Firmware password -- stop booting in target disk mode?

Discussion in 'iMac' started by immobilus, Jan 25, 2017.

  1. immobilus macrumors member

    May 5, 2012
    I have an iMac I bought from Best Buy in 2011. I moved around the world and country over two years and left it with my mother. Prior to doing so, I set a firmware password.

    I've forgotten it.

    I've been able to access my account, login, upgrade MacOS, etc., it only requires the password if I attempt to boot with arguments, i.e. recovery mode.

    Best Buy only archives purchase invoices for three years. Apple won't assist with the unlock without an invoice. I've basically just settled with the fact that I can use my iMac, but can never use safe mode, target disk mode, etc.

    I made a mistake. When upgrading it to macOS Sierra, I thought I had a work around. I created an OS installer USB, used terminal to flag the computer in target disk mode (thinking if it didn't work, long shot, I could just turn off the computer and turn it back on--the OS would load as normal).

    It didn't work. Now it's stuck trying to boot in target disk mode, which requires the firmware password. Turning it off and on does not reset the target mode argument at boot. It keeps trying target disk mode, resulting in demands for my password.

    Is there an argument that can be made or something I can do to make the iMac boot normally, so it will stop asking me for my firmware password and allow me to login?
  2. Fishrrman macrumors G4


    Feb 20, 2009
    If I recall, there are ebay "sellers" who offer "firmware password fixes".

    These may not be "authorized by Apple", but they may work.

    Your story is the perfect example as to why one should NEVER NEVER use a firmware password unless one has a very good reason to require doing so.
  3. mikeboss macrumors 65816


    Aug 13, 2009
    change the amount of RAM and reset PRAM (option-command-P-R) during first boot and the password should be gone...
  4. chrfr macrumors 603

    Jul 11, 2009
    That no longer works for Macs made in 2010 or later.
  5. maflynn Moderator


    Staff Member

    May 3, 2009
    That would seem like a huge security vulnerability - why have a password when you can easily work around it.
  6. casperes1996 macrumors 65816


    Jan 26, 2014
    Horsens, Denmark
    Was a glitch - got fixed
  7. chrfr macrumors 603

    Jul 11, 2009
    Indeed, it effectively made firmware passwords useless, and it was this way for years.

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