Verified UEFI Callback Chain for BIOS Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing information handling systems lack a mechanism to verify the integrity and order of event callbacks in the Unified Extensible Firmware Interface (UEFI) BIOS, making them vulnerable to tampering by malicious code that can alter or skip critical security authentication callbacks.
Innovation Solution
A processor in the information handling system monitors for UEFI events, reads a preauthorized event callback order, and compares it with the actual callback order, dispatching authorized functions from a preauthorized chain to detect and mitigate potential vulnerabilities, ensuring the integrity of the callback chain during boot operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system implements a verified callback chain mechanism to verify UEFI event callback orders, then security against tampering is improved, but device complexity increases due to additional monitoring and verification processes
Solution Approach 1:
The patent applies preliminary action by pre-authorizing the callback order during BIOS compilation and storing it in a read-only section of memory. This pre-established authorized callback order serves as a reference for later verification, allowing the system to detect tampering without adding complex real-time verification logic during runtime.
Solution Approach 2:
The patent implements feedback by continuously monitoring UEFI events and comparing actual callback execution orders against the preauthorized callback order. When a mismatch is detected, the system triggers security responses such as halting execution or alerting administrators, creating a closed-loop security verification mechanism.
2Measurement precision
If the system monitors and verifies each UEFI event callback order, then detection precision of vulnerabilities is improved, but loss of time occurs due to additional verification steps during boot operations
Solution Approach 1:
By pre-compiling and storing the authorized callback order in read-only memory during BIOS creation, the system eliminates the need for complex real-time analysis. The verification process simply compares current execution against the pre-established reference, maintaining high detection precision while minimizing time loss during boot operations.
3Reliability
If the system uses a preauthorized callback chain stored in read-only memory section, then integrity of BIOS is improved, but ease of manufacture decreases due to specialized memory requirements
Solution Approach 1:
The patent segments the BIOS structure by dividing it into a read-only section (storing the preauthorized callback order) and a writable section (for runtime operations). This segmentation allows the critical security reference data to be protected from modification while keeping the rest of the system flexible and manufacturable using standard memory components.
Data Source
AI summary
An information handling system includes a memory and a processor. The memory stores a basic input/output system (BIOS). The processor monitors the BIOS for a unified extensible firmware interface (UEFI) event. In response to a detection of the UEFI event, the processor reads a preauthorized event callback order. The processor compares a callback order for the UEFI event with the preauthorized event callback order. Based on the callback order for the UEFI event not matching the preauthorized event callback order, the processor detects a potential vulnerability in the UEFI event. In response to the detected potential vulnerability in the UEFI event, the processor dispatches one or more callback functions from the preauthorized event callback order.