CWE-1283: Mutable Attestation or Measurement Reporting Data

How it's found

Mutable Attestation or Measurement Reporting Data is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.

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.

Consequences

• Read Memory, Read Application Data

Mitigations

• 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.

Where this fits in a TurboPentest engagement

This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.

Frequently asked questions

Related CWEs

• Pillar weakness
  CWE-284: Improper Access Control