Re: Cisco IOS Shellcode Presentation

[Valdis.Kletnieks () vt edu]

On Fri, 29 Jul 2005 18:57:15 CDT, "J.A. Terranson" said:

> This has nothing to do with the choice of "a general purpose CPU", it is a
> result of a specific architecture within the CPU chosen.  There is a real
> difference here.

Actually, although I've flamed Jason quite a bit, he *is* right in that the use
of *any* general purpose processor implies these sorts of vulnerabilities. The
*exact* results depend on things like the ABI they chose to use.  However,
saying "If they had used a different stack layout or different procedure call
conventions, none of this would have happened" is disingenuous. If you have an
ABI on anything we'd consider a "general purpose CPU", you have these same
*classes* of vulnerabilities.  The only way you can get rid of them is either to
not use a CPU at all (the FPGA/ASIC solution), or go with some exotic
architecture like Intel's  iAXP432(*) or the IBM S/38, which are both "tagged"
architectures, but hardly qualify as "general purpose".

Given the other choices, I can hardly say Cisco is guilty of *negligence*.
(On the other hand, if they used the word 'Unbreakable' to describe their
product, false advertising may be an issue.. ;)

(*) OK, so the 432 wasn't *really* able to provide much more than a hardware
implementation of Pascal-style type checking - the hidden 'gotcha' is that
it's fiendishly difficult to do operating system level coding on any sort
of B&D processor, because you can't typecast easily - and things like IOS
are almost entirely operating system level stuff...  In addition, you get
the performance penalties of hardware type checking....)

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