W32.Hostidel.Trojan.B

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Discovered: November 17, 2003
Updated: February 13, 2007 12:13:59 PM
Type: Trojan Horse
Systems Affected: Windows


W32.Hostidel.Trojan.B is a variant of W32.Hostidel.Trojan that overwrites the Windows Hosts files. The Trojan also changes the Internet Explorer home page and search page and drops Backdoor.Daemonize in the %System% folder.

Antivirus Protection Dates

  • Initial Rapid Release version November 18, 2003
  • Latest Rapid Release version July 28, 2013 revision 019
  • Initial Daily Certified version November 18, 2003
  • Latest Daily Certified version July 28, 2013 revision 020
  • Initial Weekly Certified release date November 19, 2003

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

Writeup By: Kevin Ha

Discovered: November 17, 2003
Updated: February 13, 2007 12:13:59 PM
Type: Trojan Horse
Systems Affected: Windows


When W32.Hostidel.Trojan is executed, it performs the following actions:

  1. Creates the following files:
    • %Windir%\svchost.exe
    • %System%\svchostc.exe
    • %System%\svchosts.exe


      Notes:
    • %Windir% is a variable. The Trojan locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.
    • %System% is a variable. The Trojan locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  2. Creates the file:

    %Windir%\sysini.ini

    which contains the following text:

    ***Computer was successfully infected***

  3. Creates the following URL entries:
    • %Favorites%\escort.url
    • %Favorites%\hardcore porn.url
    • %Favorites%\adult%20dvd.url
    • %Favorites%\adult personals.url
    • %Favorites%\online dating.url
    • %Favorites%\Lesbian sex.url
    • %Favorites%\XXX Chat.url
    • %Favorites%\ADULT MOVIES.url
    • %Favorites%\Penis Enlargement Pill.url
    • %Favorites%\XXX MPEG.url
    • %Favorites%\Erotic Toons.url
    • %Favorites%\BLOWJOBS.url
    • %Favorites%\Hardcore Videos.url
    • %Favorites%\FREE SEX.url
    • %Favorites%\AMATEUR.url
    • %Favorites%\ASIAN.url
    • %Favorites%\ANAL SEX.url
    • %Favorites%\LIVE SEX.url
    • %Favorites%\Teen sex.url
    • %Favorites%\Schoolgirls.url
    • %Favorites%\Free Hardcore.url
    • %Favorites%\ANIME.url
    • %Favorites%\College Girls.url
    • %Favorites%\Chicks with dicks.url
    • %Favorites%\SHEMALES.url
    • %Favorites%\porn dvd.url
    • %Favorites%\porn video.url
    • %Favorites%\hugecock.url
    • %Favorites%\ORAL.url
    • %Favorites%\WEB CAMS.url
    • %Favorites%\transexuals.url
    • %Favorites%\Big boobs.url
    • %Favorites%\small tits.url
    • %Favorites%\Mature Gallery.url
    • %Favorites%\hairy.url
    • %Favorites%\Fioricet.url
    • %Favorites%\Tramadol.url
    • %Favorites%\Debt Consolidation.url
    • %Favorites%\Phentermine.url
    • %Favorites%\Online Casinos.url
    • %Favorites%\Online Casino.url
    • %Favorites%\Refinance Mortgage.url
    • %Favorites%\Adipex.url
    • %Favorites%\Ultram.url
    • %Favorites%\Soma.url
    • %Favorites%\Credit Card Debt.url
    • %Favorites%\Home Equity Loan.url
    • %Favorites%\Home Equity Loans.url
    • %Favorites%\Consolidate Debt.url
    • %Favorites%\Cash Advance.url
    • %Favorites%\Adipex Online.url
    • %Favorites%\Order Phentermine.url
    • %Favorites%\Fioricet Online.url
    • %Favorites%\Refinance.url
    • %Favorites%\Casinos.url
    • %Favorites%\Casino.url
    • %Favorites%\Buy Phentermine.url
    • %Favorites%\Online Gambling.url
    • %Favorites%\Debt Management.url
    • %Favorites%\1st search system.url
    • %Favorites%\Microsoft Security System.url


      Note: %Favorites% is a variable. The Trojan locates the Favorites folder by querying: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\Favorites in the Windows registry.

  4. Creates the following links on the desktop:
    • Find what you want.url
    • Your porno collection.url

  5. Searches for the Windows host file in the following location:

    %System%\drivers\etc\hosts

  6. Deletes all the entries from the Hosts files it finds, and then writes the following entries to those files:
    • 127.0.0.1     localhost
    • 63.246.157.35 homepage #1st search system
    • 63.246.157.36 security.com #Microsoft Security System

  7. Adds the value:

    "Online Service"="%Windir%\svchost.exe..."

    to the registry key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    so that the Trojan runs when you start Windows.

  8. Adds the value:

    "IDwin"="002000112003000000490033"

    to the registry key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Mserv

  9. Adds the value:

    "Start Page"="http:/ /sex.free4porno.net/search2.html"

    to the registry key:

    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Internet Explorer\Main


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: Kevin Ha

Discovered: November 17, 2003
Updated: February 13, 2007 12:13:59 PM
Type: Trojan Horse
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.Hostidel.Trojan.B.
  4. Reset the Internet Explorer search defaults and manually delete the files added to the Favorites folder.
  5. Delete the values that were added to the registry.
  6. Reverse the changes made to the Hosts file.
For specific details on each of these steps, read the following instructions.

1. Disabling 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, 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. Updating 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 on U.S. business days (Monday through Friday). 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. Scanning for and deleting 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.Hostidel.Trojan.B, click Delete.

4. Resetting the Internet Explorer defaults, manually deleting the files added to the Favorites folder
  1. Start Internet Explorer.
  2. Click the Tools menu, and then click Internet Options.
  3. Click the Programs tab.
  4. Click Reset Web Settings, and then click Yes to confirm.
  5. Click OK.
  6. Click the Favorites menu, and then click Organize Favorites.
  7. Remove the entries listed in step 3 of the "Technical Details" section.


5. Deleting the values from the registry


WARNING: 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, and then click Run. (The Run dialog box appears.)
  2. Type regedit

    Then click OK. (The Registry Editor opens.)

  3. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

  4. In the right pane, delete the value:

    "Online Service"="%Windir%\svchost.exe..."

  5. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Mserv

  6. In the right pane, delete the value:

    "IDwin"="002000112003000000490033"

  7. Exit the Registry Editor.
    6. Reversing the changes made to the Hosts file
    The Hosts file is not found on all the computers, and if it does exist, the location can vary. For example, if the file exists in Windows 98, it will usually be in C:\Windows; and in Windows 2000, it is in the C:\WINNT\SYSTEM32\DRIVERS\ETC folder. Also, there may be multiple copies of this file in different locations.

    The most efficient way to locate the file is to search for it.

    Follow the instructions for your operating system:
    • Windows 95/98/Me/NT/2000
      1. Click Start, point to Find or Search, and then click Files or Folders.
      2. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
      3. In the "Named" or "Search for..." box, type:

        hosts

      4. Click Find Now or Search Now.
      5. For each one that you find, note its location. (This is displayed in the "In Folder" column.)
      6. If any of the files that are found have a path that includes:

        \drivers\etc\hosts

        right-click the file, and then click "Open With."

      7. Deselect the "Always use this program to open this program" check box.
      8. Scroll through the list of programs and double-click Notepad.
      9. When the file opens, within the file, delete all the entries in the Hosts file, except for the following line:

        127.0.0.1     localhost

      10. Close Notepad and save your changes when prompted.

    • Windows XP
      1. Click Start, and then click Search.
      2. Click All files and folders.
      3. In the "All or part of the file name" box, type:

        hosts

      4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
      5. Click "More advanced options."
      6. Check "Search system folders."
      7. Check "Search subfolders."
      8. Click Search.
      9. Click Find Now or Search Now
      10. For each one that you find, note its location. (This is displayed in the "In Folder" column.)
      11. If any of the files that are found have a path that includes:

        \drivers\etc\hosts

        right-click the file, and then click "Open With."

      12. Deselect the "Always use this program to open this program" check box.
      13. Scroll through the list of programs and double-click Notepad.
      14. When the file opens within the file, delete all the entries in the Hosts file except for the following line:

        127.0.0.1     localhost

      15. Close Notepad and save your changes when prompted.


    Writeup By: Kevin Ha