Off-Host TEE Integrity Verification via OS Agent Measurements
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Solution Overview
Problem
Trusted Execution Environments (TEEs) within Information Handling Systems (IHSs) face challenges in ensuring integrity verification, as relying on potentially compromised components for self-validation is insufficient, and existing methods lack comprehensive off-host verification capabilities to detect tampering and maintain high performance.
Innovation Solution
Implementing a system and method for off-host integrity verification of TEEs, where an OS agent in an IHS obtains and transmits measurements from critical areas of Non-Volatile Memory to another IHS for comparison against reference hash values, ensuring integrity without relying on the TEE itself, and reporting results to OEMs or IT administrators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-validation methods are used within the TEE, then verification can be performed without external systems, but the integrity verification is insufficient because the TEE itself may be compromised
Solution Approach 1:
An external verification system acts as an intermediary between the TEE and the host system. This external system receives measurements from the TEE, compares them against known good values, and validates integrity independently of the TEE itself, thereby providing reliable verification even when the TEE might be compromised.
Solution Approach 2:
The verification function is segmented into separate components: the TEE generates measurements, the host system collects and transmits them, and the external verification system performs the actual validation. This segmentation allows each component to focus on its specific task and enables independent verification of the TEE.
2Reliability
If comprehensive integrity verification is implemented, then tampering detection capability is improved, but performance of the TEE may be degraded
Solution Approach 1:
Instead of verifying the entire TEE contents, the system performs partial verification by measuring only specific critical regions (such as code segments, data segments, or key structures). This selective measurement approach provides sufficient tampering detection capability while minimizing the performance overhead associated with comprehensive verification.
Solution Approach 2:
Baseline measurements of un-compromised TEE regions are established in advance during system setup or manufacturing. These pre-computed reference values are stored externally and used for rapid comparison during operation, enabling fast verification without requiring complex real-time analysis that would degrade TEE performance.
3Reliability
If measurements are transmitted to an external system for verification, then independent validation is achieved, but communication overhead and potential security risks are introduced
Solution Approach 1:
The system transmits copies of measurement data (such as hash values or checksums) to the external verification system rather than transmitting the actual TEE contents or sensitive information. This copying approach enables independent validation while minimizing security risks associated with data transmission, as the copied measurements are non-sensitive and cannot be used to reconstruct the original TEE state.
Data Source
AI summary
Systems and methods for off-host integrity verification of Trusted Execution Environments (TEEs) are described. In some embodiments, an Information Handling System (IHS) may include a processor and a memory coupled to the processor, the memory having program instructions stored thereon that, upon execution, cause the IHS to obtain, by an Operating System (OS) agent, a measurement of contents of a selected area of a Non-Volatile Memory (NVM) used by a TEE coupled to the processor, transmit the measurement from the OS agent to another IHS configured to perform integrity verification of the TEE based, at least in part, upon the measurement, and receive, at the OS agent from the other IHS, an indication of a result of the integrity verification.