According to Pavel Galynin:
>
>wrong statements I make here, we all had to learn at some point, you
>weren't born clutching POSIX spec, were you?
Some people have made that accusation ;-) Actually for my vintage it
would probably have to be some K & R papers on their new idea for an
operating system.
>> - typically on a unix machine (regardless of
>> the architecture) you cannot take control of _any_ of the hardware, to
>> do so would result in a access violation and the termination of your
>> process.
>NONE? No bugs, no tricks, nothin' ?
Well, I have to admit you got me there. There was an exploit for the
Sun sparc machines where you could do interesting things with a
register window overflow trap (about the only case I can think of).
These problems are very machine and os version specific - the thing
will not work without the right sort of circumstances. Very different
to the situation with a pc running dos where all you need to do is get
the program running to infect.
>You just need to get the virus to execute, that's all. You can use
>eploits and stuff like that the crackers use.
Agreed - if you manage to get the virus to execute with sufficient
privilege then you are hosed. Getting that privilege is not always
easy and what works on one machine may fail totally on another.
There have been cases where this sort of thing was tried - the morris
internet worm springs to mind. The worm attempted to exploit some
"well known" holes to gain access.
>
>Just a simple question: New computers seem to come with flash bios, is
>it possible for a user priviledged program to get to the hardware
>necessary to reprogram it?
I believe that you need to poke a magic i/o location to put the flash
into program mode (I would hope so) in which case you should not be
able to do this - access to the in* & out* instructions are restricted
to ring 0 in protected mode (from memory again). Besides, from the
boards I have seen you need to change a jumper to enable the program
mode which is kinda hard to exploit via software ;-)
>I've neither expertise, nor time to do so at this time. I have to learn
>how to use Unix before programming for it.
>
Ummm for the purposes of the exercise you can just treat the kernel as
a large protected mode program. Most of the stuff that sets up the
processor for the kernel is in one file, locore.s on the machines I
use.
--
Brett Lymn, Computer Systems Administrator, AWA Defence Industries
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"Upgrading your memory gives you MORE RAM!" - ad in MacWAREHOUSE catalogue.
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