As just lately as December 2025, the SEI’s CERT Coordination Middle (CERT/CC) documented a UEFI-related vulnerability in sure motherboard fashions, illustrating that early-boot firmware conduct continues to current safety challenges regardless of requiring native bodily entry to use. UEFI is a crucial component of system firmware as a result of it initializes {hardware} and boots up the working system. Tampering with UEFI can help assaults which can be significantly tough to detect and mitigate.
This vulnerability is the newest situation reported, however it isn’t an outlier. CERT/CC reported seven UEFI vulnerability notes in 2025. Whereas small in comparison with reported vulnerabilities in different software program, the implications of a possible UEFI assault are sometimes extra severe given the extraordinarily excessive privileges UEFI firmware possesses. Equally essential, UEFI firmware is commonly giant, advanced, and opaque, which makes it difficult to investigate for safety issues.
On the SEI we have now made the invention and remediation of UEFI vulnerabilities a precedence. On this weblog submit, we discover UEFI and introduce CERT UEFI Parser, a brand new, open supply software that makes use of program evaluation to disclose the structure of UEFI software program, and discover this veiled supply of vulnerabilities. The brand new parser is the results of that multiyear effort and helps output in human-readable textual content, JSON, and SBOM-ready JSON, making it well-suited to firmware audits, investigations, asset inventories, and automatic workflows. upports output in human-readable textual content, JSON, and SBOM-ready JSON, making it well-suited to firmware audits, investigations, asset inventories, and automatic workflows.
Why Do We Want a UEFI Parser?
The Unified Extensible Firmware Interface (UEFI) specification, began by Intel in 2004, is a community-driven undertaking geared toward creating a standard bootloader for all trendy computing units. It replaces the normal Primary Enter/Output System (BIOS) that beforehand had the position of beginning the working system when the {hardware} is powered up.
UEFI is a specification, and its implementation varies by vendor. Every vendor brings completely different approaches, customized knowledge constructions, and their very own interpretations of specs. This fragmentation yields an ecosystem with little uniformity and even much less transparency as a result of most code is proprietary. Bootloaders maintain a delicate place in computing structure—they’re the primary layer of software program between the {hardware} and the working system. Nonetheless, the place there may be software program, there may be the chance for vulnerabilities and exploits.
CERT started creating the UEFI parser software in early 2020 as a part of our systemic vulnerability analysis initiative, the place we got down to perceive and shield a few of the most invisible and difficult-to-manage ecosystems in trendy computing. We use the time period “systemic vulnerability” to explain a deeply embedded flaw that’s pervasive throughout a number of methods, distributors, or implementations; tough to detect or remediate as a result of advanced dependencies and elusive root causes; and infrequently dismissed as inherent to the system itself. The UEFI ecosystem exemplifies this definition. Firmware is tough to examine, inconsistently documented, and difficult to handle throughout numerous {hardware} platforms, which makes vulnerabilities each tough to find and much more obscure when it comes to their broader influence.
Early analysis in UEFI vulnerabilities uncovered a labyrinth of knowledge codecs (each when it comes to binary artifacts and their metadata) in digital UEFI environments, every with their very own distinctive constructions and assumptions, together with many extra advanced customized codecs that dwell exterior conventional executable file codecs, similar to Microsoft’s Transportable Executable (PE) or the Executable and Linkable Format (ELF) generally utilized by Linux methods. These parts are sometimes undocumented, extremely vendor-specific, and outdoors the scope of current instruments (For extra on current instruments see right here and right here). We additionally encountered challenges in understanding how vulnerabilities propagated throughout completely different tasks. For instance, when a flaw was disclosed in a particular firmware construct, it was usually unclear how a lot of the underlying code was reused in different UEFI tasks. And not using a constant solution to rapidly parse and evaluate parts, figuring out the checklist of affected fashions for a vulnerability was extraordinarily tough. It was quickly apparent that we wanted to develop a software to scale our analysis; welcome, CERT UEFI Parser.
In reverse engineering, parsing and understanding binary file codecs is a vital exercise to get well the construction obligatory to investigate and perceive binary artifacts. Efficient parsing have to be environment friendly and correct, incrementally decoding firmware binaries into higher-level constructions that help exploration and evaluation. Constructed on utilizing such strong and extensible parsing frameworks, CERT UEFI Parser provides researchers, system directors, and safety lovers a robust and clear solution to examine and analyze firmware. Its options embrace the capabilities to:
- Decompose firmware photographs, expose hidden constructions, and help deeper reverse engineering and code-reuse evaluation throughout the various UEFI panorama
- parse firmware ROMs, UEFI firmware photographs, PE recordsdata, installer packages, and extra
- help output in human-readable textual content, JSON, and SBOM-ready JSON, making it well-suited to firmware audits, investigations, asset inventories, and automatic workflows
The software displays years of amassed analysis into how the firmware is constructed, the way it varies throughout distributors, and the way it may be analyzed extra systematically.
Case Research: Investigating the PKFail Vulnerability
Contemplate the PKFail vulnerability, revealed in August 2024. Within the PKFail vulnerability, Platform Keys (PKs) utilized in growth and testing have been mistakenly hardcoded into the manufacturing firmware for a number of distributors. These keys usually included the label “DO NOT TRUST.”
Let’s stroll by means of how somebody may examine a binary file to find out whether it is sufferer to PKFail. We’re utilizing the Lenovo Thinkserver 140 ROM. As a begin, let’s use the parsed file in JSON format in order that we will seek for strings, similar to “DO NOT TRUST,” an attribute generally encoded with hard-coded take a look at software program keys.
Determine 1: CERT UEFI Parser in JSON mode permits for looking out by string
This discovering is especially noteworthy: the Lenovo ThinkServer firmware accommodates the string “DO NOT TRUST” embedded throughout the Platform Key (PK). To higher perceive the place this originates, analyst can load the identical firmware picture into CERT UEFI Parser’s GUI view.
From the JSON output in Determine 1, we establish the PK as an X.509 DER certificates and use this class identify to look within the GUI. As proven in Determine 2, the search locates the corresponding hex area containing the identical “DO NOT TRUST” string.
Determine 2 CERT UEFI Parser in GUI mode helps looking out by Class Title. A hex dump is exhibited to the appropriate of the parsed courses.
The decoded hexadecimal values within the backside proper of the picture additionally learn “DO NOT TRUST.” Zooming in:
Determine 3 A closeup of the hex dump in CERT UEFI Parser GUI mode
This examination course of reveals how CERT UEFI Parser can precisely visualize the internals of a UEFI ROM, expediting evaluation and vulnerability discovery. A researcher might use CERT UEFI Parser to additional study ROMs both in an automatic means utilizing JSON output or interactively examine utilizing the GUI to examine binary recordsdata similar to firmware, installers and such.
The UEFI Ecosystem
Earlier than UEFI was EFI, and earlier than EFI was BIOS. Within the BIOS-dominated period, restricted standardization made it tough to help more and more advanced and dynamic {hardware} environments. Intel created EFI to handle this battle, and UEFI is its “unified” successor bringing supply-chain events and their interactions into some widespread fairly outlined interfaces.
UEFI requirements have been revealed to deliver such uniformity to the system software program layer that bridges {hardware} and working methods, whereas nonetheless permitting for innovation and implementation flexibility. As these requirements have been adopted, the UEFI group emerged below the Unified Extensible Firmware Interface Discussion board as a free collaboration of silicon distributors, platform producers, firmware builders, working system distributors, and gear builders who collectively interpret, implement, and lengthen the specification.
In observe, the UEFI ecosystem will not be a single implementation, however a large assortment of firmware codebases, configuration selections, and vendor-specific extensions deployed throughout globally manufactured methods. Whereas widespread interfaces allow interoperability, real-world implementations differ considerably as a result of differing design priorities, legacy necessities, and ranges of engineering rigor.
This variability creates an setting the place correctness and safety can’t be assumed. Misinterpretations of the specification, delicate defects, configuration errors, and unintended interactions might exist beneath the working system’s visibility, significantly in security-sensitive paths. For that reason, systematic evaluation and reverse engineering of UEFI implementations by safety evaluators stay obligatory to grasp precise conduct, establish gaps, and validate safety assumptions throughout the broader UEFI ecosystem.
Future UEFI work on the SEI
CERT UEFI Parser is at a transition stage, and its future is basically depending on group engagement within the type of suggestions, function requests, and direct contributions. Enhancing UEFI transparency requires sustained, collaborative effort. We encourage readers to go to our GitHub web page, discover the parser, share suggestions, request new options, or contribute enhancements by means of pull requests; such participation will assist us refine and increase the software, bringing higher maturity and visibility to firmware evaluation throughout the ecosystem.
The SEI continues to make use of the parser for analysis in systemic vulnerabilities, along with our work constructing instruments and strategies to assist cybersecurity professionals consider UEFI safety weaknesses. The advanced, opaque, and privileged nature of UEFI firmware stays an underappreciated supply of danger that warrants elevated scrutiny.
