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Discovered: January 07, 2003
Updated: February 13, 2007 11:42:06 AM
Also Known As: Trojan.Win32.KKiller [KAV]
Type: Trojan Horse
Systems Affected: Windows

The Trojan.KKiller Trojan Horse terminates many processes, including those of popular antivirus and firewall programs. It also modifies a registry key, so that it runs when you try to execute any .exe file.

Trojan.KKiller is written in the Delphi programming language and is packed with UPX.

Antivirus Protection Dates

  • Initial Rapid Release version January 07, 2003
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version January 07, 2003
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date January 08, 2003

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

Technical Description

When Trojan.KKiller is executed, it does the following:

  1. Copies itself as %Windir%\<Trojan file name.exe>.

    NOTE: %Windir% is a variable. The Trojan locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.
  2. Modifies the (Default) value of the registry key:



    <Trojan file name.exe> "%1" %*
  3. Terminates the following processes:
    • _Avp32.exe
    • _avpcc.exe
    • _avpm.exe
    • Ackwin32.exe
    • Advxdwin.exe
    • Ahnsd.exe
    • Alertsvc.exe
    • Alogserv.exe
    • Amon9x.exe
    • Anti-trojan.exe
    • Apvxdwin.exe
    • Atcon.exe
    • Atupdater.exe
    • Atwatch.exe
    • Autodown.exe
    • Autotrace.exe
    • Avconsol.exe
    • Avgcc32.exe
    • Avgctrl.exe
    • Avgserv.exe
    • Avgserv9.exe
    • Avgw.exe
    • Avkpop.exe
    • Avkserv.exe
    • Avkservice.exe
    • Avkwctl9.exe
    • Avp32.exe
    • Avpcc.exe
    • Avpexec.exe
    • Avpinst.exe
    • Avpm.exe
    • Avpupd.exe
    • Avrescue.exe
    • Avsched32.exe
    • Avsynmgr.exe
    • Avwinnt.exe
    • Avxmonitor9x.exe
    • Avxmonitornt.exe
    • Avxquar.exe
    • Avxw.exe
    • Blackd.exe
    • Blackice.exe
    • Cdp.exe
    • Claw95.exe
    • Claw95cf.exe
    • Cleaner.exe
    • Cleaner3.exe
    • Cmgrdian.exe
    • Connectionmonitor.exe
    • Cpd.exe
    • Csinject.exe
    • Csinsm32
    • Css 1631.exe
    • Defscangui.exe
    • Defwatch.exe
    • Doors.exe
    • Dvp95.exe
    • Dvp95_0.exe
    • Efpeadm.exe
    • Etrustcipe.exe
    • Evpn.exe
    • Expert.exe
    • F-agnt95.exe
    • Fameh32.exe
    • Fch32.exe
    • Fih32.exe
    • Fix-it.exe
    • Fnrb32.exe
    • F-prot.exe
    • F-prot95.exe
    • Fp-win.exe
    • Frw.exe
    • Fsaa.exe
    • Fsav32.exe
    • Fsave32.exe
    • Fsgk32.exe
    • Fsm32.exe
    • Fsma32.exe
    • Fsmb32.exe
    • F-stopw.exe
    • Fwenc.exe
    • Gbmenu.exe
    • Gbpoll.exe
    • Generics.exe
    • Guard.exe
    • Guarddog.exe
    • Iamapp.exe
    • Iamserv.exe
    • Icload95.exe
    • Icloadnt.exe
    • Icmon.exe
    • Icsupp95.exe
    • Icsuppnt.exe
    • Iface.exe
    • Iomon98.exe
    • Isrv95.exe
    • Jammer.exe
    • Jedi.exe
    • Ldnetmon.exe
    • Ldpromenu.exe
    • Ldscan.exe
    • Lockdown.exe
    • Luall.exe
    • Lucomserver.exe
    • Mcagent.exe
    • Mcmnhdlr.exe
    • Mcshield
    • Mcshield.exe
    • Mctool.exe
    • Mcupdate.exe
    • Mcvsrte.exe
    • Mcvsshld.exe
    • Mgavrtcl.exe
    • Mgavrte.exe
    • Mghtml.exe
    • Minilog.exe
    • Monitor.exe
    • Monsys32.exe
    • Monsysnt.exe
    • Monwow.exe
    • Moolive.exe
    • Mwatch.exe
    • Mxtask.exe
    • Navapsvc.exe
    • Navapw32.exe
    • Navdx.exe
    • Navlu32.exe
    • Navrunr.exe
    • Navw32.exe
    • Navwnt.exe
    • Ndd32.exe
    • Neowatchlog.exe
    • Netutils.exe
    • Nisserv.exe
    • Nisum.exe
    • Nmain.exe
    • Normist.exe
    • Nprotect.exe
    • Npssvc.exe
    • Nsched32.exe
    • Ntaskmgr.exe
    • Ntrtscan.exe
    • Ntvdm.exe
    • Ntxconfig.exe
    • Nui.exe
    • Nvc95.exe
    • Nvlaunch.exe
    • Nwservice.exe
    • Nwtool16.exe
    • Offguard.exe
    • Padmin.exe
    • Pavproxy.exe
    • Pccclient.exe
    • Pccguide.exe
    • Pcciomon.exe
    • Pccntmon.exe
    • Pccwin97.exe
    • Pccwin98.exe
    • Pcscan.exe
    • Persfw.exe
    • Pop3trap.exe
    • Poproxy.exe
    • Portmonitor.exe
    • Processmonitor.exe
    • Programauditor.exe
    • Protectx.exe
    • Pview95.exe
    • Rav7.exe
    • Rav7win.exe
    • Realmon.exe
    • Rescue.exe
    • Rulaunch.exe
    • Sbserv.exe
    • Scan32.exe
    • Schedapp.exe
    • Scrscan.exe
    • Smc.exe
    • Sphinx.exe
    • Spyxx.exe
    • Srwatch.exe
    • Ss3edit.exe
    • Sweep95.exe
    • Sweepsrv.sys
    • Swnetsup.exe
    • Symproxysvc.exe
    • Symtray.exe
    • Sysdoc32.exe
    • Taumon.exe
    • Tc.exe
    • Tca.exe
    • Tcm.exe
    • Tds-3.exe
    • Tfak.exe
    • Undoboot.exe
    • Vbcmserv.exe
    • Vbcons.exe
    • Vccmserv.exe
    • Vet32.exe
    • Vet95.exe
    • Vettray.exe
    • Vir-help.exe
    • Vpc32.exe
    • Vptray.exe
    • Vsched.exe
    • Vsecomr.exe
    • Vshwin32
    • Vshwin32.exe
    • Vsmain.exe
    • Vsmon.exe
    • Vsstat.exe
    • Vvstat
    • Watchdog.exe
    • Webscanx.exe
    • Webtrap.exe
    • Wgfe95.exe
    • Wimmun32.exe
    • Winroute
    • Winsfcm.exe
    • Wradmin.exe
    • Wrctrl.exe
    • Zapro.exe
    • Zonealarm.exe


    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.


    These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

    • If the Trojan has not yet executed and a scan detects it, delete it when you receive it or try to run it.
    • If the Trojan has run and made changes to your system, perform the following the removal instructions.
    1. Reverse the changes that the Trojan made to the registry.
    2. Update the virus definitions.
    3. Run a full system scan and delete all the files detected as Trojan.KKiller.

    For details on how to do this, read the following instructions.

    Reversing the change made to the registry
    If the Trojan has run, you will not be able to start most programs, including the Symantec antivirus software or LiveUpdate, until you reverse the change it made to the registry. To do this, first make a copy of the Registry Editor (Regedit.exe) as a file with the .com extension, and then run the file.

    Copying Regedit.exe to
    1. Do one of the following, depending on which version of Windows you are running:
      • Windows 95/98 users:
        1. Click Start.
        2. Point to Programs.
        3. Click the MS-DOS Prompt. (A DOS window opens at the C:\Windows prompt.) Proceed to step 2 of this section.
      • Windows Me users:
        1. Click Start.
        2. Point to Programs.
        3. Point to Accessories.
        4. Click the MS-DOS Prompt. (A DOS window opens at the C:\Windows prompt.) Proceed to step 2 of this section.
      • Windows NT/2000 users:
        1. Click Start, and then click Run.
        2. Type command, and then press Enter. (A DOS window opens.)
        3. Type cd \winnt, and then press Enter.
        4. Go to step 2 of this section.
      • Windows XP users:
        1. Click Start, and then click Run.
        2. Type command, and then press Enter. (A DOS window opens.)
        3. Type the following:

          cd \windows

          Press Enter after typing each one.
        4. Proceed to step 2 of this section.
    2. Type copy regedit.exe, and then press Enter.
    3. Type start, and then press Enter. (The Registry Editor will open in front of the DOS window.)

    Editing the registry
    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 the specified keys only. For instructions, read the document, "How to make a backup of the Windows registry ."
    1. Navigate to and select the following key:


      NOTE: The HKEY_CLASSES_ROOT key contains many subkey entries that refer to other file extensions. One of these file extensions is .exe. Changing this extension can prevent any files ending with an .exe extension from running. Make sure that you browse all the way along this path until you reach the \command subkey.

      Modify the HKEY_CLASSES_ROOT\exefile\shell\open\command subkey, shown in the following figure:

      <<=== NOTE: Modify this key.
    2. In the right pane, double-click the (Default) value.
    3. Delete the current value data, and then type: "%1" %* (That is, type the characters: quote-percent-one-quote-space-percent-asterisk.).

      • Under Windows 95/98/Me/NT, the Registry Editor automatically encloses the value within quotation marks. When you click OK, the (Default) value should look exactly like this:

        ""%1" %*"  
      • Under Windows 2000/XP, the additional quotation marks will not appear. When you click OK, the (Default) value should look exactly like this:

        "%1" %*
      • Make sure that you completely delete all the value data in the command key before you type the correct data. If you leave a space at the beginning of the entry, any attempt to run the program files will result in the error message, "Windows cannot find .exe." If this occurs, restart the entire process from the beginning of this document and make sure that you completely remove the current value data.
    4. Exit the registry editor.
    Updating 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 the 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 the Virus Definitions (LiveUpdate), in the "Protection" section, at the top of this writeup.
    • Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). 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 the Virus Definitions (Intelligent Updater), in the "Protection" section, at the top of this writeup.

      The 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.

    Scanning for and deleting 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 as infected with Trojan.KKiller, click Delete.

    Writeup By: Kaoru Hayashi