W32.Siltund.Worm

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Discovered: August 01, 2002
Updated: February 13, 2007 11:51:06 AM
Type: Worm
Systems Affected: Windows


W32.Siltund.Worm is a mass-mailing worm. It searches for email addresses in .htm* files that are in the current users personal folder, and sends itself to all addresses that it finds. The email message has the following characteristics:

From: "BIGBROTHER TVN POLSKA" <bigbrother@bigbrother.tvn.com.pl>
Subject:  BIGBROTHER SHOW !
Attachment: BigBrother_Live_Camera.exe

Antivirus Protection Dates

  • Initial Rapid Release version August 02, 2002
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version August 02, 2002
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date August 07, 2002

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

Writeup By: Yana Liu

Discovered: August 01, 2002
Updated: February 13, 2007 11:51:06 AM
Type: Worm
Systems Affected: Windows


When W32.Siltund.Worm runs, it does the following:

It copies itself as:

  • C:\%windir%\Temp\000000s.b64
  • C:\%system%\b1g_brother.exe

The attributes of these two files are set to hidden and read-only.

NOTES :
  • %windir% is a variable. The worm locates the \Windows folder (by default this is C:\Windows or C:\Winnt) and copies itself to the Temp subfolder under that location.
  • %system% is a variable. The worm locates the \Windows\System folder (by default this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.

To cause the worm to run when you start Windows, the worm inserts the following line into the Windows section of the C:\Windows\Win.ini file:

run=C:\%System%\b1g_brother.exe

The worm creates the C:\%windir%\Temp\00000b.rat file. The file is in email format and contains the worm as its attachment.

The worm obtains the SMTP server's information from the registry key

HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Account Manager\Accounts\00000001

It obtains the personal folder name of the current user from the registry key

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders

The worm then searches for email addresses in all .htm* files that are under this personal folder. The worm uses its own SMTP engine to send itself to all email addresses that it finds. The email message has the following characteristics:

From:  "BIGBROTHER TVN POLSKA" <bigbrother@bigbrother.tvn.com.pl>
Subject:  BIGBROTHER SHOW !
Attachment: BigBrother_Live_Camera.exe
Message:
Teraz mozesz ogladac BIGBROTHER SHOW za pomoca komputera! Jak to
zrobic? Wystarczy ze uruchomisz specjalny program
(BIGBROTHER_LIVE_CAMERA.EXE) , ktory zostal dolaczony do wiadomosci.
Ponadto za pomoca tego narzedzia mozesz nominowac wybrane przez ciebie
osoby, do opuszczenia domu Wielkiego Brata. Co miesiac rozlosowane beda
nagrody (telewizory, wieze stereo,
komputery ...i wiele ,wiele innych). Prosimy przysylac
opinie i komentarze na temat programu.
Zyczymy milej zabawy:
Redakcja programu.

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: Yana Liu

Discovered: August 01, 2002
Updated: February 13, 2007 11:51:06 AM
Type: Worm
Systems Affected: Windows


NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Restart the computer, update the virus definitions, run a full system scan, and delete all files that are detected as W32.Siltund.Worm.
  2. Remove the text that the worm added to the Win.ini file.

For details on how to do this, read the following instructions.

To delete files that are detected as W32.Siltund.Worm:
  1. Obtain the most recent virus definitions. There are two ways to do this:
    • Run LiveUpdate. LiveUpdate is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
    • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

      Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.
  2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
  3. Run a full system scan.
  4. Delete all files that are detected as W32.Siltund.Worm.

To remove the text that the worm added to the Win.ini file (Windows 95/98/Me only) :

NOTE: (For Windows Me users only) Due to the file-protection process in Windows Me, a backup copy of the file that you are about to edit exists in the C:\Windows\Recent folder. Symantec recommends that you delete this file before you continue with the steps in this section. To do this using Windows Explorer, go to C:\Windows\Recent, and in the right pane select the Win.ini file and delete it. It will be regenerated as a copy of the file that you are about to edit when you save your changes to that file.
  1. Click Start, and click Run.
  2. Type the following, and then click OK.

    edit c:\windows\win.ini

    The MS-DOS Editor opens.

    NOTE: If Windows is installed in a different location, make the appropriate path substitution.
  3. In the [Windows] section of the file, look for an entry similar to the following:

    run=C:\%System%\b1g_brother.exe
  4. If it exists, select the entire line. Be sure that you do not select any other text, and then press Delete.
  5. Click File, and click Save.
  6. Click File, and click Exit.


Writeup By: Yana Liu