Preventing Bios Flash Reflashing Permanently

Discussion in 'Computer Information' started by Bradly_Jeff, Feb 6, 2007.

  1. Bradly_Jeff

    Bradly_Jeff Guest

    Hi All,

    I'm looking for a way to permanently disable reflashing of the bios.
    I have several platforms, not a specific vendor or series.

    I thought of removing the leg incharge of writing to the flash, but
    it's not possible, since in some flashes, it's used for other commands
    besides write/erase commands.

    I heard there is a way to disable reflashing through the motherboard,
    but didn't find info about it.

    Any suggestions how to permanently disable reflashing?

    Bradly_Jeff, Feb 6, 2007
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  2. Bradly_Jeff

    Wes Newell Guest

    Replace the bios flash rom chip with a compatable rom, prom, eprom, etc.

    It's been a long time since I looked at the specs on these, but all have
    a control lead that could prevent this by being pulled high or low. That's
    not to say someone couldn't pull the chip, reprogram it and put it back in
    though. for that matter unless you seal it in some way, someone could
    always do this no matter what you did to try and stop them from flashing
    the original. So short of sealing a non flashable chip in place all you
    are going to do is make it harder for someone that knows what they are
    doing to do it. If you are looking for something less drastic, buy MB's
    with jumpers fro bios protection. Some, but not all boards have this
    feature. Basically pulling a pin on the chip high or low as I mentioned
    Wes Newell, Feb 6, 2007
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  3. Bradly_Jeff

    gowanoh Guest

    If there is no floppy disk or CD reader on the computer there is no way to
    flash the BIOS.
    gowanoh, Feb 6, 2007
  4. Bradly_Jeff

    Mike Walsh Guest

    Most BIOSs can be flashed from DOS. There are still many PCs with DOS e.g. all the ones with Win9x.
    Mike Walsh, Feb 6, 2007
  5. Sure there is:

    1) Use a program that runs under the host operating system to
    reprogram the flash. Such a program is not difficult
    to develop, just custom to the flash part and mb chipset.

    2) Put a DOS parition on the hard drive and load the flash
    utility and image into that partition and reboot to DOS.

    3) Plug a usb floppy/cdrom into the system and boot from it.

    Scott Lurndal, Feb 6, 2007
  6. Bradly_Jeff

    Paul Guest

    Find a blank BIOS chip that is OTP (one time programmable).
    These are used for devices where the manufacturer doesn't plan
    on doing field upgrades. If soldered in place, so much the better.
    (No temptation to swap out the BIOS chip, with an erasable

    Now, what is the problem with this concept ? The flash chip is
    not immutable. The DMI and ESCD areas of the BIOS chip, are
    updated every time new hardware is added or removed from the
    computer. On some BIOS designs, there are also a couple 2KB
    microcode caches, for the microcode patch to the processor.
    So the BIOS can write to certain areas of the chip, by itself.

    If a machine has a stable configuration, I suppose you can
    make a copy of the current contents of the flash, and put them
    in an OTP. But I bet before long, the user will be complaining
    about some error message that pops up during POST. So using
    an OTP might not be the perfect solution. Some testing required...

    Paul, Feb 7, 2007
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