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  3. Infostealer.Banker.C

Infostealer.Banker.C - Removal

Risk Level 1: Very Low

Discovered:
April 2, 2007
Updated:
August 16, 2012 11:38:29 AM
Also Known As:
Troj/Bancos-BBT [Sophos], Troj/Bancos-BCV [Sophos], Trojan-Downloader.Win32.Agent.bvz [Kaspersky], Win32/Kollah.KX [Computer Associates], TROJ_ZBOT.AJC [Trend], TROJ_ZBOT.US [Trend]
Type:
Trojan
Infection Length:
34,304 bytes
Systems Affected:
Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP
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. Restart the computer using the Windows Recovery Console.
  3. Remove all the entries that the risk added to the hosts file.
  4. Update the virus definitions.
  5. Run a full system scan.
  6. 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 Folde (Article ID: Q263455).

2. To restart the computer using the Windows Recovery Console
To remove this threat it is necessary to restart the computer and run the Windows Recovery Console. For full details on how to do this please read the Microsoft Knowledge Base article, How to install and use the Recovery Console in Windows XP.

  1. Insert the Windows XP CD-ROM into the CD-ROM drive.
  2. Restart the computer from the CD-ROM drive.
  3. Press R to start the Recovery Console when the "Welcome to Setup" screen appears.
  4. Select the installation that you want to access from the Recovery Console.
  5. Enter the administrator password and press Enter.
  6. Type cd System
  7. Press Enter
  8. Type del ntos.exe
  9. Press Enter
  10. Type cd wsnpoem
  11. Press Enter
  12. Type del audio.dll
  13. Press Enter
  14. Type del video.dll
  15. Press Enter
  16. Type exit
  17. Press Enter. The computer will now restart automatically.
3. To remove all the entries that the risk added to the hosts file
  1. Navigate to the following location:

    • Windows 95/98/Me:
      %Windir%
    • Windows NT/2000/XP:
      %Windir%\System32\drivers\etc

      Notes:
    • The location of the hosts file may vary and some computers may not have this file. There may also be multiple copies of this file in different locations. If the file is not located in these folders, search your disk drives for the hosts file, and then complete the following steps for each instance found.
    • %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).

  2. Double-click the hosts file.
  3. If necessary, deselect the "Always use this program to open this program" check box.
  4. Scroll through the list of programs and double-click Notepad.
  5. When the file opens, delete all the entries added by the risk. (See the Technical Details section for a complete list of entries.)
  6. Close Notepad and save your changes when prompted.
4. 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.

    If you use Norton AntiVirus 2006, Symantec AntiVirus Corporate Edition 10.0, or newer products, LiveUpdate definitions are updated daily. These products include newer technology.

    If you use Norton AntiVirus 2005, Symantec AntiVirus Corporate Edition 9.0, or earlier products, LiveUpdate definitions are updated weekly. The exception is major outbreaks, when definitions are updated more often.


  • 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.

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.

5. To run a full system scan
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.

    For Norton AntiVirus consumer products: Read the document: How to configure Norton AntiVirus to scan all files.

    For Symantec AntiVirus Enterprise products: Read the document: How to verify that a Symantec Corporate antivirus product is set to scan all files.


  2. Run a full system scan.
  3. If any files are detected, follow the instructions displayed by your antivirus program.
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.

Note: Please restart the computer before editing registry.

6. 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 and delete the following registry entries:

    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"userinit" = "%System%\ntos.exe"
    • HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run\"userinit" = "%System%\ntos.exe"
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Network\"UID" = "[COMPUTERNAME]_[UNIQUE_ID]"
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\"{6780A29E-6A18-0C70-1DFF-1610DDE00108}" = "[HEXADECIMAL VALUE]"
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\"{F710FA10-2031-3106-8872-93A2B5C5C620}" = "[HEXADECIMAL VALUE]"


  5. Restore the following registry entries to its previous values:

    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Userinit" = "%System%\userinit.exe, %System%\ntos.exe"
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Userinit" = "%System%\userinit.exe, %System%\sdra64.exe"


  6. Exit the Registry Editor.
Writeup By: Elia Florio and Sean Kiernan

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