TriHaRd: Higher Resilience for TEE Trusted Time

TL;DR

TriHaRd introduces a resilient trusted time protocol for TEEs that effectively counters clock manipulation attacks, ensuring reliable time measurement critical for secure applications.

Contribution

It presents TriHaRd, a novel TEE trusted time protocol with Byzantine resilience, improving upon prior methods by preventing malicious clock speed and offset manipulations.

Findings

TriHaRd mitigates known clock manipulation attacks.

It achieves high resilience through Byzantine-resilient updates.

Empirical results demonstrate improved security over Triad.

Abstract

Accurately measuring time passing is critical for many applications. However, in Trusted Execution Environments (TEEs) such as Intel SGX, the time source is outside the Trusted Computing Base: a malicious host can manipulate the TEE's notion of time, jumping in time or affecting perceived time speed. Previous work (Triad) proposes protocols for TEEs to maintain a trustworthy time source by building a cluster of TEEs that collaborate with each other and with a remote Time Authority to maintain a continuous notion of passing time. However, such approaches still allow an attacker to control the operating system and arbitrarily manipulate their own TEE's perceived clock speed. An attacker can even propagate faster passage of time to honest machines participating in Triad's trusted time protocol, causing them to skip to timestamps arbitrarily far in the future. We propose TriHaRd, a TEE trusted time protocol achieving high resilience against clock speed and offset manipulations, notably through Byzantine-resilient clock updates and consistency checks. We empirically show that TriHaRd mitigates known attacks against Triad.