Re: [PATCH v6 00/11] Intel SGX Driver

[Christian Stroetmann <stroetmann@ontolab.com>]

On the 03.Jan.2018 01:59, Dr. Greg Wettstein wrote:

Hello everybody
> On Dec 27,  9:46pm, Pavel Machek wrote:
> } Subject: Re: [PATCH v6 00/11] Intel SGX Driver
>
>> Hi!

[snip]

>> People usually assume that bitflip will lead "only" to
>> denial-of-service, but rowhammer work shows that even "random" bit
>> flips easily lead to priviledge escalation on javascript virtual
>> machines, and in similar way you can get root if you have user and
>> bit flips happen.
>>
>> So... I believe we should assume compromise is possible, not just
>> denial-of-service.
> Prudence always dictates that one assumes the worst.  In this case
> however, the bitflip attacks against SGX enclaves are very definitely
> in the denial-of-service category.  The attack is designed to trigger
> a hardware self-protection feature on the processor.
>
> Each page of memory which is initialized into an enclave has a
> metadata block associated with it which contains the integrity state
> of that page of memory.  The MM{E,U} hardware on an SGX capable
> platform checks this integrity data on each page fetch request arising
> from addresses/pages inside of an enclave.
>
> Forcing a bitflip in enclave memory causes the next page fetch
> containing the bitflipped location to fail its integrity check.  Since
> this technically shouldn't be possible, this situation was classified
> as a hardware failure which is handled by the processor locking its
> execution state, thus taking the machine down.
>
> It would seem to be a misfeature for the self-protection mechanism to
> not generate some type of trappable fault rather then generating a
> processor lockup but hindsight is always 20/20.  Philosophically this
> is a good example of security risk managment.  Locking a machine is
> obviously problematic in a cloud service environment, but it has to be
> taken in the perspective of whether or not it would be preferable to
> have a successful privilege escalation attack which could result in
> exfiltration of sensitive data.
>
> Philosophically we take the approach that for high security assurance
> environments it is virtually impossible to allow any untrusted code to
> run on a platform.  Which is why we focus on autonomous introspection
> for these environments.

Interesting.
I would like to hear more about this autonomous introspection concept, 
specifically
what it monitors and how it reacts on an issue.

Maybe you have a summary or short introduction of the concept or/and a 
link to a document.



Regards
Christian Stroetmann

>>> Unfortunately, in the security field it is way more fun, and
>>> seemingly advantageous from a reputational perspective, to break
>>> things then to build solutions.... :-)(
>> Well, yes :-). And I believe someone is going to have fun with SGX
>> ;-).
>> 									Pavel
> Arguably not as much fun as what appears to be pending, given what
> appears to be the difficulty of some Intel processors to deal with
> page faults induced by speculative memory references... :-)
>
> Best wishes for a productive New Year.
>
> Dr. Greg
>
> }-- End of excerpt from Pavel Machek
>
> As always,
> Dr. G.W. Wettstein, Ph.D.   Enjellic Systems Development, LLC.
> 4206 N. 19th Ave.           Specializing in information infra-structure
> Fargo, ND  58102            development.
> PH: 701-281-1686
> FAX: 701-281-3949           EMAIL: greg@enjellic.com
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