Software Grand Exposure: SGX Cache Attacks Are Practical

TL;DR

This paper demonstrates that cache-based side-channel attacks on SGX enclaves are practical and can extract sensitive information like RSA keys and genome data, highlighting a significant security threat.

Contribution

The authors develop novel cache attack techniques that operate without interrupting enclave execution, proving the practicality and severity of cache side channels on SGX.

Findings

Successfully extracted RSA-2048 keys during decryption

Detected specific human genome sequences in genomic indexing

Attacks outperform previous cache side-channel methods

Abstract

Side-channel information leakage is a known limitation of SGX. Researchers have demonstrated that secret-dependent information can be extracted from enclave execution through page-fault access patterns. Consequently, various recent research efforts are actively seeking countermeasures to SGX side-channel attacks. It is widely assumed that SGX may be vulnerable to other side channels, such as cache access pattern monitoring, as well. However, prior to our work, the practicality and the extent of such information leakage was not studied. In this paper we demonstrate that cache-based attacks are indeed a serious threat to the confidentiality of SGX-protected programs. Our goal was to design an attack that is hard to mitigate using known defenses, and therefore we mount our attack without interrupting enclave execution. This approach has major technical challenges, since the existing cache monitoring techniques experience significant noise if the victim process is not interrupted. We designed and implemented novel attack techniques to reduce this noise by leveraging the capabilities of the privileged adversary. Our attacks are able to recover confidential information from SGX enclaves, which we illustrate in two example cases: extraction of an entire RSA-2048 key during RSA decryption, and detection of specific human genome sequences during genomic indexing. We show that our attacks are more effective than previous cache attacks and harder to mitigate than previous SGX side-channel attacks.