How to Disable Adobe Flash Protected Mode in Mozilla Firefox

For past some time, attack sites were using exploits in the Adobe Flash plugin for Firefox to run an exploit on a users PC. This was because the Adobe Flash plugin was run with the same integrity level as Mozilla Firefox making all the critical resources available to it. But starting from the version 11.3, the Adobe Flash plugin is installed with a protected mode by default. This protected mode makes Flash run with lower integrity levels and thus prohibits the runtime to access sensitive resources. But if you are facing browsing problems due to this protected mode, then you can disable it easily. Here is how :

  1. Open an elevated command prompt in Windows. If you are running Windows XP, then you must be logged in as an administrator. Then just open a command prompt Window. If you are running Windows Vista or 7, then you can follow these instructions on how to open an elevated command prompt in Windows.
  2. In the elevated command prompt, type the following command. This command is different for both the 32-bit and 64-bit edition of Windows.
    Edition of Windows Command Line
    32-bit notepad.exe %windir%\System32\Macromed\Flash\mms.cfg
    64-bit notepad.exe %windir%\Syswow64\Macromed\Flash\mms.cfg

    After typing in the command line, just hit Enter key on your keyboard.

    Disable Adobe Flash Protected Mode in Mozilla Firefox

  3. At this point two things may happen. Either the file would open in Windows Notepad, or you would get a message that this file does not exist. If you get a message that the Windows cannot find this file and it does not exist, then you should click on the Yes button to create this file.

    Disable Adobe Flash Protected Mode in Mozilla Firefox

  4. At the bottom of the mms.cfg file append a line ProtectedMode=0 and save the file by pressing the hotkey Ctrl + S or by selecting File → Save from the menubar.

    Disable Adobe Flash Protected Mode in Mozilla Firefox

  5. That’s it. You have successfully disabled the protected mode of Adobe Flash plugin for Mozilla Firefox.

If at a later stage, you want to enable the protected mode feature of Adobe Flash plugin for Mozilla Firefox, then follow the same instructions – only this time remove the ProtectedMode=0 from the mms.cfg file. The changes would take effect immediately.