SoK: Security Below the OS -- A Security Analysis of UEFI
For cybersecurity researchers and practitioners, this work provides a structured understanding of UEFI attack surfaces and defenses, though it is a survey without novel empirical results.
This paper systematically analyzes UEFI security, including its supply chain, boot process, and vulnerabilities, and constructs a comprehensive threat model and MITRE ATT&CK-like taxonomy for UEFI attacks. It also reviews countermeasures to mitigate these threats.
The Unified Extensible Firmware Interface (UEFI) is a linchpin of modern computing systems, governing secure system initialization and booting. This paper is urgently needed because of the surge in UEFI-related attacks and vulnerabilities in recent years. Motivated by this urgent concern, we undertake an extensive exploration of the UEFI landscape, dissecting its distribution supply chain, booting process, and security features. We carefully study a spectrum of UEFI-targeted attacks and proofs of concept (PoCs) for exploiting UEFI-related vulnerabilities. Building upon these insights, we construct a comprehensive attack threat model encompassing threat actors, attack vectors, attack types, vulnerabilities, attack capabilities, and attacker objectives. Drawing inspiration from the MITRE ATT&CK framework, we present a MITRE ATT&CK-like taxonomy delineating tactics, techniques, and sub-techniques in the context of UEFI attacks. This taxonomy can provide a road map for identifying existing gaps and developing new techniques for rootkit prevention, detection, and removal. Finally, the paper discusses existing countermeasures against UEFI attacks including a variety of technical and operational measures that can be implemented to lower the risk of UEFI attacks to an acceptable level. This paper seeks to clarify the complexities of UEFI and equip the cybersecurity community with the necessary knowledge to strengthen the security of this critical component against a growing threat landscape.