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W32.Rontokbro.D@mm

Category 2
Discovered on: October 12, 2005
Last Updated on: February 02, 2006 11:43:00 AM

W32.Rontokbro.D@mm is a mass-mailing worm that causes system instability.

Also Known As: WORM_RONTOKBRO.C [Trend Micro], Email-Worm.Win32.Brontok.a [Kaspersky]
Type: Worm
Infection Length: 40,928 bytes
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP

protection
  • Virus Definitions (LiveUpdate™ Plus)
  • October 12, 2005

  • Virus Definitions (LiveUpdate™ Daily)
  • October 12, 2005

  • Virus Definitions (LiveUpdate™ Weekly)
  • October 12, 2005

  • Virus Definitions (Intelligent Updater)
  • October 12, 2005

    threat assessment

    Wild

    Threat Metrics

    Low Medium High

    Wild:
    Low

    Damage:
    Medium

    Distribution:
    High

    Damage

    Distribution

    technical details

    When W32.Rontokbro.D@mm is executed, it performs the following actions:

    1. Copies itself as the following files:

      • %UserProfile%\Local Settings\Application Data\csrss.exe
      • %UserProfile%\Local Settings\Application Data\inetinfo.exe
      • %UserProfile%\Local Settings\Application Data\lsass.exe
      • %UserProfile%\Local Settings\Application Data\services.exe
      • %UserProfile%\Local Settings\Application Data\smss.exe
      • %UserProfile%\Local Settings\Application Data\winlogon.exe
      • %UserProfile%\Start Menu\Programs\Startup\Empty.pif
      • %UserProfile%\Templates\WowTumpeh.com
      • %Windir%\eksplorasi.pif
      • %Windir%\ShellNew\bronstab.exe
      • %System%\[user name]'s Setting.scr

        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).
      • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows (Windows 95/98/Me/XP) or C:\Winnt (Windows NT/2000).
      • %UserProfile% is a variable that refers to the current user's profile folder. By default, this is C:\Documents and Settings\[CURRENT USER] (Windows NT/2000/XP).

    2. Creates the directory:

      %UserProfile%\Local Settings\Application Data\Bron.tok-[X]-[Y]

      Where [X],[Y] are two random numbers.

    3. Overwrites C:\Autoexec.bat with the following text:

      "pause"

    4. Adds the value:

      "Bron-Spizaetus" = "%Windir%\ShellNew\bronstab.exe"

      to the registry subkey:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

      so that it runs every time Windows starts.

    5. Adds the value:

      "NoFolderOptions" = "1"

      to the registry subkey:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer

    6. Adds the value:

      "Hidden" = "0"
      "ShowSuperHidden" = "0"
      "HideFileExt" = "1"



      to the registry subkey:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\explorer\advanced

    7. Adds the values:

      "DisableRegistryTools" = "1"
      "DisableCMD" = "0"


      to the registry subkey:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System

    8. Adds the value:

      "Tok-Cirrhatus" = "%UserProfile%\Local Settings\Application Data\smss.exe"

      to the registry subkey:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

      so that it runs every time Windows starts.

    9. Adds the value:

      "Shell" = "Explorer.exe %Windir%\eksplorasi.pif"

      to the registry subkey:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

      so that it runs every time Windows starts.
    10. Adds a task to the Windows scheduler to execute the following file at 5:08 PM every day:

      %Windir\Tasks\At1.job

    11. Restarts the computer when it detects a window whose title contains one of the following strings:

      • ..
      • .@
      • @.
      • .ASP
      • .EXE
      • .HTM
      • .JS
      • .PHP
      • ADMIN
      • ADOBE
      • AHNLAB
      • ALADDIN
      • ALERT
      • ALWIL
      • ANTIGEN
      • APACHE
      • APPLICATION
      • ARCHIEVE
      • ASDF
      • ASSOCIATE
      • AVAST
      • AVG
      • AVIRA
      • BILLING@
      • BLACK
      • BLAH
      • BLEEP
      • BUILDER
      • CANON
      • CENTER
      • CILLIN
      • CISCO
      • CMD.
      • CNET
      • COMMAND
      • COMMAND PROMPT
      • CONTOH
      • CONTROL
      • CRACK
      • DARK
      • DATA
      • DATABASE
      • DEMO
      • DETIK
      • DEVELOP
      • DOMAIN
      • DOWNLOAD
      • ESAFE
      • ESAVE
      • ESCAN
      • EXAMPLE
      • FEEDBACK
      • FIREWALL
      • FOO@
      • FUCK
      • FUJITSU
      • GATEWAY
      • GOOGLE
      • GRISOFT
      • GROUP
      • HACK
      • HAURI
      • HIDDEN
      • HP.
      • IBM.
      • INFO@
      • INTEL.
      • KOMPUTER
      • LINUX
      • LOG OFF WINDOWS
      • LOTUS
      • MACRO
      • MALWARE
      • MASTER
      • MCAFEE
      • MICRO
      • MICROSOFT
      • MOZILLA
      • MYSQL
      • NETSCAPE
      • NETWORK
      • NEWS
      • NOD32
      • NOKIA
      • NORMAN
      • NORTON
      • NOVELL
      • NVIDIA
      • OPERA
      • OVERTURE
      • PANDA
      • PATCH
      • POSTGRE
      • PROGRAM
      • PROLAND
      • PROMPT
      • PROTECT
      • PROXY
      • RECIPIENT
      • REGISTRY
      • RELAY
      • RESPONSE
      • ROBOT
      • SCAN
      • SCRIPT HOST
      • SEARCH R
      • SECURE
      • SECURITY
      • SEKUR
      • SENIOR
      • SERVER
      • SERVICE
      • SHUT DOWN
      • SIEMENS
      • SMTP
      • SOFT
      • SOME
      • SOPHOS
      • SOURCE
      • SPAM
      • SPERSKY
      • SUN.
      • SUPPORT
      • SYBARI
      • SYMANTEC
      • SYSTEM CONFIGURATION
      • TEST
      • TREND
      • TRUST
      • UPDATE
      • UTILITY
      • VAKSIN
      • VIRUS
      • WINDOWS SECURITY.VBS
      • W3.
      • WWW
      • XEROX
      • XXX
      • YOUR
      • ZDNET
      • ZEND
      • ZOMBIE


    12. Gathers email addresses from files with the following extensions on all local drives from C to Y:

      • ASP
      • CFM
      • CSV
      • DOC
      • EML
      • HTML
      • PHP
      • TXT
      • WAB

    13. Does not send itself to email addresses that contain any of the following strings in the domain name:

      • PLASA
      • TELKOM
      • INDO
      • .CO.ID
      • .GO.ID
      • .MIL.ID
      • .SCH.ID
      • .NET.ID
      • .OR.ID
      • .AC.ID
      • .WEB.ID
      • .WAR.NET.ID
      • ASTAGA
      • GAUL
      • BOLEH
      • EMAILKU
      • SATU

    14. May append the following prefixes to domain names in an attempt to find Simple Mail Transfer Protocol (SMTP) servers:

      • smtp.
      • mail.
      • ns1.

    15. Uses its own SMTP engine to send itself to the email addresses that it finds. The email has the following characteristics:

      From: [SPOOFED]

      Subject: [BLANK]

      Message:
      BRONTOK.A  [ By: H[REMOVED]M Community ]
      -- Hentikan kebobrokan di negeri ini --
      1. Adili Koruptor, Penyelundup, Tukang Suap, Penjudi, & Bandar NARKOBA
      ( Send to "NUSAKAMBANGAN")
      2. Stop Free Sex, Absorsi, & Prostitusi
      3. Stop (pencemaran laut & sungai), pembakaran hutan & perburuan liar.
      4. SAY NO TO DRUGS !!!
      -- KIAMAT SUDAH DEKAT --
      Terinspirasi oleh: Elang Brontok (Spizaetus Cirrhatus) yang hampir punah[ By: H[REMOVED]unity --


      Attachment:
      Kangen.exe

    recommendations

    Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

    • Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
    • If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
    • 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.
    • Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
    • Isolate infected computers quickly to prevent further compromising your organization. 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.

    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.
    4. Use the Security Response "Tool to reset shell\open\command registry subkeys."
    5. Delete any values added to the registry.
    6. Delete the scheduled task.
    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:
    Note:
    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 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.


    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, 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.


    4. Using the Security Response "Tool to reset shell\open\command registry subkeys."
    This risk makes changes to the Windows registry that may prevent you from running executable files. Security Response has developed a tool to reset these values to the default settings. This tool is the easiest way to fix this. Once you have run the tool, return to this page and continue with the removal.


    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:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    5. In the right pane, delete the value:

      "Bron-Spizaetus" = "%Windir%\INF\norBtok.exe"

    6. Navigate to the subkey:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

    7. In the right pane, delete the value:

      "Tok-Cirrhatus" = "%UserProfile%\Local Settings\Application Data\smss.exe"
    8. Navigate to the subkey:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    9. In the right pane, reset the value to its default value:

      "Shell" = "Explorer.exe"
    10. Navigate to the subkey:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    11. In the right pane, reset the following value to its default value if required:

      "NoFolderOptions" = "0" or "NoFolderOptions" = "1"
    12. Navigate to the subkey:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\explorer\advanced
    13. In the right pane, reset the following values to their default value if required:

      "Hidden" = "0"   or   "Hidden" = "1"
      "ShowSuperHidden" = "0"   or   "ShowSuperHidden" = "1"
      "HideFileExt" = "0"   or    "HideFileExt" = "1"

    14. Exit the Registry Editor.

    6. To delete the scheduled tasks added by the worm
      Click Start, and then click Control Panel. (In Windows XP, switch to Classic View.)
      In the Control Panel window, double click Scheduled Tasks.
      Right click the task icon and select Properties from pop-up menu.
      The properties of the task is displayed.
      Delete the task if the contents of the Run text box in the task pane, matches the following:

      %Windir\Tasks\At1.job


    Write-up by: Candid Wueest