CWE-1283: Mutable Attestation or Measurement Reporting Data

Description

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

Submission Date :

April 25, 2020, midnight

Modification Date :

2023-06-29 00:00:00+00:00

Organization :

Intel Corporation
Extended Description

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.

Example Vulnerable Codes

Example - 1

The SoC extends the hash and stores the results in registers. Without protection, an adversary can write their chosen hash values to these registers. Thus, the attacker controls the reported results.

To prevent the above scenario, the registers should have one or more of the following properties:Should be Read-Only with respect to an adversaryCannot be extended or modifiable either directly or indirectly (using a trusted agent as proxy) by an adversaryShould have appropriate access controls or protections

Related Weaknesses

This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined to give an overview of the different insight to similar items that may exist at higher and lower levels of abstraction.

CWE-284: Improper Access Control
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