Discovered: November 19, 2004
Updated: February 13, 2007 12:30:07 PM
Also Known As: Win32.Sober.I [Computer Associ, Sober.I [F-Secure], I-Worm.Sober.i [Kaspersky], W32/Sober.j@MM [McAfee], W32/Sober.I@mm [Norman], W32/Sober.I.worm [Panda], W32/Sober-I [Sophos], WORM_SOBER.I [Trend]
Type: Worm
Systems Affected: Windows

W32.Sober.I@mm is a mass-mailing worm that uses its own SMTP engine to spread by sending itself as an email attachment to the addresses gathered from the infected computer.

The subject of the email varies and will be in either English or German. The email sender address is spoofed. The name of the email attachment varies and has a .bat, .com, .pif, .scr, or .zip extension. The attachment may also have a double file extension.

This threat is written in the Microsoft Visual Basic programming language and is compressed with UPX.


  • Live Update definitions version 61119c (extended version 11/19/2004 rev. 3) or greater will detect this threat.
  • In certain circumstances the worm may corrupt itself. If this happens the worm will not execute on the computer and antivirus software may not be able to detect it. A computer is infected with a corrupt version of W32.Sober.I@mm may display Command Prompt windows when Windows starts.
  • The W32.Sober@mm Removal Tool will not be able to uninstall corrupt versions of W32.Sober.I@mm. Use the manual removal instructions listed below in these cases.

Antivirus Protection Dates

  • Initial Rapid Release version November 19, 2004
  • Latest Rapid Release version April 26, 2019 revision 005
  • Initial Daily Certified version November 19, 2004
  • Latest Daily Certified version April 26, 2019 revision 006
  • Initial Weekly Certified release date November 19, 2004

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

Technical Description

When W32.Sober.I@mm is executed, it performs the following actions:

  1. Displays the following message:

    "WinZip_Data_Module is missing ~Error: {[random number]}"

  2. Creates two files in the %System% folder using a file name composed of the following strings:

    • sys
    • host
    • dir
    • expoler
    • win
    • run
    • log
    • 32
    • disc
    • crypt
    • data
    • diag
    • spool
    • service
    • smss32

      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. Creates the following files:

    • %System%\nonzipsr.noz
    • %System%\clonzips.ssc
    • %System%\clsobern.isc
    • %System%\sb2run.dii
    • %System%\winsend32.dal
    • %System%\winroot64.dal
    • %System%\zippedsr.piz
    • %System%\winexerun.dal
    • %System%\winmprot.dal
    • %System%\dgssxy.yoi
    • %System%\cvqaikxt.apk
    • %System%\sysmms32.lla
    • %System%\Odin-Anon.Ger

  4. Adds the values:

    "[random value name]" = "%System%\[random worm file name].exe"
    "[random value name]" = "%System%\[random worm file name].exe %srun%"

    to the registry key:


    so that the worm is executed every time Windows starts.

    Note: [random value name] is composed of one or more of the following strings:

    • sys
    • host
    • dir
    • expoler
    • win
    • run
    • log
    • 32
    • disc
    • crypt
    • data
    • diag
    • spool
    • service
    • smss32

  5. If the current date has passed January 5, 2005, then the worm may attempt to download and execute a file from multiple locations on the following domains:


      This file is detected as Trojan.Dimi.

  6. Gathers email addresses from files on the infected computer.

    It avoids the email addresses that contain the following strings:

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

  7. Checks the network connection by contacting an NTP server on TCP port 37, or by resolving one of the following domains:


  8. Sends a copy of itself as an email attachment to the addresses that it finds on the infected computer, using its own SMTP Engine. The email messages will be in either English or German and will have the following characteristics:

    The From line can be an email address found on the infected computer or comprised of the following:

    [fake sender name]@[recipient's domain]

    where [fake sender name] is one of the following:

    • Info
    • FehlerMail
    • Webmaster
    • ReMailer
    • Lisa
    • Peter
    • Michael
    • Thomas
    • Elke
    • Susi
    • Nadine
    • Benutzer-Daten
    • Information
    • Service
    • Hilfe
    • Webmaster
    • Hostmaster
    • Postmaster
    • User-Info

      and [recipient's domain] is the domain of the intended receiver of the email.

      Subject: One of the following:

    • FwD: hi there
    • FwD: hey dude!
    • FwD: wazzup!!!
    • FwD: yeah dude :P
    • FwD: Details
    • FwD: Oh God it's
    • FwD: damn!
    • FwD: #
    • FwD: Registration confirmation
    • FwD: Confirmation
    • FwD: Your Password
    • FwD: Your mail account
    • FwD: Delivery failure notice
    • FwD: Faulty mail delivery
    • FwD: Mail delivery failed
    • FwD: Mailing Error
    • FwD: Illegal signs in E-Mail
    • FwD: Invalid mail length
    • FwD: Mail Delivery failure
    • FwD: mail delivery status
    • FwD: Warning!
    • FwD: error in dbase
    • FwD: DBase Error
    • FwD: ups, i've got your mail
    • FwD: Sorry, that's your mail
    • FwD: why do you do that?
    • FwD: Life's a Bitch
    • FwD: Smiling Like a Killer
    • FwD: lol,wat'nlosey?
    • FwD: Informationvon
    • FwD: FalscheMailzustellung
    • FwD: FehlerinIhrerE-Mail
    • FwD: IhreE-Mailwarfehlerhaft
    • FwD: ESMTPError
    • FwD: UngültigeVariableninihrerE-Mail
    • FwD: Verbindungwurdegetrennt
    • FwD: Mail_Fehler
    • FwD: IhrneuerAccount
    • FwD: NeueAccountDaten
    • FwD: Siehabennichtgezahlt
    • FwD: Rechnung
    • FwD: Hi,seivorsichtig!
    • FwD: Achtung!gefährlicherVirus!
    • FwD: Schongehört?
    • FwD: DieTools!
    • FwD: DeinZeug's!
    • FwD: Hierfürdich^^
    • FwD: BestellungsBestätigung
    • FwD: Lieferungs-Bestätigung
    • FwD: Ok,hieristmein
    • FwD: Ichhabemichindichv

      Body: May be composed of some of the following text:

      ++++ User-Service: http:/ /www.<sender's domain>
      ++++ MailTo: postmaster@<sender's domain>

      Your password was changed successfully.

      Protected message is attached.

      This account_hast_been_disabled.


      Diese Information ist geschützt duch ein Passwort!

      Da Sie uns Ihre Persönlichen Daten zugesandt haben, ist das Passwort Ihr Geburts-Datum.

      Viel vergnügen mit unserem Angebot!

      Im I-Net unter: http:www.[domain]

      Aus Datenschutzrechtlichen Gründen, darf die vollständige E'Mail incl. Daten nur angehängt werden.

      Wir bitten Sie, dieses zu berücksichtigen.

      GmBH & Co. KG

      Da unsere Datenbanken leider durch einen Programm Fehler zerstört wurden, mussten wir leider eine änderung bezüglich Ihrer Nutzungs- Daten vornehmen.
      Ihre geänderten Account Daten, befinden sich im beigefügten Dokument.


      This mail was generated automatically.
      More info about --GAYNET-- under: http:/ /


      # 440: MAILBOX NOT FOUND


      The full mail is attached.

      Auto_Mail.System: [gaynet]

      *-*-* Mail_Scanner: No Virus
      *-*-* SYMANTEC- Anti_Virus Service


      I was surprised, too!
      Who_could_suspect_something_like_that? sh*tyiiiii


      --------------This mail was generated automatically.
      More info about --HOTMAIL-- under: http:/ /


      # 153: Giving_up_on_[IP]


      The full mail is attached.

      Auto_Mail.System: [hotmail]

      *-*-* Mail_Scanner: No Virus
      *-*-* SYMANTEC- Anti_Virus Service

      The attachment may be based on an email address found on the infected computer or may be one of the following, with a .pif, .zip, .scr, .bat or .com extension:

    • im_shocked
    • oh_nono
    • thats_hard
    • mail
    • auto_mail
    • re-mail_system
    • Error_mail

      The attachment may also be named [recipient's domain].[first extension].zip where [first extension] is one of the following:

    • .txt
    • .doc
    • .word
    • .xls
    • .eml
    • .TXT
    • .DOC
    • .EML


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 Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Sober.I@mm. Try this removal tool first, as it is the easiest way to remove this threat.

Manual Removal Instructions
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. Run a full system scan and delete all the files detected as W32.Sober.I@mm.
  4. Delete the value that was 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, 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 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 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 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.Sober.I@mm, click Delete.

    If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix 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, you can leave the computer in Safe mode and proceed with section 4. When that is done, restart the computer in Normal mode.)

4. To delete the value from the registry

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.
  2. Type regedit

    Then click OK.

  3. Navigate to the key:


  4. In the right pane, delete the value:

    "[random value name]" = "%System%\[random worm file name].exe"
    "[random value name]" = "%System%\[random worm file name].exe %srun%"

  5. Exit the Registry Editor.

Writeup By: Candid Wueest