Mutable Attestation or Measurement Reporting Data

Opis

The register contents used for attestation or measurement reporting data to verify boot flow are modifiable by an adversary.

A System-on-Chip (SoC) implements secure boot or verified boot. During this boot flow, the SoC often measures the code that it authenticates. The measurement is usually done by calculating the one-way hash of the code binary and extending it to the previous hash. The hashing algorithm should be a Secure One-Way hash function. The final hash, i.e., the value obtained after the completion of the boot flow, serves as the measurement data used in reporting or in attestation. The calculated hash is often stored in registers that can later be read by the party of interest to determine tampering of the boot flow. A common weakness is that the contents in these registers are modifiable by an adversary, thus spoofing the measurement.

Skutki

• Confidentiality

  Read Memory; Read Application Data

Zapobieganie

• Architecture and Design

  Measurement data should be stored in registers that are read-only or otherwise have access controls that prevent modification by an untrusted agent.

Słabość nadrzędna

• CWE-284 Improper Access Control

Kiedy powstaje

• Architecture and Design — Such issues can be introduced during hardware architecture or design and can be identified later during Testing or System Configuration phases.
• Implementation — If the access-controls which protecting the reporting registers are misconfigured during implementation, this weakness can arise.

Dotyczy

Not Language-Specific, Not OS-Specific, Not Architecture-Specific, Not Technology-Specific

Uwagi

This entry is still in development and will continue to see updates and content improvements.

Źródła

1. PCIe Device Measurement Requirements — Intel Corporation, 2018
2. BIOS Chronomancy: Fixing the Core Root of Trust for Measurement — John Butterworth, Cory Kallenberg, Xeno Kovah, 2013