Discovered: November 19, 2005
Updated: February 13, 2007 12:46:35 PM
Also Known As: CME-681, WORM_SOBER.AG [Trend Micro], W32/Sober-{X, Z} [Sophos], Win32.Sober.W [Computer Associ, Sober.Y [F-Secure], W32/Sober@MM!M681 [McAfee], W32/Sober.AA@mm [Norman], Win32/Sober.Z@mm [Microsoft]
Type: Worm
Systems Affected: Windows

W32.Sober.X@mm is a mass-mailing worm that uses its own SMTP engine to spread and lowers security settings. It sends itself as an email attachment to addresses gathered from the compromised computer. The email may be in either English or German.

Note: Symantec products that support the Worm Blocking functionality automatically detect this threat as it attempts to spread.

Antivirus Protection Dates

  • Initial Rapid Release version November 19, 2005
  • Latest Rapid Release version July 18, 2019 revision 021
  • Initial Daily Certified version November 19, 2005
  • Latest Daily Certified version July 19, 2019 revision 002
  • Initial Weekly Certified release date November 22, 2005

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

Technical Description

When executed, W32.Sober.X@mm performs the following actions:

  1. Displays a message with the following text:

    Title: WinZip Self-Extractor
    Body: Error in packed Header

  2. Copies itself as the following files:

    • %Windir%\WinSecurity\csrss.exe
    • %Windir%\WinSecurity\services.exe
    • %Windir%\WinSecurity\smss.exe

      Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.

  3. Creates the following files, which are MIME-encoded .zip files that contain a copy of the worm:

    • %Windir%\WinSecurity\socket1.ifo
    • %Windir%\WinSecurity\socket2.ifo
    • %Windir%\WinSecurity\socket3.ifo

  4. Creates the following non-malicious files, which will be used by the worm for email harvesting and as internal flags:

    • %Windir%\WinSecurity\mssock1.dli
    • %Windir%\WinSecurity\mssock2.dli
    • %Windir%\WinSecurity\mssock3.dli
    • %Windir%\WinSecurity\winmem1.ory
    • %Windir%\WinSecurity\winmem2.ory
    • %Windir%\WinSecurity\winmem3.ory
    • %Windir%\WinSecurity\sysonce.tst
    • %Windir%\WinSecurity\
    • %Windir%\WinSecurity\nexttroj.tro

  5. Creates the following zero byte files in an attempt to stop previous versions of the W32.Sober@mm worm from running:

    • %System%\nonrunso.ber
    • %System%\langeinf.lin
    • %System%\filesms.fms
    • %System%\runstop.rst
    • %System%\rubezahl.rub
    • %System%\bbvmwxxf.hml

      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).

  6. Attempts to end the following processes:

    • mrt.exe
    • asw*.tmp

  7. Attempts to end processes that contain any of the following strings:

    • microsoftanti
    • gcas
    • gcip
    • giantanti
    • inetupd.
    • nod32kui
    • nod32.
    • fxsbr
    • avwin.
    • guardgui.
    • aswclnr
    • stinger
    • hijack
    • sober
    • brfix
    • s_t_i_n
    • s-t-i-n

  8. Displays the following message if any of the above processes end:

    Title: Antivirus
    No Viruses, Trojans or Spyware found!
    Status: OK

  9. Retrieves the value of the following subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\LUALL.EXE

    which by default points to %ProgramFiles%\Symantec\LiveUpdate\LUALL.EXE and overwrites the target file with a copy of itself.

    Note: %ProgramFiles% is a variable that refers to the Program Files folder. By default this is C:\Program Files for all Windows versions.

  10. Executes a copy of the worm each time LiveUpdate is launched , and displays one of the following message boxes, depending on the internet connectivity of the compromised computer:

    Title: LiveUpdate   {Symantec}
    Thank you for using LiveUpdate. All of the Symantec
    products and components are currently up-to-date.

    Title: LiveUpdate   {Symantec}
    Body: No Connection!

  11. Removes all the files matching the following name criteria in order to disable LiveUpdate:

    • %ProgramFiles%\Symantec\LiveUpdate\a*.exe
    • %ProgramFiles%\Symantec\LiveUpdate\luc*.exe
    • %ProgramFiles%\Symantec\LiveUpdate\ls*.exe
    • %ProgramFiles%\Symantec\LiveUpdate\luu*.exe

      Note: %ProgramFiles% is a variable that refers to the program files folder. By default, this is C:\Program Files.

  12. Sets a marker, which consists of a byte value located in the worm executable's header, every time the worm copies itself. This marker determines the functionality of each individual copy of the worm. There are five different marker values that signify different actions.

  13. Adds the value:

    " Windows" = "%Windir%\WinSecurity\services.exe"

    to the following registry subkey:


    so that it runs every time Windows starts.

  14. Adds the value:

    "_Windows" = "%Windir%\WinSecurity\services.exe"

    to the following registry subkey:


    so that it runs every time Windows starts.

  15. Adds the value:

    "command" = ""%1" %*"

    to the following registry subkey:


  16. Ends the following service on computers running Windows XP SP2:

    Name: wscsvc
    Display Name: Security Center

    in order to disable the Windows Security Center.

  17. Tries to patch the TCPIP.SYS driver of Windows XP SP2 machine, in the following folders:

    • %System%\drivers\TCPIP.SYS
    • %System%\dllcache\TCPIP.SYS
    • %Windir%\ServicePackFiles\i386\TCPIP.SYS

      Note: The worm is able to patch different versions of the TCPIP.SYS file (build 2180,2505, 2631, 2685) by modifying the checksum of the file and changing the number of allowed half-open connections (a security fix introduced by Microsoft Security Bulleting MS05-019).This change alters the normal functioning of TCP/IP protocol and may cause Network problems.

  18. Attempts to download and execute the following file from the Internet, starting the 6th of January 2006:


    The worm may also attempt to download a file from one of the following domains and save it to %Windir%\WinSecurity\attacke.exe before execution:


      The files to be downloaded will change every week. For example, the following files will be downloaded on Jan 20th, 2006:

    • [http://][REMOVED]/zxh.exe
    • [http://][REMOVED]/nwwod.exe
    • [http://][REMOVED]/kevdw.exe
    • [http://][REMOVED]/buactpcw/dkgo.ayc
    • [http://][REMOVED]/tgktr.exe
    • [http://][REMOVED]/xcd.sax
    • [http://][REMOVED]/atgzj.exe
    • [http://][REMOVED]/upsm.kkp
    • [http://][REMOVED]/vauz.ecpf
    • [http://][REMOVED]/cvmi.xxxc
    • [http://][REMOVED]/yozz.bva
    • [http://][REMOVED]/vvdoo.exe
    • [http://][REMOVED]/aefgm.exe
    • [http://][REMOVED]/ennn.exe
    • [http://][REMOVED]/okfev.exe
    • [http://][REMOVED]/yyu.exe
    • [http://][REMOVED]/yazni.exe
    • [http://][REMOVED]/eddjj.exe
    • [http://][REMOVED]/fusg.daa
    • [http://][REMOVED]/hithv.exe
    • [http://][REMOVED]/ubf.glb
    • [http://][REMOVED]/bfuwz.exe
    • [http://][REMOVED]/zgfv.ttp
    • [http://][REMOVED]/lgtt.ozxt
    • [http://][REMOVED]/eaix.qjee
    • [http://][REMOVED]/yodd.vbw
    • [http://][REMOVED]/cxjza.exe
    • [http://][REMOVED]/lwrdc.exe
    • [http://][REMOVED]/xwww.exe
    • [http://][REMOVED]/vcpoj.exe
    • [http://][REMOVED]/ryl.exe
    • [http://][REMOVED]/mhfasfsi/rhsup.exe
    • [http://][REMOVED]/nhhgg.exe
    • [http://][REMOVED]/mrty.uqm
    • [http://][REMOVED]/uwmud.exe
    • [http://][REMOVED]/cud.ajf
    • [http://][REMOVED]/yzzjc.exe
    • [http://][REMOVED]/ikzfpaoozw/jrhk.iio
    • [http://][REMOVED]/lzxz.lwlx
    • [http://][REMOVED]/wblc.ffdw
    • [http://][REMOVED]/djuu.gyu
    • [http://][REMOVED]/zzgff.exe
    • [http://][REMOVED]/dxmkg.exe
    • [http://][REMOVED]/ghhh.exe
    • [http://][REMOVED]/tpywp.exe

  19. Attempts to use one of the following DNS servers:

  20. Checks the network connection of the compromised computer, and the current date, by connecting to one of the following NTP servers on TCP port 37:


  21. Gathers email addresses from files with the following extensions:

    • .abc
    • .abd
    • .abx
    • .adb
    • .ade
    • .adp
    • .adr
    • .asp
    • .bak
    • .bas
    • .cfg
    • .cgi
    • .cls
    • .cms
    • .csv
    • .ctl
    • .dbx
    • .dhtm
    • .doc
    • .dsp
    • .dsw
    • .eml
    • .fdb
    • .frm
    • .hlp
    • .imb
    • .imh
    • .imh
    • .imm
    • .inbox
    • .ini
    • .jsp
    • .ldb
    • .ldif
    • .log
    • .mbx
    • .mda
    • .mdb
    • .mde
    • .mdw
    • .mdx
    • .mht
    • .mmf
    • .msg
    • .nab
    • .nch
    • .nfo
    • .nsf
    • .nws
    • .ods
    • .oft
    • .php
    • .phtm
    • .pl
    • .pmr
    • .pp
    • .ppt
    • .pst
    • .rtf
    • .shtml
    • .slk
    • .sln
    • .stm
    • .tbb
    • .txt
    • .uin
    • .vap
    • .vbs
    • .vcf
    • .wab
    • .wsh
    • .xhtml
    • .xls
    • .xml

      The worm avoids sending itself to email addresses containing the following strings:

    • -dav
    • .dial.
    • .kundenserver.
    • .ppp.
    • .qmail@
    • .sul.t-
    • @arin
    • @avp
    • @ca.
    • @example.
    • @foo.
    • @from.
    • @gmetref
    • @iana
    • @ikarus.
    • @kaspers
    • @messagelab
    • @nai.
    • @panda
    • @smtp.
    • @sophos
    • @www
    • abuse
    • announce
    • antivir
    • anyone
    • anywhere
    • bellcore.
    • bitdefender
    • clock
    • detection
    • domain.
    • emsisoft
    • ewido.
    • free-av
    • freeav
    • ftp.
    • gold-certs
    • google
    • host.
    • icrosoft.
    • law2
    • linux
    • mailer-daemon
    • mozilla
    • mustermann@
    • nlpmail01.
    • noreply
    • nothing
    • ntp-
    • ntp.
    • ntp@
    • office
    • password
    • postmas
    • reciver@
    • secure
    • service
    • smtp-
    • somebody
    • someone
    • spybot
    • sql.
    • subscribe
    • support
    • t-dialin
    • t-ipconnect
    • test@
    • time
    • user@
    • variabel
    • verizon.
    • viren
    • virus
    • whatever@
    • whoever@
    • winrar
    • winzip
    • you@
    • yourname

  22. Selects an SMTP server from the following list:


  23. Attempts to send a copy of itself to the email addresses gathered using one of the SMTP servers selected above. The email may be in either English or German, and has the following characteristics:


    From: [SPOOFED]

    One of the following:

    • Ihr Passwort
    • Account Information
    • SMTP Mail gescheitert
    • Mailzustellung wurde unterbrochen
    • Ermittlungsverfahren wurde eingeleitet
    • Sie besitzen Raubkopien
    • RTL: Wer wird Millionaer
    • Sehr geehrter Ebay-Kunde

      One of the following:

    • Ihre Nutzungsdaten wurden erfolgreich geaendert. Details entnehmen Sie bitte dem Anhang.
      *** [http://]www.[DOMAIN NAME OF SENDER]
      *** E-Mail: PassAdmin
    • Bei uns wurde ein neues Benutzerkonto mit dem Namen
      Um das Konto einzurichten, benoetigen wir eine Bestaetigung, dass die bei der Anmeldung angegebene e-Mail-Adresse stimmt.
      Bitte senden Sie zur Bestaetigung den ausgefuellten Anhang an uns zurueck.
      Wir richten Ihr Benutzerkonto gleich nach Einlangen der Bestaetigung ein und verstaendigen Sie dann per e-Mail, sobald Sie Ihr Konto benutzen koennen.
      Vielen Dank,
      Ihr Ebay-Team
    • Sehr geehrte Dame, sehr geehrter Herr,
      das Herunterladen von Filmen, Software und MP3s ist illegal und somit strafbar.
      Wir moechten Ihnen hiermit vorab mitteilen, dass Ihr Rechner unter der IP
      erfasst wurde. Der Inhalt Ihres Rechner wurde als Beweismittel sichergestellt und es wird ein Ermittlungsverfahren gegen Sie eingleitet.
      Die Strafanzeige und die Moeglichkeit zur Stellungnahme wird Ihnen in den naechsten Tagen schriftlich zugestellt.
      Aktenzeichen NR.:#
      (siehe Anhang)
      i.A. Juergen Stock
      --- Bundeskriminalamt BKA
      --- Referat LS 2
      --- 65173 Wiesbaden
      --- Tel.: +49 (0)611 - 55 - 12331 oder
      --- Tel.: +49 (0)611 - 55 - 0
    • Glueckwunsch: Bei unserer EMail Auslosung hatten Sie und weitere neun Kandidaten Glueck.
      Sie sitzen demnaechst bei Guenther Jauch im Studio!
      Weitere Details ihrer Daten entnehmen Sie bitte dem Anhang.
      +++ RTL interactive GmbH
      +++ Geschaeftsfuehrung: Dr. Constantin Lange
      +++ Am Coloneum 1
      +++ 50829 Koeln
      +++ Fon: +49(0) 221-780 0 oder
      +++ Fon: +49 (0) 180 5 44 66 99

      One of the following:

    • [STRING 1].zip
    • [STRING 1]
    • [STRING 2].zip
    • Akte[STRING 2].zip
    • [STRING 3].zip
    • [STRING 3]

      where the variable [STRING 1] is one of the following strings:

    • Service
    • Webmaster
    • Postman
    • Info
    • Hostmaster
    • Postmaster
    • Admin

      and the variable [STRING 2] is one of the following strings:

    • Downloads
    • BKA
    • Internet
    • Post
    • Anzeige
    • BKA.Bund

      and the variable [STRING 3] is one of the following strings:

    • Kandidat
    • WWM
    • Auslosung
    • Casting
    • Gewinn
    • Info
    • RTL-Admin
    • RTL
    • Webmaster
    • RTL-TV


      From: [SPOOFED]

      One of the following:

    • Your Password
    • Registration Confirmation
    • smtp mail failed
    • Mail delivery failed
    • hi, ive a new mail address
    • You visit illegal websites
    • Your IP was logged
    • Paris Hilton & Nicole Richie

      One of the following:

    • Account and Password Information are attached!
      Protected message is attached!
      ***** Go to: [http://]www.[DOMAIN NAME OF SENDER]
      ***** Email: postman
    • This is an automatically generated Delivery Status Notification.
      SMTP_Error []
      I'm afraid I wasn't able to deliver your message.
      This is a permanent error; I've given up. Sorry it didn't work out.
      The full mail-text and header is attached!
    • hey its me, my old address dont work at time. i dont know why?!
      in the last days ive got some mails. i' think thaz your mails but im not sure!
      plz read and check ...
    • Dear Sir/Madam,
      we have logged your IP-address on more than 30 illegal answer our questions!
      The list of questions are attached.
      Yours faithfully,
      Steven Allison
      Department Office Admin Mail Post
      ===dkX XbW6dxPbXWPdSDd@R2XL9)CW9)SRd?kx@?
      *** Federal Bureau of Investigation -FBI-
      *** 935 Pennsylvania Avenue, NW, Room 3220
      *** Washington, DC 20535
      ++++ Central Intelligence Agency -CIA-
      ++++ Office of Public Affairs
      ++++ Washington, D.C. 20505
      ++++ phone: (703) 482-0623
      ++++ 7:00 a.m. to 5:00 p.m., US Eastern time
    • The Simple Life:
      View Paris Hilton & Nicole Richie video clips , pictures & more ;)
      Download is free until Jan, 2006!
      Please use our Download manager.

      One of the following:

    • list[RANDOM CHARACTERS].zip
    • question_list[RANDOM CHARACTERS].zip

      The attachment will contain the following file, which is a copy of the worm:



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.Sober@mm Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Sober.X@mm. Use this 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. Reinstall the current version of LiveUpdate
  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 reinstall the current version of LiveUpdate
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:

    " Windows" = "%Windir%\WinSecurity\services.exe"

  6. Navigate to the subkey:


  7. In the right pane, delete the value:

    "_Windows" = "%Windir%\WinSecurity\services.exe"

  8. Navigate to the subkey:


  9. In the right pane, delete the value:

    "command" = ""%1" %*"

  10. Exit the Registry Editor.

Writeup By: Takayoshi Nakayama