Microarchitectural Cache Side-Channel Attacks

Bulletin ID:     AMD-SB-7025
Potential Impact: N/A
Severity: N/A

Summary

Researchers from Azure® Research, Microsoft® have provided to AMD a paper titled “Principled Microarchitectural Isolation on Cloud CPUs.” In their paper, the researchers describe a potential side-channel vulnerability on AMD CPUs. They propose that an attacker could leverage contention within the chipset coherence directory to observe activity across domains. This attack would not directly leak data and is similar to previous attacks involving cache side-channel vulnerabilities. The researchers present a proposal for a software-level mitigation strategy for protecting against microarchitectural side-channel attacks.

Mitigation

AMD believes that existing mitigation recommendations for prime and probe side-channel attacks remain applicable to the presented vulnerability. AMD recommends software developers employ existing best practices, including constant-time algorithms and avoid secret-dependent data accesses or control flows where appropriate to help mitigate this potential vulnerability.

Acknowledgement

AMD thanks Stavros Volos, Cédric Fournet, Jana Hofmann, Boris Köpf, and Oleksii Oleksenko of Azure Research, Microsoft for reporting this issue and engaging in coordinated vulnerability disclosure.

Revisions

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