[Cryptography] You can't trust any of your hardware

[Alfie John]

On Fri, Aug 1, 2014, at 01:11 PM, Joe St Sauver wrote:
> The best practical solution I can think of to fix this would be to
> interpose a manually operated physical switch on each device that
> would need to be intentionally closed by the user to update the
> firmware on the device.
>
> [This sort of scheme would effectively be the firmware equivalent of a
> "write protect tab" on old floppy disks (man, sometimes I feel really
> old even *mentioning* stuff like that :-))]
>
> After completing the intentional firmware update the physical switch
> would then be reset to its normal open state, thereby preventing
> involuntary. programmatic updates of the device's firmware. That
> would, I think, *largely* eliminate the issue of firmware being
> tampered with by malware, while still allowing occaisionally needed
> updates to be intentionally applied (albeit only by someone physically
> in contact with the device).

A physical switch to make ROM writeable isn't new. One of the payloads
that the Chernobyl (aka CIH) virus did was cream your BIOS. Because of
this, later Pentium-II era motherboard needed jumpers to be closed in
order to write to BIOS. This was then replaced with the dual-BIOS
motherboards that you see today.

Alfie

-- 
  Alfie John
  alfiej at fastmail.fm