Discovered: June 10, 2004
Updated: February 13, 2007 12:24:19 PM
Also Known As: W32/Zafi.b@MM [McAfee], Zafi.B [Computer Associates], W32/Zafi-B [Sophos], PE_ZAFI.B [Trend]
Type: Worm
Systems Affected: Windows

W32.Erkez.B@mm is a mass-mailing worm that sends itself to the email addresses found on an infected computer. It also copies itself to the folders that are likely to be shared on file-sharing networks.

When this worm infects a computer, it attempts to overwrite .exe files. The files that it targets are usually executables that belong to security products, including Symantec products. However, in some cases, the worm may overwrite .exe files that belong to other programs.

If the worm does overwrite .exe files, some programs or operating system functions may no longer work correctly.

This threat is compressed with FSG.

The worm does not have a static MD5 value.

Antivirus Protection Dates

  • Initial Rapid Release version June 11, 2004
  • Latest Rapid Release version March 23, 2017 revision 037
  • Initial Daily Certified version June 11, 2004
  • Latest Daily Certified version March 23, 2017 revision 041
  • Initial Weekly Certified release date June 13, 2004

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

Technical Description

When W32.Erkez.B@mm runs, it does the following:

  1. Creates the mutex "_Hazafibb," which allows only one instance of the worm to run in memory.

  2. Copies itself to the %System% folder as:
    • An eight-character, random file name with a .exe extension
    • An eight-character, random file name with a .dll extension.

      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).

  3. Creates some files in the %System% folder. These files have an eight-character, random file name with a .dll extension.

  4. Creates the registry key:


  5. Adds the value:

    "_Hazafibb"="%system%\<random file name>.exe"

    to the registry key:


    so that the worm runs when you start Windows.

  6. Searches for folders that are likely to be shared on file-sharing networks. (It looks for folders on drives C through H whose name contains "share" or "upload.")

  7. Copies itself to the folders that it finds as one of the following:
    • winamp 7.0 full_install.exe
    • Total Commander 7.0 full_install.exe

  8. Opens the browser and loads a page that is randomly selected from the values in the following registry key:

    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TypedURLs

  9. Checks for an active Internet connection by querying one of the following:

  10. Sends numerious HTTP Get requests to the following Web sites to perform Denial of Service (DoS) attacks:

  11. Prevents users from running applications that contain any of the following strings:
    • regedit
    • msconfig
    • task

  12. Searches the computer for the files or folders that belong to known security products, including Symantec products:
    • If the worm finds such a file, the worm will overwrite it with a copy of itself.
    • If the worm finds such a folder, the worm will overwrite all .exe files in that folder and in any subfolders with a copy of itself. As a result, the worm will overwrite .exe files in the following folders and in their subfolders:
      • C:\Program Files\Symantec
      • C:\Program Files\Norton AntiVirus

        Note: The worm is not limited to the above folders, and may overwrite the files in other locations.

  13. Retrieves the email addresses from the Windows Address Book files.

  14. Searches for the email addresses in all the files that have these extensions:
    • .htm
    • .wab
    • .txt
    • .dbx
    • .tbb
    • .asp
    • .php
    • .sht
    • .adb
    • .mbx
    • .eml
    • .pmr

      However, it does not copy the email addresses that contain these substrings:
    • admi
    • cafee
    • google
    • help
    • hotm
    • info
    • kasper
    • micro
    • msn
    • panda
    • sopho
    • suppor
    • syma
    • trend
    • use
    • vir
    • webm
    • win
    • yaho

  15. Stores these email addresses in the .dll files that it created in %System%. (See step 3.)

  16. Uses its own SMTP engine to send itself to the email addresses that it finds.

    The worm will send the email message, written in English, to all the domains except for the following:

    For the domains listed above, the email message will be in the local language.

    For example, if the email address that the worm sends is a message to, the email message will be in Swedish; a message sent to will be in English.

    The email has the following characteristics:

    From: The "From:" field of the email is spoofed.

    The rest of the email will be one of the following (depending on domain name of the email address):

    Subject: <Blank>
    Attachment: <random file name with .com, .exe, or .pif as extension>
    Message: <random>

    To: Anita
    Subject: Ingyen SMS!
    Attachment: "regiszt.php?3124freesms.index777.pif"
    ------------------------ hirdet=E9s -----------------------------
    A sikeres =E9s az t=E1mogat=E1s=E1val =FAjra
    indul az ingyenes sms k=FCld=F5 szolg=E1ltat=E1s! Jelenleg ugyan
    korl=E1tozott sz=E1mban, napi 20 ingyen smst lehet felhaszn=E1lni.
    K=FCldj te is SMST! Neh=E1ny kattint=E1s =E9s a mell=E9kelt regisztr=E1ci=F3s
    lap kit=F6lt=E9se ut=E1n azonnal ig=E9nybevehet=F5! B=F5vebb inform=E1ci=F3t
    a oldalon tal=E1lsz, de siess, mert az els=F5 ezer
    felhaszn=E1l=F3 k=F6z=F6tt =E9rt=E9kes nyerem=E9nyeket sorsolunk ki!
    ------------------------ ---------------------------

    To: Claudia
    Subject: Importante!
    Attachment: "link.informacion.phpV23.text.message.pif"
    Informacion importante que debes conocer, -

    To: Katya
    Subject: oKatya
    Attachment: ""

    To: Eva
    Subject: E-Kort!
    Attachment: "link.ekort.index.phpV7ab4.kort.pif"
    Message: Mit hjerte banker for dig!

    To: Marica
    Subject: Ecard!
    Attachment: "link.showcard.index.phpAv23.ritm.pif"
    De cand te-am cunoscut inima mea are un nou ritm!

    To: Anna
    Subject: E-vykort!
    Attachment: "link.vykort.showcard.index.phpBn23.pif"
    Message: Till min Alskade...

    To: Erica
    Subject: E-Postkort!
    Attachment: "link.postkort.showcard.index.phpAe67.pif"
    Message: Vakre roser jeg sammenligner med deg...

    To: Katarina
    Subject: E-postikorti!
    Attachment: "link.postikorti.showcard.index.phpGz42.pif"
    Message: Iloista kesaa!

    To: Magdolina
    Subject: Atviruka!
    Attachment: "link.atviruka.showcard.index.phpGz42.pif"
    Message: Linksmo gimtadieno! ha

    To: Beate
    Subject: E-Kartki!
    Attachment: "link.kartki.showcard.index.phpVg42.pif"
    Message: W Dniu imienin...

    To: Eva
    Subject: Cartoe Virtuais!
    Attachment: "link.cartoe.viewcard.index.phpYj39.pif"
    Message: Content: Te amo... ,

    To: Alice
    Subject: Flashcard fuer Dich!
    Attachment: ""
    hat dir eine elektronische Flashcard geschickt.
    Um die Flashcard ansehen zu koennen, benutze in deinem Browser
    einfach den nun folgenden link:
    http:/ /
    Viel Spass beim Lesen wuenscht Ihnen ihr...

    To: Eva
    Subject: Er staat een eCard voor u klaar!
    Attachment: ""
    heeft u een eCard gestuurd via de website nederlandse
    taal in het basisonderwijs...
    U kunt de kaart ophalen door de volgende url aan te klikken of te
    kopiren in uw browser link:
    http:/ /
    Met vriendelijke groet,
    De redactie taalsite primair onderwijs...

    To: Hanka
    Subject: Elektronicka pohlednice!
    Attachment: ""
    Elektronick pohlednice ze serveru http:/ / -

    To: Claudine
    Subject: E-carte!
    Attachment: ""
    vous a envoye une E-carte partir du site
    Vous la trouverez, l'adresse suivante link:
    http:/ /, plus de 3500 cartes virtuelles, vos pages web
    en 5 minutes, du dialogue en direct...

    To: Francesca
    Subject: Ti e stata inviata una Cartolina Virtuale!
    Attachment: ""
    ha visitato il nostro sito, e ha creato una
    cartolina virtuale per te! Per vederla devi fare click
    sul link sottostante: http:/ /
    Attenzione, la cartolina sara visibile sui nostri server per
    2 giorni e poi verra rimossa automaticamente.

    To: Jennifer
    Subject: You`ve got 1 VoiceMessage!
    Attachment: ""
    Dear Customer!
    You`ve got 1 VoiceMessage from website!
    You can listen your Virtual VoiceMessage at the following link:
    http:/ /
    or by clicking the attached link.
    Send VoiceMessage! Try our new virtual VoiceMessage Empire!
    Best regards: SNAF.Team (R).

    To: Anita
    Subject: Tessek mosolyogni!!!
    Attachment: "meztelen csajok fociznak.flash.jpg.pif"
    Ha ez a k=E9p sem tud felviditani, akkor feladom!
    Sok puszi:

    To: Anita
    Subject: Soxor Csok!
    Attachment: "anita.image043.jpg.pif"
    Aranyos vagy, j=F3 volt dumcsizni veled a neten!
    Rem=E9lem tetszem, =E9s szeretn=E9m ha te is k=FClden=E9l k=E9pet
    magadr=F3l, addig is cs=F3k:

    To: Jennifer
    Subject: Don`t worry, be happy!
    Attachment: ""
    Hi Honey!
    I`m in hurry, but i still love ya...
    (as you can see on the picture)
    Bye - Bye:

    To: David
    Subject: Check this out kid!!!
    Attachment: "jennifer the wild girl xxx07.jpg.pif"
    Send me back bro, when you`ll be done...(if you know what i mean...)
    See ya,


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.


Removal using the W32.Erkez.B@mm Removal Tool
Use the W32.Erkez.B@mm removal tool first, as it is the easiest way to remove this threat.

Manual Removal
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. Update the virus definitions.
  3. Restart the computer in Safe mode or VGA mode.
  4. Run a full system scan and delete all the files detected as W32.Erkez.B@mm.
  5. Reverse the changes made to the registry.
For specific details on each of these steps, read the following instructions.

Important: Alternate steps if the worm has already run.
If the worm has already run, it may have overwritten files that Symantec AntiVirus and Norton AntiVirus products require. If you cannot start your Norton or Symantec antivirus product in steps 2 or 4, follow this alternate procedure:
  1. Restart in Safe mode or VGA mode (step 3.).
  2. Edit the registry (step 5).
  3. Restart in Normal mode.
  4. Re-install Symantec AntiVirus or Norton AntiVirus.
  5. Follow steps 1 through 5.

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:
Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable 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 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 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.

3. To restart the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.
  • For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
  • For Windows NT 4 users, restart the computer in VGA mode.

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 as infected with W32.Erkez.B@mm, click Delete.

5. To reverse the changes made to the registry

WARNING: 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 > 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 value that refers to the worm file.

  5. Navigate to the key and delete it:


  6. Exit the Registry Editor.

  7. Restart the computer in Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."

Writeup By: Yana Liu