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Discovered: May 26, 2003
Updated: February 13, 2007 12:01:41 PM
Also Known As: W32/Naco.b@MM [McAfee], Win32.Naco.B [CA], WORM_NACO.B [Trend], W32/Anacon-B [Sophos], I-Worm.Nocana.b [KAV]
Type: Worm
Systems Affected: Microsoft IIS, Windows

W32.Naco.B@mm is a mass-mailing worm that attempts to spread itself through the email and file-sharing networks. The worm also contains Backdoor functionality and attempts to replace HTML files on the Microsoft IIS server.

This threat is written in the Microsoft Visual Basic (VB) programming language. The VB run-time libraries are required to execute W32.Naco.B@mm.

NOTE : Due to bugs in the code, W32.Naco.B@mm may not properly work.

Antivirus Protection Dates

  • Initial Rapid Release version May 27, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version May 27, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date May 28, 2003

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

Writeup By: Robert X Wang

Discovered: May 26, 2003
Updated: February 13, 2007 12:01:41 PM
Also Known As: W32/Naco.b@MM [McAfee], Win32.Naco.B [CA], WORM_NACO.B [Trend], W32/Anacon-B [Sophos], I-Worm.Nocana.b [KAV]
Type: Worm
Systems Affected: Microsoft IIS, Windows

When W32.Naco.B@mm runs, it may perform some of the following actions:

  1. Copies itself to the %System% folder as some of the following:

    NOTE: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
    • Anacon.exe
    • Build.exe
    • Force.exe
    • Scan.exe
    • Runtime.exe
    • Hangup.exe
    • Hungry.exe
    • Thing.exe
    • Against.exe
    • Wars.exe
    • Syspoly32.exe
    • SysAna32.exe

  2. Adds the values:


    to the registry key:


  3. Adds the value:


    to the registry key:


  4. Adds the value:


    to the registry key:


  5. Adds the values:


    to the registry key:


  6. Attempts to terminate the following processes:
    • Zonealarm.exe
    • Wfindv32.exe
    • Webscanx.exe
    • Vsstat.exe
    • Vshwin32.exe
    • Vsecomr.exe
    • Vscan40.exe
    • Vettray.exe
    • Vet95.exe
    • Tds2-Nt.exe
    • Tds2-98.exe
    • Tca.exe
    • Tbscan.exe
    • Sweep95.exe
    • Sphinx.exe
    • Smc.exe
    • Serv95.exe
    • Scrscan.exe
    • Scanpm.exe
    • Scan95.exe
    • Scan32.exe
    • Safeweb.exe
    • Regedit.exe
    • Rescue.exe
    • Rav7win.exe
    • Rav7.exe
    • Persfw.exe
    • Pcfwallicon.exe
    • Pccwin98.exe
    • Pavw.exe
    • Pavsched.exe
    • Pavcl.exe
    • Padmin.exe
    • Outpost.exe
    • Nvc95.exe
    • Nupgrade.exe
    • Normist.exe
    • Nmain.exe
    • Nisum.exe
    • Navwnt.exe
    • Navw32.exe
    • Navnt.exe
    • Navlu32.exe
    • Navapw32.exe
    • N32scanw.exe
    • Mpftray.exe
    • Moolive.exe
    • Luall.exe
    • Lookout.exe
    • Lockdown2000.exe
    • Jedi.exe
    • Iomon98.exe
    • Iface.exe
    • Icsuppnt.exe
    • Icsupp95.exe
    • Icmon.exe
    • Icloadnt.exe
    • Icload95.exe
    • Ibmavsp.exe
    • Ibmasn.exe
    • Iamserv.exe
    • Iamapp.exe
    • Frw.exe
    • Fprot.exe
    • Fp-Win.exe
    • Findviru.exe
    • f-Stopw.exe
    • f-Prot95.exe
    • f-Prot.exe
    • f-Agnt95.exe
    • Espwatch.exe
    • Esafe.exe
    • Ecengine.exe
    • Dvp95_0.exe
    • Dvp95.exe
    • Cleaner3.exe
    • Cleaner.exe
    • Claw95cf.exe
    • Claw95.exe
    • Cfinet32.exe
    • Cfinet.exe
    • Cfiaudit.exe
    • Cfiadmin.exe
    • Blackice.exe
    • Blackd.exe
    • Avwupd32.exe
    • Avwin95.exe
    • Avsched32.exe
    • Avpupd.exe
    • Avptc32.exe
    • Avpm.exe
    • Avpdos32.exe
    • Avpcc.exe
    • Avp32.exe
    • Avp.exe
    • Avnt.exe
    • Avkserv.exe
    • Avgctrl.exe
    • Ave32.exe
    • Avconsol.exe
    • Autodown.exe
    • Apvxdwin.exe
    • Anti-Trojan.exe
    • Ackwin32.exe
    • _Avpm.exe
    • _Avpcc.exe
    • _Avp32.exe

  7. Stops the Norton AntiVirus Auto-Protect Service.

  8. Removes the Trojan Defense Suite.

  9. Deletes all the files in the C:\SAFEWEB\ folder.

  10. Uses MAPI to email itself to all the contacts in the Windows Address Book. The email has the following characteristics:
    • Subject: (One of the following)
      What New in TechTV!
      Do you happy?
      Great News! Check it out now!
      Just for Laught!
      FoxNews Reporter: Hello! SARS Issue!
      Get Free XXX Web Porn!
      Oh, my girl!
      Crack - Download Accerelator Plus 5.3.9
      Do you remember me?
      The ScreenSaver: Wireless Keyboard
      VBCode: Prevent Your Application From Crack
      Re: are you married?[1]
      Download WinZip 9.0 Beta
      Young and Dangerous 7
      Alert! W32.Anacon.B@mm Worm has been detected!
      Run for your life!
      Update: Microsoft Visual Studio .Net
      Your Password: jad8aadf08
      Tired to Search Anonymous SMTP Server?
    • Attachment:

      NOTE: Due to bugs in the code, the attachment might be missing.
    • Body:
      Hello dear,

      I'm gonna missed you babe, hope we can see again!

      In Love,
      Rekcahlem ~<>~ Anacon

  11. If Microsoft IIS is installed, the worm will create a batch file, ANADEFACE.BAT, to do the following:
    • Rename the following files in the \Inetpub\wwwroot folder of drives C and D:
      "default.asp" -> "ANA_Default.asp"
      "index.htm" -> "ANA_Index.htm"
      "default.htm" -> "ANA_Default.htm"
      "index.html" -> "ANA_Index.html"
      "default.html" -> "ANA_Default.html"
      "index.asp" -> "ANA_Index.asp"
    • Overwrite the original files with the following content:
      I WARN TO YOU! DON'T PLAY STUPID WITH ME! ANACON MELHACKER WILL SURVIVE!, Anacon, Melhacker, Dincracker, PakBrain, Foot-Art and AQTE
      Anacon G0t ya! By Melhacker -dA r34L #4(k3R!
    • Delete all the .log files in the root folders of drives C and D.

  12. Downloads a file from a specified URL.

  13. Steals system information and emails it to chatza@phreaker.net.

  14. Listens on one of the following randomly chosen ports:
    • 5567
    • 45567
    • 36794
    • 7676
    • 2383

  15. Waits for the commands from the hacker to perform the following actions:
    • List/Delete/Execute files
    • List/Kill processes
    • Change display settings
    • Send keys
    • Play AVI and/or WAV files
    • Restart computer
    • Terminates RAS connections
    • Display message
    • Open/Close CD tray
    • Enable/Disable double-click
    • Open/Close clipboard
    • Remove itself
    • Start a keylogger
    • Change wallpaper
    • Hide/Show the system taskbar
    • Swap mouse button
    • Enable/Disable the system hotkey (Ctrl+Alt+Delete)

  16. If the day of the month is the 1st, 4th, 8th, 12th, 16th, 20th, 24th, or 28th, the worm may perform some the following actions:
    1. Drops and runs a reg file, COSN.REG, to:
      • Create the following registry keys:

      • Adds the binary value:


        to the following registry keys:


        NOTE: This will open a share for C:\.

    2. Performs a Denial of Service (DoS) attack on the following IP addresses:

    3. Searches for the following folders:
      • %ProgramFiles%\KMD\My Shared Folder
      • %ProgramFiles%\Kazaa\My Shared Folder
      • %ProgramFiles%\KaZaA Lite\My Shared Folder
      • %ProgramFiles%\Morpheus\My Shared Folder
      • %ProgramFiles%\Grokster\My Grokster
      • %ProgramFiles%\BearShare\Shared
      • %ProgramFiles%\Edonkey2000\Incoming
      • %ProgramFiles%\limewire\Shared

        NOTE: %ProgramFiles% is a variable. By default, this is C:\Program Files.
    4. If the worm finds any of the aforementioned folders, it will copy itself as:
      • The Matrix Evolution.mpg.exe
      • The Matrix Reloaded Preview.jpg.exe
      • Jonny English (JE).avi.exe
      • DOOM III Demo.exe
      • winamp3.exe
      • JugdeDread.exe
      • Microsoft Visual Studio.exe
      • gangXcop.exe
      • Upgrade you HandPhone.exe
      • About SARS Solution.doc.exe
      • Dont eat pork. SARS in there.jpg.exe
      • VISE.exe
      • MSVisual C++.exe
      • QuickInstaller.exe
      • Q111023.exe
      • jdbgmgr.exe
      • WindowsXP PowerToys.exe
      • InternationalDictionary.exe
      • EAGames.exe
      • SEX_HOTorCOOL.exe

    5. Deletes all the files in the root folder.

    6. Formats the D: drive.

NOTE : Due to the bug in the viral code, the worm may not work as the author expected. Instead, it may crash the system.


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: Robert X Wang

Discovered: May 26, 2003
Updated: February 13, 2007 12:01:41 PM
Also Known As: W32/Naco.b@MM [McAfee], Win32.Naco.B [CA], WORM_NACO.B [Trend], W32/Anacon-B [Sophos], I-Worm.Nocana.b [KAV]
Type: Worm
Systems Affected: Microsoft IIS, 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. Reverse the changes that the worm made to the registry and restart the computer.
  3. Update the virus definitions.
  4. Run a full system scan and delete all the files detected as W32.Naco.B@mm.
  5. Reverse the changes that the worm made to IIS.
For specific details on each of these steps, read the following instructions.

1. Disabling System Restore in Windows Me/XP
Users of Windows Me and Windows XP should 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 have backed 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 to restore an infected file on your computer even after you have cleaned the infected files from all the other locations.

Also, in some cases, online scanners may detect a threat in the System Restore folder even if you scanned your computer with an antivirus program and did not find any infected files.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Anti-Virus Tools Cannot Clean Infected Files in the _Restore Folder ," Article ID: Q263455.

2. Reversing the changes made to the registry and restarting the computer

CAUTION : 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 keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. Click Start, and then click Run. (The Run dialog box appears.)
  2. Type regedit

    Then click OK. (The Registry Editor opens.)

  3. Navigate to the key:


  4. In the right pane, delete the values:


  5. Navigate to the key:


  6. In the right pane, delete the value:


  7. Navigate to the key:


  8. In the right pane, delete the value:


  9. Navigate to the key:


  10. In the right pane, delete the values:


  11. Delete the following keys:


  12. Exit the Registry Editor.
  13. Restart computer.

3. 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 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).
  • 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).

    The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

4. 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 W32.Naco.B@mm, click Delete.

5. Reversing the changes that the worm made to IIS
  1. Navigate to the \Inetpub\wwwroot folder
  2. Rename the following files:
    • "ANA_default.asp" -> "default.asp"
    • "ANA_index.htm" -> "index.htm"
    • "ANA_default.htm" -> "default.htm"
    • "ANA_index.html" -> "index.html"
    • "ANA_default.html" -> "default.html"
    • "ANA_index.asp" -> "index.asp"

Writeup By: Robert X Wang