Implementation · WhatsApp Private Processing
Published SEV-SNP attacks have not been tested against this deployment
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Evidence scope
An applicability question for Private Processing on AMD SEV-SNP. Battering RAM needed physical access to DDR4 servers. Interposers on SEV-SNP servers with DDR5 memory recovered a signing key from inside a guest with Ciphertext Hiding enabled, and broke memory integrity. The TEE.fail authors list EPYC processors based on Zen 4 and Zen 5 as affected, and neither team reports an SEV-SNP attestation forgery 6 7. RMPocalypse and Fabricked needed privileged host software on platforms without AMD's fixes. None of them was demonstrated against this deployment 5 8 9.
Meta reports that Private Processing runs on AMD SEV-SNP. Its threat model includes physical attacks on hosts, with data-centre security, memory encryption and third-party relays as mitigations 1. Trail of Bits notes that SEV-SNP does not fully protect against advanced physical attacks, and that Meta added controls on which CPUs are trusted 3. The TEE findings record SEV-SNP attestation defeated with a DDR4 memory-bus interposer 5, and forged from malicious host software on platforms without AMD's firmware fixes 8 9 10 11. Whether this deployment's protections resist those attacks remains an open question.
Sources: [1] · [3] · [5] · [6] · [7] · [8] · [9] · [10] · [11]