3 ms·
Unfortunately, as usual, what Intel says and what actually happens are two quite different things: > Shortly after we learned about Intel’s Software Guard Exte
by mtgx 10y ago
Unfortunately, as usual, what Intel says and what actually happens are two quite different things:
> Shortly after we learned about Intel’s Software Guard
Extensions (SGX) initiative, we set out to study it in the
hope of finding a practical solution to its vulnerability
to cache timing attacks. After reading the official SGX
manuals, we were left with more questions than when we
started. The SGX patents filled some of the gaps in the
official documentation, but also revealed Intel’s enclave
licensing scheme, which has troubling implications.
> After learning about the SGX implementation and
inferring its design constraints, we discarded our draft
proposals for defending enclave software against cache
timing attacks. We concluded that it would be impossible
to claim to provide this kind of guarantee given the
design constraints and all the unknowns surrounding the
SGX implementation. Instead, we applied the knowledge
that we gained to design Sanctum [38], which is briefly
described in § 4.9.
> This paper describes our findings while studying SGX.
We hope that it will help fellow researchers understand
the breadth of issues that need to be considered before
accepting a trusted hardware design as secure. We also
hope that our work will prompt the research community
to expect more openness from the vendors who ask us to
trust their hardware.
https://eprint.iacr.org/2016/086.pdf https://eprint.iacr.org/2016/086.pdf
- dogma1138 10y agoThat's not that unusual for Intel or anyone else, while SGX doesn't protect against all types of attacks it does protect against some, I'm not seeing anything in SEV that can explicitly protect against cache timing attacks, and there is potential for the keys to leak through various side channel attacks in almost every implementation including SGX/SEV. Overall if you go through their paper page 38 has a good overview of various hardware security platforms / frameworks and what attacks they can protect against and what they are still vulnerable too. SGX seems to be vulnerable to 2 cache timing attacks and a page fault attack, it however does provide mitigation / protection against malicious hypervisor / OS attacks, as well as co residing malicious applications, and if you use SGX + TXT (& TPM) in theory you are only exposed to container level cache timing attacks which while might not be great is still something. Don't let perfect be the enemy of good :)
- ngneer 10y agoI do not know about "Unfortunately" and "as usual", but surely Intel cannot be held liable for researchers getting their hopes up about a system they have yet to examine. Defending against a software side-channel adversary was never a design objective of SGX, and Intel acknowledges so on slide 115 of the tutorial linked below. https://software.intel.com/sites/default/files/332680-002.pdf https://software.intel.com/sites/default/files/332680-002.pd...