An attacker would need to compromise our build pipeline to publish a backdoored VM image [1] and extract key material to forge an attestation from the hardware [2]. The build process publishes a hash of the code to Sigstore’s transparency log [3], which would make the attack auditable.

That said, a sufficiently resourced attacker wouldn’t need to inject a backdoor at all. If the attacker already possesses the keys (e.g. the attacker IS the hardware manufacturer, or they’ve coerced the manufacturer to hand the keys over), then they would just need to gain access to the host server (which we control) to get access to the hypervisor, then use their keys to read memory or launch a new enclave with a forged attestation. We're planning on writing a much more detailed blog post about "how to hack ourselves" in the future.

We actually plan to do an experiment at DEFCON, likely next year where we gives ssh access to a test machine running the enclave and have people try to exfiltrate data from inside the enclave while keeping the machine running.

[1] https://github.com/tinfoilsh/cvmimage

[2] https://arxiv.org/abs/2108.04575

[3] https://github.com/tinfoilsh/cvmimage/attestations