Speculative execution side-channel vulnerabilities in micro-architecture processors have raised concerns about the security of Intel SGX. To understand clearly the security impact of this vulnerability against SGX, this paper makes the following studies: First, to demonstrate the feasibility of the attacks, we present SgxPectre Attacks (the SGX-variants of Spectre attacks) that exploit speculative execution side-channel vulnerabilities to subvert the confidentiality of SGX enclaves. We show that when the branch prediction of the enclave code can be influenced by programs outside the enclave, the control flow of the enclave program can be temporarily altered to execute instructions that lead to observable cache-state changes. An adversary observing such changes can learn secrets inside the enclave memory or its internal registers, thus completely defeating the confidentiality guarantee offered by SGX. Second, to determine whether real-world enclave programs are impacted by the attacks, we develop techniques to automate the search of vulnerable code patterns in enclave binaries using symbolic execution. Our study suggests that nearly any enclave program could be vulnerable to SgxPectre Attacks since vulnerable code patterns are available in most SGX runtimes (e.g., Intel SGX SDK, Rust-SGX, and Graphene-SGX). Third, we apply SgxPectre Attacks to steal seal keys and attestation keys from Intel signed quoting enclaves. The seal key can be used to decrypt sealed storage outside the enclaves and forge valid sealed data; the attestation key can be used to forge attestation signatures. For these reasons, SgxPectre Attacks practically defeat SGX's security protection. Finally, we evaluate Intel's existing countermeasures against SgxPectre Attacks and discusses the security implications.
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Time and Order: Towards Automatically Identifying Side-Channel Vulnerabilities in Enclave Binaries
While Intel SGX provides confidentiality and integrity guarantees to programs running inside enclaves, side channels
remain a primary concern of SGX security. Previous works
have broadly considered the side-channel attacks against SGX
enclaves at the levels of pages, caches, and branches, using a
variety of attack vectors and techniques. Most of these studies have only exploited the “order” attribute of the memory
access patterns (e.g., sequences of page accesses) as side
channels. However, the other attribute of memory access patterns, “time”, which characterizes the interval between two
specific memory accesses, is mostly unexplored. In this paper,
we present ANABLEPS, a tool to automate the detection of
side-channel vulnerabilities in enclave binaries, considering
both order and time. ANABLEPS leverages concolic execution
and fuzzing techniques to generate input sets for an arbitrary
enclave program, constructing extended dynamic control-flow
graph representation of execution traces using Intel PT, and
automatically analyzing and identifying side-channel vulnerabilities using graph analysis.
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- NSF-PAR ID:
- 10134886
- Date Published:
- Journal Name:
- International Symposium on Research in Attacks, Intrusions and Defenses
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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