[Cryptography] How to find hidden/undocumented instructions

[Kevin W. Wall]

[Not x-posting to Cypherpunks list as I'm not subscribed to that.]

On Thu, Aug 3, 2017 at 1:49 AM, grarpamp <grarpamp at gmail.com> wrote:
> On Wed, Aug 2, 2017 at 9:17 AM, Henry Baker <hbaker1 at pipeline.com> wrote:
>> https://raw.githubusercontent.com/xoreaxeaxeax/sandsifter/master/references/domas_breaking_the_x86_isa_wp.pdf
>>
>> Breaking the x86 ISA
>> Christopher Domas  xoreaxeaxeax at gmail.com  July 27, 2017
>>
..snip..
>
> "Lastly, a so-called `halt and catch fire' instruction was
> discovered on an as-yet unnamed x86 processor. This
> instruction, executed in ring 3 from an unprivileged process,
> appears to lock the processor entirely. To rule out kernel bugs,
> the instruction was tested against three Linux kernels and two
> Windows kernels, yielding the same results. Kernel debugging
> with serial I/O and interrupt hooks appeared to corroborate the
> results. At the time of this paper's publishing, the vendor has
> not been provided sufficient time to respond to the issue."
>
> This is nice work. These sort of fuzzers and searchers need a
> distributed network version to cover more space deeper and faster.

Unfortunately, while it is indeed excellent work, I fear the
researchers commitment to full disclosure has now revealed
to Skynet Intel's secret plans to destroy our future AI
overlords using this undocumented, unprivileged "halt and
catch fire" instruction. Surely it was humanity's last hope.

Oh well, AI world domination...how bad can it be, right?

-kevin
-- 
Blog: http://off-the-wall-security.blogspot.com/    | Twitter: @KevinWWall
NSA: All your crypto bit are belong to us.