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Discovered: April 27, 2005
Updated: February 13, 2007 12:38:04 PM
Also Known As: Win32.Mytob.DG [Computer Assoc, Win32.Netsky.AH [Computer Asso, Email-Worm.Win32.Mydoom.am [Ka, W32/Netsky.b@MM [McAfee], W32/Mytob-CI [Sophos], W32/Netsky-B [Sophos], WORM_MYTOB.EK [Trend Micro], WORM_NETSKY.B [Trend Micro]
Type: Worm
Systems Affected: Windows

W32.Netsky.AI@mm is a mass-mailing worm that uses its own SMTP engine to send itself to email addresses it gathers from certain files on the compromised computer, and copies itself to mapped network drives. The worm also downloads a copy of Backdoor.Nemog.D .

Antivirus Protection Dates

  • Initial Rapid Release version April 28, 2005
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version April 28, 2005
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date May 04, 2005

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

Writeup By: Yana Liu

Discovered: April 27, 2005
Updated: February 13, 2007 12:38:04 PM
Also Known As: Win32.Mytob.DG [Computer Assoc, Win32.Netsky.AH [Computer Asso, Email-Worm.Win32.Mydoom.am [Ka, W32/Netsky.b@MM [McAfee], W32/Mytob-CI [Sophos], W32/Netsky-B [Sophos], WORM_MYTOB.EK [Trend Micro], WORM_NETSKY.B [Trend Micro]
Type: Worm
Systems Affected: Windows

When W32.Netsky.AI@mm is executed, it performs the following actions:

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

    • .msg
    • .oft
    • .sht
    • .dbx
    • .tbb
    • .adb
    • .doc
    • .wab
    • .asp
    • .uin
    • .rtf
    • .vbs
    • .html
    • .htm
    • .pl
    • .php
    • .txt
    • .eml

  2. Uses its own SMTP engine to send a copy of itself to the gathered email addresses. The email message typically has the following properties:

    From: Spoofed

    One of the following:

    • hello
    • hi
    • read it immediately
    • something for you
    • warning
    • information
    • stolen
    • fake
    • unknown

      One of the following:

    • anything ok?
    • what does it mean?
    • ok
    • i'm waiting
    • read the details.
    • here is the document.
    • read it immediately!
    • my hero
    • here
    • is that true?
    • is that your name?
    • is that your account?
    • i wait for a reply!
    • is that from you?
    • you are a bad writer
    • I have your password!
    • something about you!
    • kill the writer of this document!
    • i hope it is not true!
    • your name is wrong
    • i found this document about you
    • yes, really?
    • that is bad
    • here it is
    • see you
    • greetings
    • stuff about you?
    • something is going wrong!
    • information about you
    • about me
    • from the chatter
    • here, the serials
    • here, the introduction
    • here, the cheats
    • that's funny
    • do you?
    • reply
    • take it easy
    • why?
    • thats wrong
    • misc
    • you earn money
    • you feel the same
    • you try to steal
    • you are bad
    • something is going wrong
    • something is fool

      One of the following file names:

    • document
    • msg
    • doc
    • talk
    • message
    • creditcard
    • details
    • attachment
    • me
    • stuff
    • posting
    • textfile
    • concert
    • information
    • note
    • bill
    • swimmingpool
    • product
    • topseller
    • ps
    • shower
    • aboutyou
    • nomoney
    • found
    • story
    • mails
    • website
    • friend
    • jokes
    • location
    • final
    • release
    • dinner
    • ranking
    • object
    • mail2
    • part2
    • disco
    • party
    • misc

      with one of the following extensions:

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

      If the attachment is a .zip file, the copy of the worm may have one of the following second extensions:

    • .txt
    • .rtf
    • .doc
    • .htm
    • .exe
    • .scr
    • .com
    • .pif

  3. Downloads and executes the file NGCbanren.jpg from the www.newgenerationcomics.net/banner domain. This file is a copy of Backdoor.Nemog.D.

  4. Creates the mutex "AdmSkynetJKIS003", so that only one instance of the threat runs on the compromised computer.

  5. Displays the following message:

    Title: Error
    Message: The file could not be opened!

  6. Copies itself as %Windir%\Services.exe

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

  7. Adds the value:

    "service" = "%Windir%\services.exe -serv"

    to the registry subkey:


    so that it runs every time Windows starts.

  8. Deletes the following registry entries associated with Mydoom and Mimail variants:


  9. Searches drives C through Z for folder names containing the strings "Share" or "Sharing". If the drive is writeable, the worm copies itself to the folder and all subfolders as the following:

    • doom2.doc.pif
    • sex sex sex sex.doc.exe
    • rfc compilation.doc.exe
    • dictionary.doc.exe
    • win longhorn.doc.exe
    • e.book.doc.exe
    • programming basics.doc.exe
    • how to hack.doc.exe
    • max payne 2.crack.exe
    • e-book.archive.doc.exe
    • virii.scr
    • nero.7.exe
    • eminem - lick my pussy.mp3.pif
    • cool screensaver.scr
    • serial.txt.exe
    • office_crack.exe
    • hardcore porn.jpg.exe
    • angels.pif
    • porno.scr
    • matrix.scr
    • photoshop 9 crack.exe
    • strippoker.exe
    • dolly_buster.jpg.pif
    • winxp_crack.exe

  10. Creates the following zip archives in the Windows folder containing copies of the worm:

    • document.zip
    • msg.zip
    • doc.zip
    • talk.zip
    • message.zip
    • creditcard.zip
    • details.zip
    • attachment.zip
    • me.zip
    • stuff.zip
    • posting.zip
    • textfile.zip
    • concert.zip
    • information.zip
    • note.zip
    • bill.zip
    • swimmingpool.zip
    • product.zip
    • topseller.zip
    • ps.zip
    • shower.zip
    • aboutyou.zip
    • nomoney.zip
    • found.zip
    • story.zip
    • mails.zip
    • website.zip
    • friend.zip
    • jokes.zip
    • location.zip
    • final.zip
    • release.zip
    • dinner.zip
    • ranking.zip
    • object.zip
    • mail2.zip
    • part2.zip
    • disco.zip
    • party.zip
    • misc.zip


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: Yana Liu

Discovered: April 27, 2005
Updated: February 13, 2007 12:38:04 PM
Also Known As: Win32.Mytob.DG [Computer Assoc, Win32.Netsky.AH [Computer Asso, Email-Worm.Win32.Mydoom.am [Ka, W32/Netsky.b@MM [McAfee], W32/Mytob-CI [Sophos], W32/Netsky-B [Sophos], WORM_MYTOB.EK [Trend Micro], WORM_NETSKY.B [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. Run a full system scan and delete all the files detected as W32.Netsky.AI@mm.
  4. 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 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 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.Netsky.AI@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, 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.

4. 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 subkey:


  5. In the right pane, delete the value:

    "service" = "%Windir%\services.exe -serv"

  6. Exit the Registry Editor.

Writeup By: Yana Liu