SGX After Spectre and Meltdown: Status, Analysis and Remediations
Posted on January 25, 2018 by idfusionllc
Much has been written about the recently disclosed micro-architectural cache probing attacks named in the title of this document. These attacks, while known as a possibility for some time, have created significant concerns and remediation activity in the industry, secondary to the significant confidentiality threats they pose. These attacks are particularly problematic since they evade long standing protections that the industry has used as foundational constructs in the security design of modern operating systems.
While the threats to operating system protections have undergone significant discussion, there has been little official information surrounding the impact of this new threat class to Intel’s Software Guard eXtension (SGX) technology. This document is intended to provide support for system security architects and software engineers with respect to the impact of this new class of attack on SGX security guarantees. The development of this document was inspired by dialogue on the Intel SGX developer’s forum surrounding whether or not enclaves provide credible security guarantees in the face of these new threats.
Hardware and microcode enhancements introduced in the Intel Skylake micro-architecture provide the framework for the SGX Trusted Execution Environment (TEE). The SGX security architecture uses the notion of an enclave, which is an area of memory which contains data and code which can only be referenced by the enclave itself. Unauthorized access to these protected memory regions are blocked regardless of the privilege level of the context of execution attempting the access. As a result the premise is that enclaves will provide confidentiality and integrity guarantees even if the hardware, BIOS, hypervisor or operating system are compromised.[…]