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Discovered: July 28, 2004
Updated: February 13, 2007 12:25:50 PM
Also Known As: TrojanSpy.Win32.Qukart.gen [Ka, W32/Berbew.G [Frisk], BackDoor-AXJ.gen [McAfee], BKDR_BERBEW.I [Trend]
Type: Trojan Horse
Systems Affected: Windows

Backdoor.Berbew.I attempts to steal cached passwords.

Antivirus Protection Dates

  • Initial Rapid Release version July 28, 2004
  • Latest Rapid Release version August 23, 2019 revision 016
  • Initial Daily Certified version July 28, 2004
  • Latest Daily Certified version August 15, 2019 revision 002
  • Initial Weekly Certified release date July 28, 2004

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

Technical Description

When Backdoor.Berbew.I is executed, it performs the following actions:

  1. Creates a mutex, "QueenKarton_13", which ensures that only one instance of the Trojan runs at once.

  2. Creates the files:
    • %System%\<8 random characters>.exe
    • %System%\<8 random characters>.dll

      Note: %System% is a variable. The Trojan locates the System folder and creates the file in 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).

  3. Creates several <8 random characters>.htm files in the %Temp% folder.

  4. Opens the <8 random characters>.htm files in Internet Explorer. Some of the files may access a predetermined URL at the domain,

  5. Adds the values:

    "(Default)" = "<8 random characters>.dll"
    "ThreadingModel" = "Apartment"

    to the registry key:


  6. Adds the value:

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

    to the registry key:


  7. Adds the value:

    "QueenKarton" = "D"

    to the registry key:


  8. Modifies the value:

    "1601" = "0"

    in the 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

  9. Modifies the value:

    "GlobalUserOffline" = "0"

    in the registry key:

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

  10. Adds the value:

    "BrowseNewProcess" = "yes"

    to the registry key:


  11. Collects passwords from the infected computer and intercepts data entered into the forms in Internet Explorer.

  12. May create the following files in the %System% folder to save this password information and any downloaded configuration data:
    • dnkkq.dll
    • kkq32.vxd
    • kkq32.dll
    • Rtdx1<number>.dat

  13. The stolen information is passed to the attacker by sending HTTP query strings. Configuration data may also be uploaded through the Web to a predetermined URL. at the domain,


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.


Removal using the Backdoor.Berbew.I Removal Tool

Symantec Security Response has developed a removal tool for Backdoor.Berbew.I. Use this removal tool first, as it is the easiest way to remove this threat.

The tool can be found here:

Note: The tool resets the following registry key values to default values as described below. Please note that if the settings on the affected computer were different from those listed below, that you may need to set these manually to the desired value.

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\"1601"=0
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1\"1601"=0
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2\"1601"=0
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3\"1601"=0
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4\"1601"=1

The current version of the tool will have a digital signature timestamp equivalent to 10/07/2004 6:35AM.

Note: The date and time displayed will be adjusted to your time zone, if your computer is not set to the Pacific time zone.

Manual Removal:

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.I.
  5. Delete the values 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: 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 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. 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.I, write down the location and file name, and then click Delete.

5. To delete the values 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. Click Start > Run.
  2. Type regedit

    Then click OK.

  3. Navigate to the key:


  4. In the left pane, delete the subkeys:
    "(Default)" = "%System%/<8 random characters>.dll"
    "ThreadingModel" = "Apartment"

  1. Navigate to the key:


  2. In the right pane, delete the value:

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

  3. Navigate to the key:


  4. In the right pane, delete the value:

    "QueenKarton" = "D"

  5. Exit the Registry Editor.

  6. Restart the computer in Normal mode.

Writeup By: Kevin Ha