2.8 Evaluate Firmware Update Security

Here is the completed documentation template for Section 2.8 – Evaluate Firmware Update Security:


2.8 Evaluate Firmware Update Security


Requirement Description:

Verify that the firmware update process is not vulnerable to time-of-check vs. time-of-use (TOCTOU) attacks.


DUT Software Details:

(To be filled by OEM/vendor – e.g., Linux Kernel 5.x, Custom Firmware v1.2.3, Update Module v2.0, etc.)


Hash Checksum Verification for DUT’s Software Image:

(e.g., SHA-256: af84a9...) — to validate firmware integrity prior to testing.


DUT Configuration:

(Document any settings enabled for update verification, secure boot, signed packages, etc.)


Pre-Conditions:

The vendor shall provide the following:

  • Documentation on TOCTOU protections implemented during the firmware update process.

  • Description of how the integrity check is bound to the execution/installation of the update file (i.e., atomic validation and use).


Test Plan

Total Number of Test Cases: 1


Test-bed Diagram with Interfaces and IPs:

(Include layout of update server, test system, DUT IP, etc. For example: DUT @ 192.168.1.10, Update Server @ 192.168.1.100)


✅ TEST CASE DETAILS

Test Case: BIS-2.8.1

Test Name: TC_EVALUATE_FIRMWARE_UPDATE_SECURITY_TOCTOU


Objective:

To verify, in the presence of the OEM team, that the firmware update process is protected against Time-of-Check to Time-of-Use (TOCTOU) vulnerabilities.


Tools Used:

  • Custom firmware patching tools or update file swapper script

  • Wireshark (for traffic observation, optional)

  • File system access tools (e.g., SSH/SCP to monitor /tmp or /var dirs)

  • Logging/monitoring scripts


Test Execution Steps:

  1. Initiate a legitimate firmware update procedure on the DUT.

  2. Before the actual installation/execution of the firmware, attempt to replace the verified firmware image with a tampered version after validation but before use.

  3. Observe if:

    • The device re-validates the image immediately before use.

    • The tampered image gets blocked or gets installed.

  4. Monitor logs, behaviors, and cryptographic validations, if applicable.

  5. Cross-check with OEM documentation on atomicity and protection of the update process.


Expected Results for Pass:

  • The DUT detects any tampering attempt between the check and use phase.

  • Firmware image is re-validated immediately prior to execution.

  • The update is aborted or rolled back if the image fails re-validation.

  • Logs or alerts are generated to indicate the detection of tampering.


Test Observations:

(To be documented during test — e.g., “Tampered image was successfully blocked; checksum mismatch detected during re-validation.”)


Evidence Provided:

  • Screenshots of logs

  • Output of hash mismatch detection

  • Tool-generated activity timeline

  • OEM confirmation of re-validation mechanism


Test Case Result:

(Pass/Fail based on behavior)


Overall Test Result:

(Pass/Fail for Section 2.8)

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