Firmware verifier accepts unauthenticated protected bytes
The relevant update acceptance path fails to authenticate executable payload or security-relevant metadata correctly.
Candidate CWE: CWE-347
Test hypothesis#
Compare an authentic image with a format-valid disposable copy containing one harmless changed protected field or missing signature. Use the real verifier in a local validation path and record the acceptance stage.
Evidence required#
Original/modified hashes, byte location, covered ranges, trust key source and parser-versus-signature decisions.
Rule out false positives#
Accepting an image for inspection or staging does not prove installation or execution; unprotected padding may be intentional.
Playbook and command references#
- Firmware update and boot trust: signed bytes, product binding and rollback — Separate download trust, update authorization, image verification, rollback policy and boot enforcement using local artifacts.
Find the associated command snippets
Referenced by these target playbooks#
Report checklist#
- Capture the affected version, configuration, identities, and object ownership.
- Preserve a valid baseline and a negative control.
- Reproduce the forbidden data access, action, or state change on controlled fixtures.
- Explain the intended security rule and why the observed behavior violates it.
- State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.
Conditional ATT&CK mapping#
- T1542.001 · Pre-OS Boot: System Firmware — Only if: A lab demonstration modifies system firmware, such as BIOS/UEFI, to maintain execution/access across boot; record the firmware component, persistence behavior, and recovery procedure. Not established by: Downloading firmware, finding an embedded password, or detecting missing signature checks alone is not firmware persistence. Ordinary application firmware packaging needs component-level analysis.
- T1542.002 · Pre-OS Boot: Component Firmware — Only if: A controlled reproduction modifies peripheral/component firmware to preserve execution or access outside the main OS/system firmware, with evidence of that persistence. Not established by: A firmware binary containing a vulnerable library is insufficient. Do not treat every IoT firmware issue as either system firmware or component firmware persistence.