W32.Mytob.BM@mm

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Discovered: April 24, 2005
Updated: February 13, 2007 12:37:50 PM
Also Known As: Win32.Mytob.BM [Computer Assoc, Net-Worm.Win32.Mytob.af [Kaspe, W32/Mytob.gen@MM [McAfee], W32/Mytob-AG [Sophos], WORM_MYTOB.CA [Trend Micro]
Type: Worm
Systems Affected: Windows


W32.Mytob.BM@mm is a mass-mailing worm with back door functionality that uses its own SMTP engine to send an email to addresses that it gathers from the compromised computer. The worm spreads through network shares protected by weak passwords.

Antivirus Protection Dates

  • Initial Rapid Release version April 25, 2005
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version April 25, 2005
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date April 27, 2005

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

Writeup By: Asuka Yamamoto

Discovered: April 24, 2005
Updated: February 13, 2007 12:37:50 PM
Also Known As: Win32.Mytob.BM [Computer Assoc, Net-Worm.Win32.Mytob.af [Kaspe, W32/Mytob.gen@MM [McAfee], W32/Mytob-AG [Sophos], WORM_MYTOB.CA [Trend Micro]
Type: Worm
Systems Affected: Windows


When W32.Mytob.BM is executed, it performs the following actions:

  1. Copies itself as %System%\w32NTupdt.exe.

    Notes: %System% is a variable that refers to the folder that Windows uses to store critical system files. By default, this is C:\Windows\System32 (Windows XP), C:\Winnt\System32 (Windows 2000, NT), or C:\Windows\System (Windows 9x, ME)

  2. Creates the following file:

    C:\hellmsn.exe

  3. Adds the value:

    "A New Windows Updater" = "w32NTupdt.exe"

    to the registry subkeys:

    HKEY_CURRENT_USER\Software\Microsoft\OLE
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\OLE
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
    RunServices
    HKEY_CURRENT_USER\SYSTEM\CurrentControlSet\Control\Lsa
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

    so that W32.Mytob.BM@mm runs every time Windows starts.

  4. Collects email addresses from the Windows Address Book and from the following locations:

    • %Windir%\Temporary Internet Files
    • %Userprofile%\Local Settings\Temporary Internet Files
    • %System%

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

  5. Harvests email addresses from files with the following extensions:

    • .adb*
    • .asp*
    • .dbx*
    • .htm*
    • .php*
    • .sht*
    • .tbb*
    • .txt
    • .wab*

  6. Avoids sending a copy of itself to email addresses containing any of the following strings:

    • .edu
    • .gov
    • .mil
    • acketst
    • arin.
    • avp
    • be_loyal:
    • berkeley
    • borlan
    • bsd
    • example
    • fido
    • foo.
    • fsf.
    • gnu
    • google
    • gov.
    • iana
    • ibm.com
    • icrosof
    • ietf
    • inpris
    • isc.o
    • isi.e
    • kernel
    • linux
    • math
    • mit.e
    • mozilla
    • mydomai
    • nodomai
    • panda
    • pgp
    • rfc-ed
    • ripe.
    • ruslis
    • secur
    • sendmail
    • sopho
    • syma
    • tanford.e
    • unix
    • usenet
    • utgers.ed

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

    From:
    One of the following: (Spoofed)

    • accoun
    • admin
    • anyone
    • bugs
    • certific
    • contact
    • feste
    • gold-certs
    • help
    • icrosoft
    • info
    • listserv
    • nobody
    • noone
    • not
    • nothing
    • ntivi
    • page
    • postmaster
    • privacy
    • rating
    • root
    • samples
    • service
    • site
    • soft
    • somebody
    • someone
    • submit
    • support
    • the.bat
    • webmaster
    • you
    • Your

      followed by one of the following domains:

    • aol.com
    • cia.gov
    • fbi.gov
    • hotmail.com
    • juno.com
    • msn.com
    • yahoo.com


      Subject:
      One of the following:

    • hello
    • Good Day
    • Error
    • Mail Delivery System
    • Mail Transaction Failed
    • Server Report
    • Status
    • [random characters]


      Message:
      One of the following:

    • Mail transaction failed. Partial message is available.
    • The message contains Unicode characters and has been sent as a binary
      attachment.
    • The message cannot be represented in 7-bit ASCII encoding and has been
      sent as a binary attachment.
    • The original message was included as an attachment.
    • Here are your banks documents


      Attachment:
      One of the following:

    • body
    • data
    • doc
    • document
    • file
    • message
    • readme
    • test
    • text
    • [random file name]


      with one of the following extensions:

    • .pif
    • .scr
    • .exe
    • .bat
    • .cmd
    • .zip

  8. May open an FTP server using a random port.

  9. Opens a back door by connecting to IRC channel #.a on domain no.siberkorsan.com or IRC channel #.s on domain av4.sytes.net and listens for commands. This allows the remote attacker to perform any of the following actions:

    • Download and execute files, which may be an updated version of the worm.
    • Remove or disable the worm

  10. Attempts to copy itself to network shares using user name and password of the currently logged-on user. If unsuccessful, the worm uses the following list of passwords to access the network shares:

    00000
    000000
    00000000
    0wn3d
    0wned
    111111
    11111111
    121212
    123123
    123321
    12345
    123456
    1234567
    12345678
    123456789
    12346
    123467
    1234678
    12346789
    123467890
    1234qwer
    123abc
    123asd
    123qwe
    54321
    654321
    abc123
    access
    ACCESS
    account
    accounting
    accounts
    Admin
    ADMIN
    admin123
    Administrador
    Administrateur
    Administrator
    ADMINISTRATOR
    administrator
    backup
    barbara
    blank
    bruce
    capitol
    changeme
    Cisco
    CISCO
    cisco
    compaq
    control
    database
    databasepass
    databasepassword
    db1234
    dbpass
    dbpassword
    default
    domain
    domainpass
    domainpassword
    exchange
    exchnge
    frank
    freddy
    Guest
    GUEST
    guest
    headoffice
    heaven
    homeuser
    internet
    intranet
    katie
    login
    loginpass
    nokia
    oeminstall
    oemuser
    office
    orange
    outlook
    pass123
    pass1234
    passphra
    passwd
    Password
    PASSWORD
    password
    password1
    password123
    qwerty
    server
    siemens
    spencer
    sqlpass
    staff
    student
    student1
    susan
    system
    teacher
    technical
    turnip
    Unknown
    unknown
    user1
    usermane
    username
    userpassword
    win2000
    win2k
    win98
    windose
    windows
    windows2k
    windows95
    windows98
    windowsME
    WindowsXP
    windowz
    windoze
    windoze2k
    windoze95
    windoze98
    windozeME
    windozexp
    winnt
    winpass
    winston
    winxp
    wired
    xxxxx
    xxxxxx
    xxxxxxx
    xxxxxxxx
    xxxxxxxxx
    yellow


Recommendations

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: Asuka Yamamoto

Discovered: April 24, 2005
Updated: February 13, 2007 12:37:50 PM
Also Known As: Win32.Mytob.BM [Computer Assoc, Net-Worm.Win32.Mytob.af [Kaspe, W32/Mytob.gen@MM [McAfee], W32/Mytob-AG [Sophos], WORM_MYTOB.CA [Trend Micro]
Type: Worm
Systems Affected: 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. Update the virus definitions.
  3. Do one of the following:
      • Windows 95/98/Me: Restart the computer in Safe mode.
      • Windows NT/2000/XP: End the malicious process.
  4. Run a full system scan and delete all the files detected as W32.Mytob.BM@mm.
  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:
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 the document: 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 document: 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 restart the computer in Safe mode or end the malicious process
      Note: Because this virus may utilize a large amount of System Resources, your Symantec Anti-Virus product may be difficult or slow to load or scan. To avoid this, please follow these instructions:

        Windows 95/98/Me
        Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode. For instructions, read the document: How to start the computer in Safe Mode.

        Windows NT/2000/XP
        To end the malicious process:
        1. Press Ctrl+Alt+Delete once.
        2. Click Task Manager.
        3. Click the Processes tab.
        4. Double-click the Image Name column header to alphabetically sort the processes.
        5. Scroll through the list and look for w32NTupdt.exe
        6. If you find the file, click it, and then click End Process.
        7. Exit the Task Manager.


    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.Mytob.BM@mm, click Delete.

      Note:
      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, restart the computer in Normal mode and proceed with section 4.

      Warning messages may be displayed when the computer is restarted, as the threat has not been fully removed at this point. Please ignore these messages and just 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.

    4. Navigate to the subkeys:

      HKEY_CURRENT_USER\Software\Microsoft\OLE
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\OLE
      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
      RunServices
      HKEY_CURRENT_USER\SYSTEM\CurrentControlSet\Control\Lsa
      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

    5. In the right pane, delete the value:

      "A New Windows Updater" = "w32NTupdt.exe"

    6. Exit the Registry Editor.


    Writeup By: Asuka Yamamoto