following security-related values:

    "VirusScan Online"
    "Symantec NetDriver Monitor"
    "Outpost Firewall"
    "Zone Labs Client"

    from the registry subkey:


  10. Adds the following text to the hosts file to block access to some security-related websites:

  11. Opens a back door by connecting to an IRC server on through TCP port 37737. This back door allows the attacker to perform the following actions on the compromised computer:

    • Download files
    • Download updates to the Trojan
    • Perform a denial of service attack
    • Obtain system information - computer name, OS
    • Run shell commands
    • Change the start page in Internet Explorer.
    • Open a URL in a browser
    • Send a message to other users via MSN messenger.

  12. Sends one of the following messages to other MSN messenger users followed by a link which when clicked, downloads a copy of the Trojan:

    LMAO, this is freaking me out!!
    looooooool....check this out !!!
    Automessage : download the new MSN update here!
    rofl, this ownz!!
    Hej, you already updated your MSN?
    Get the new MSN Messenger here :
    Click here if you want more MSN emotions:
    w0000t, you have to check this out!
    lmao, this roxXxX!!
    wow wow have to check this out!!!


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: Rodney Andres

Discovered: August 22, 2005
Updated: February 13, 2007 12:43:38 PM
Type: Trojan Horse
Systems Affected: Windows

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Disable System Restore (Windows Me/XP).
  2. Remove all the entries that the risk added to the hosts file.
  3. Update the virus definitions.
  4. Run a full system scan and delete all the files detected.
  5. Delete any values added to the registry.
For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article: Antivirus Tools Cannot Clean Infected Files in the _Restore Folder (Article ID: Q263455).

2. To remove all the entries that the risk added to the hosts file
  1. Navigate to the following location:

    • Windows 95/98/Me:
    • Windows NT/2000/XP:

    • The location of the hosts file may vary and some computers may not have this file. There may also be multiple copies of this file in different locations. If the file is not located in these folders, search your disk drives for the hosts file, and then complete the following steps for each instance found.
    • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows (Windows 95/98/Me/XP) or C:\Winnt (Windows NT/2000).

  2. Double-click the hosts file.
  3. If necessary, deselect the "Always use this program to open this program" check box.
  4. Scroll through the list of programs and double-click Notepad.
  5. When the file opens, delete all the entries added by the risk. (See the Technical Details section for a complete list of entries.)
  6. Close Notepad and save your changes when prompted.

3. To update the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to Virus Definitions (Intelligent Updater).

    The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions. For detailed instructions read the document: How to update virus definition files using the Intelligent Updater.

4. To scan for and delete the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected, click Delete.

Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do this, run the scan in Safe mode. For instructions, read the document, How to start the computer in Safe Mode . Once you have restarted in Safe mode, run the scan again.

After the files are deleted, restart the computer in Normal mode and proceed with the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

Title: [FILE PATH]
Message body: Windows cannot find [FILE NAME]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.

5. To delete the value from the registry
Important: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified subkeys only. For instructions refer to the document: How to make a backup of the Windows registry.
  1. Click Start > Run.
  2. Type regedit
  3. Click OK.

    Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.

  4. Navigate to the subkey:


  5. In the right pane, delete the value:

    "svshost" = "%System%\[RANDOM NAME]\svshost.exe"

  6. Exit the Registry Editor.

Writeup By: Rodney Andres