BIOS Platform State Verification Across Boot Sessions

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Solution Overview

Problem

Existing information handling systems lack trust chain linking between boot sessions, making them vulnerable to attacks and malicious activities, particularly during complex tasks like multi-step device configuration changes or firmware updates, which can exploit weak points in the boot flow.

Innovation Solution

An information handling system with a processor, cryptoprocessor, and BIOS firmware that securely records and verifies platform state records across boot sessions, ensuring only trusted updates are executed by comparing recorded and actual platform states during each boot session.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If trust chaining is implemented within a single boot session, then security verification of hardware configuration is improved, but trust chain linking between multiple boot sessions deteriorates (no trust chain spanning)

Engineering Contradiction:

Improvesecurity verificationVSAvoidtrust chain span

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent segments the trust chain verification into discrete boot session units, where each session independently verifies its own platform state through PCR measurements. The trust chain is segmented into per-session verification blocks rather than attempting continuous跨-session chaining, resolving the contradiction by making each segment self-contained and secure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by measuring and recording the platform state (PCR values) at the beginning of each boot session before any potentially malicious modifications can occur. This preliminary measurement establishes a baseline trust anchor that prevents adversaries from exploiting state changes between boots, as the initial state is captured and verified before any updates or modifications.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If multi-step firmware updates are allowed between boot sessions, then system update capability is improved, but vulnerability to attacks deteriorates (adversaries can exploit weak points in boot flow)

Engineering Contradiction:

Improveupdate capabilityVSAvoidattack vulnerability

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by pre-measuring and securing the platform state before firmware updates or configuration changes are applied. The PCR measurements capture the trusted state before any modifications, creating a preemptive security barrier that prevents adversaries from exploiting intermediate states during multi-step update processes.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent implements feedback by verifying the platform state at the beginning of each boot session against expected trusted configurations. This feedback mechanism allows the system to detect deviations or tampering that occur during or between update operations, enabling it to reject unauthorized firmware updates or configuration changes and maintain security integrity.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If state changes are permitted between boot sessions, then system configuration flexibility is improved, but security trust chaining deteriorates (malicious actors can emulate state changes)

Engineering Contradiction:

Improveconfiguration flexibilityVSAvoidtrust chain integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent captures the platform state through PCR measurements at the very beginning of each boot session, before any configuration changes or state transitions can occur. This preliminary capture creates an immutable reference point that maintains trust chain integrity even as the system later permits flexible state changes during operation, as each new boot session starts from a verified trusted state.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies periodic action by resetting and re-measuring the platform state at the start of each boot session. This periodic re-verification ensures that trust chain integrity is freshly established with each boot, preventing malicious accumulation of unauthorized state changes and allowing the system to periodically return to a known good state while maintaining configuration flexibility between boots.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11657158B2Systems and methods for extending boot security trust chaining to state changes between boot sessions

Publication Date: 2023.05.23 DELL PROD LP

AI summary

A method may comprise, on a basic input/output system (BIOS), executing a hardware attestation verification application configured to: (a) during a first boot session of the information handling system comprising the BIOS, execute a first stage of an update to the information handling system and securely record a platform state record associated with beginning of execution of a second stage of the update; and (b) during a second boot session of the information handling system: (i) obtain the platform state record; (ii) compare the platform state record to an actual platform state during boot process of the second boot session; and (iii) if the platform state record matches the actual platform state during boot process of the second boot session, permit execution of the second state of the update.