Backdoor.Berbew.K

Printer Friendly Page

Discovered: October 08, 2004
Updated: February 13, 2007 12:28:13 PM
Type: Trojan Horse
Systems Affected: Windows


Backdoor.Berbew.K is a Backdoor Trojan horse that attempts to steal cached passwords.

Antivirus Protection Dates

  • Initial Rapid Release version October 09, 2004
  • Latest Rapid Release version August 20, 2008 revision 017
  • Initial Daily Certified version October 09, 2004
  • Latest Daily Certified version August 20, 2008 revision 016
  • Initial Weekly Certified release date October 12, 2004

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

Writeup By: Asuka Yamamoto

Discovered: October 08, 2004
Updated: February 13, 2007 12:28:13 PM
Type: Trojan Horse
Systems Affected: Windows


When Backdoor.Berbew.K runs, it performs the following actions:

  1. Creates a mutex named "KKQHOOK_20," which ensures that only one instance of the Trojan is running on the infected computer at one time.

  2. Drops the following files:
    %System%\[8 random characters].dll

    Note: %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  3. Creates the following files, which are used for saving password information and any downloaded configuration data for the Trojan:
    • %System%\dnkkq.dll
    • %System%\datkkq32.dll
    • %System%\kkq32.dll

  4. Creates several .htm files in the %Temp% directory.
    These file names follow the format [8 random characters].htm.

  5. Creates several .html files in the %Temp% directory.
    These file names follow the format [8 random characters].html. The Trojan may then open these files in Internet Explorer.

    Note: %Temp% is a variable that refers to the Windows temporary folder. By default, this is C:\Windows\TEMP (Windows 95/98/Me/XP) or C:\WINNT\Temp (Windows NT/2000).

  6. Adds the value:

    "Web Event Logger" = "{79FEACFF-FFCE-815E-A900-316290B5B738}"

    to the following registry key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
    ShellServiceObjectDelayLoad

  7. Adds the value:

    "1601" = "0"

    to the following registry keys:

    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4

  8. Adds the value:

    "GlobalUserOffline" = "0"

    to the following registry key:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
    Internet Settings

  9. Adds the value:

    "(Default)" = "[8 random characters].dll"

    to the following registry key:

    HKEY_CLASSES_ROOT\CLSID\{79FEACFF-FFCE-815E-A900-316290B5B738}\
    InProcServer32

  10. Adds the value:

    "ThreadingModel" = "Apartment"

    to the following registry key:

    HKEY_CLASSES_ROOT\CLSID\{79FEACFF-FFCE-815E-A900-316290B5B738}\
    InProcServer32

  11. Collects passwords from the infected computer, intercepts data that is entered into forms in Internet Explorer, and then sends the information gathered to a remote attacker.

  12. Uploads configuration data through the Web to the domain tat-xxxxxxx.ru


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: October 08, 2004
Updated: February 13, 2007 12:28:13 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. Restart the computer in Safe mode or VGA mode.
  4. Run a full system scan and delete all the files detected as Backdoor.Berbew.K.
  5. Restore the Internet Security settings.
  6. Delete the value that was 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, 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. 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:
3. To restart the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.
  • For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
  • For Windows NT 4 users, restart the computer in VGA mode.

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 Backdoor.Berbew.K 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." After you have restarted the computer in Safe mode, run the scan again.

    After the files are deleted, you may leave the computer in Safe mode and proceed with section 4. When you have finished section 4, restart the computer in Normal mode.
5. To restore the Internet Security settings:
  1. Start Internet Explorer.
  2. On the Tools menu, click Internet Options.
  3. On the Security tab, set the desired level for every zone.
    The easiest way to do this is to click Default Level for each one.
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 keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. On the Windows taskbar, click Start > Run.
  2. Type the following:

    regedit


  3. Click OK.

  4. Navigate to the following key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
    ShellServiceObjectDelayLoad

  5. In the right pane, delete the following value:

    "Web Event Logger" = "{79FEACFF-FFCE-815E-A900-316290B5B738}"

  6. Navigate to the following key:

    HKEY_CLASSES_ROOT\CLSID\{79FEACFF-FFCE-815E-A900-316290B5B738}\
    InProcServer32

  7. In the right pane, delete the following value:

    "Default" = "[8 random characters.dll]"

  8. Navigate to the following key:

    HKEY_CLASSES_ROOT\CLSID\{79FEACFF-FFCE-815E-A900-316290B5B738}\
    InProcServer32

  9. In the right pane, delete the following value:

    "Threading Model" = "Apartment"

  10. Navigate to the following key:

    HKEY_CURRENT_USER\Software\Microsoft\Windows

  11. In the right pane, delete the following value:

    "KKQHOOK" = "0x14"

  12. Reset the following values to their correct settings:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\1601
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1\1601
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2\1601
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3\1601
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4\1601

  13. Exit the Registry Editor.


Writeup By: Asuka Yamamoto