Bootloader Sandboxing OROM Firmware Memory Segmentation

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Solution Overview

Problem

Computing devices are vulnerable to compromise during the boot sequence due to malicious OROM firmware, with existing solutions either banning OROM firmware execution, which restricts hardware use, or requiring user authorization, which burdens the user, and neither effectively prevents malicious access.

Innovation Solution

Implementing a sandbox to restrict the execution of OROM firmware by allocating specific memory address ranges and executing it in a restricted mode, thereby preventing unauthorized access and malicious actions without user intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If OROM firmware execution is banned, then device security is improved, but hardware functionality is restricted

Engineering Contradiction:
Improvedevice securityVSAvoidhardware functionality
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the execution environment by creating a sandbox with isolated memory address ranges for OROM firmware. The bootloader allocates specific memory regions that the firmware can access, while other memory regions remain protected. This segmentation allows the firmware to execute with limited access, maintaining security while enabling hardware functionality.

Inventive Principle:
Principle #1Segmentation

2Reliability

If user authorization is required for OROM firmware execution, then security is improved, but user experience deteriorates

Engineering Contradiction:
ImprovesecurityVSAvoiduser experience
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements automatic sandbox creation and memory allocation by the bootloader without requiring user intervention. The system self-manages the security constraints by programmatically allocating memory address ranges and enforcing access controls, eliminating the need for user authorization while maintaining security.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If OROM firmware is executed without restrictions, then hardware functionality is maintained, but device vulnerability increases

Engineering Contradiction:
Improvehardware functionalityVSAvoiddevice vulnerability
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by giving the OROM firmware specific memory access permissions tailored to its functional needs. The bootloader analyzes which memory regions the firmware requires and allocates only those specific ranges, rather than granting universal access. This localized permission approach enables hardware functionality while minimizing exposure to malicious actions.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3830729B1Boot firmware sandboxing
Publication Date: 2023.05.10 APPLE INC
  • EP3830729B1 patent drawingFigure 1
  • EP3830729B1 patent drawingFigure 2
  • EP3830729B1 patent drawingFigure 3A

AI summary

Techniques are disclosed relating to securely booting a computer system. In some embodiments, a bootloader initiates a boot sequence to load an operating system of the computing device and detects firmware of a peripheral device to be executed during the boot process to initialize the peripheral device for use by the computing device. In response to the detecting, the bootloader instantiates a sandbox that isolates the firmware from the bootloader. In various embodiments, the firmware is loaded from an option read-only memory (OROM) included the peripheral device and executed during the boot sequence to initialize the peripheral device. In some embodiments, the bootloader assigns one or more memory address ranges to the firmware, and the sandbox restricts the firmware from accessing memory addresses that are not included in the assigned one or more address ranges.