Re: My spin on the flash bios interface...

Alexander Kjeldaas (astor@guardian.no)
Fri, 13 Feb 1998 17:43:27 +0100

On Fri, Feb 13, 1998 at 04:00:02PM +1100, Kevin Lentin wrote:
> On Thu, Feb 12, 1998 at 07:53:12PM -0500, Dave Cinege wrote:
> > I would still consider cat>/dev/hda worse.
> > A BIOS chip is easily reprogrammed. Data that is gone, is gone.
>
> Disk data can be recovered from backup. A destroyed bios usually requires a
> trip to the manufacturer to get a new chip or a device to program the bios
> into the chip. You can boot a machine with a dead disk from floppy. You
> can't activate a machine with a screwed bios, can you?

Yes you can. You normally have a non-upgradeable part of the bios that
is able to load a new flash image from a floppy disk. AWARD has this
feature. (Check "Reprogramming a Boot Block BIOS" on
http://www.award.com/tech/).

This might not be fail-proof. AWARD's Boot Block BIOS seems to check
the flashable part by doing a checksum as this will catch most failed
upgrade attempts. However, if the attacker carefully makes a
replacement BIOS that has the correct checksum you can still be in
trouble.

astor

--
 Alexander Kjeldaas, Guardian Networks AS, Trondheim, Norway
 http://www.guardian.no/






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