White Paper: Hidden Risks of UEFI Secure Boot—and How RelianceOne™ Offers a Stronger Security Foundation

July 16, 2026

10 min read (2,167 words)

UEFI Secure Boot introduces significant risk by validating component signatures in isolation while leaving critical configuration data unauthenticated. This fragmented approach creates a weakness, allowing adversaries to subvert the entire chain of trust or execute rollback attacks using older, vulnerable kernels that still carry valid signatures.

Mercury’s RelianceOne™ mitigates these flaws by employing multiple defensive techniques to include a TPM backed measured boot approach wherein TPM stored cryptographic keys are only released if the entire environment matches a verified state, a TPM monotonic counter to prevent downgrade attacks, and an optional lightweight Rust-based hypervisor to continuously monitor CPU security registers.

Read this white paper to learn about:

  • Vulnerabilities from isolating component validation and unauthenticated configuration data.
  • Using TPM PCRs to unlock keys only when the entire system matches a verified state.
  • Hardware-enforced monotonic counters that permanently block outdated, vulnerable software.
  • A lightweight Rust hypervisor that protects CPU registers and security features in real-time.
  • Utilizing DRTM to "reboot trust" and isolate the system from early boot compromises.
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