As just lately as December 2025, the SEI’s CERT Coordination Heart (CERT/CC) documented a UEFI-related vulnerability in sure motherboard fashions, illustrating that early-boot firmware habits continues to current safety challenges regardless of requiring native bodily entry to take advantage of. 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 assist assaults which might be notably troublesome to detect and mitigate.
This vulnerability is the newest challenge reported, however it’s not 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 critical given the extraordinarily excessive privileges UEFI firmware possesses. Equally essential, UEFI firmware is commonly massive, complicated, and opaque, which makes it difficult to research for safety considerations.
On the SEI we’ve made the invention and remediation of UEFI vulnerabilities a precedence. On this weblog put up, 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 venture aimed toward creating a standard bootloader for all fashionable computing gadgets. It replaces the standard 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 totally 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. Nevertheless, the place there’s software program, there’s the likelihood for vulnerabilities and exploits.
CERT started growing 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 among the most invisible and difficult-to-manage ecosystems in fashionable computing. We use the time period “systemic vulnerability” to explain a deeply embedded flaw that’s pervasive throughout a number of techniques, distributors, or implementations; troublesome to detect or remediate because of complicated dependencies and elusive root causes; and infrequently dismissed as inherent to the system itself. The UEFI ecosystem exemplifies this definition. Firmware is difficult to examine, inconsistently documented, and difficult to handle throughout various {hardware} platforms, which makes vulnerabilities each troublesome to find and much more obscure when it comes to their broader impression.
Early analysis in UEFI vulnerabilities uncovered a labyrinth of information 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 complicated customized codecs that stay outdoors conventional executable file codecs, equivalent to Microsoft’s Moveable Executable (PE) or the Executable and Linkable Format (ELF) generally utilized by Linux techniques. These parts are sometimes undocumented, extremely vendor-specific, and out of doors 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 totally different initiatives. For instance, when a flaw was disclosed in a selected firmware construct, it was usually unclear how a lot of the underlying code was reused in different UEFI initiatives. With out a constant method to rapidly parse and examine elements, figuring out the listing of affected fashions for a vulnerability was extraordinarily troublesome. It was quickly apparent that we would have liked 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 recuperate the construction obligatory to research and perceive binary artifacts. Efficient parsing have to be environment friendly and correct, incrementally decoding firmware binaries into higher-level constructions that assist exploration and evaluation. Constructed on utilizing such strong and extensible parsing frameworks, CERT UEFI Parser provides researchers, system directors, and safety fanatics a strong and clear method to examine and analyze firmware. Its options embrace the capabilities to:
- Decompose firmware pictures, expose hidden constructions, and assist deeper reverse engineering and code-reuse evaluation throughout the various UEFI panorama
- parse firmware ROMs, UEFI firmware pictures, PE recordsdata, installer packages, and extra
- assist 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 accrued analysis into how the firmware is constructed, the way it varies throughout distributors, and the way it may be analyzed extra systematically.
Case Examine: Investigating the PKFail Vulnerability
Contemplate the PKFail vulnerability, revealed in August 2024. Within the PKFail vulnerability, Platform Keys (PKs) utilized in improvement 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 via how somebody would possibly 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, equivalent 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 incorporates 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 best 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 may use CERT UEFI Parser to additional look at ROMs both in an automatic approach utilizing JSON output or interactively examine utilizing the GUI to examine binary recordsdata equivalent 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 troublesome to assist more and more complicated and dynamic {hardware} environments. Intel created EFI to deal with 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 techniques, whereas nonetheless permitting for innovation and implementation flexibility. As these requirements have been adopted, the UEFI neighborhood emerged underneath the Unified Extensible Firmware Interface Discussion board as a free collaboration of silicon distributors, platform producers, firmware builders, working system distributors, and power builders who collectively interpret, implement, and lengthen the specification.
In apply, the UEFI ecosystem is just not a single implementation, however a large assortment of firmware codebases, configuration selections, and vendor-specific extensions deployed throughout globally manufactured techniques. Whereas widespread interfaces allow interoperability, real-world implementations differ considerably because of differing design priorities, legacy necessities, and ranges of engineering rigor.
This variability creates an surroundings the place correctness and safety can’t be assumed. Misinterpretations of the specification, refined defects, configuration errors, and unintended interactions could exist under the working system’s visibility, notably in security-sensitive paths. Because of this, systematic evaluation and reverse engineering of UEFI implementations by safety evaluators stay obligatory to grasp precise habits, 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 essentially depending on neighborhood engagement within the type of suggestions, function requests, and direct contributions. Bettering 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 via pull requests; such participation will assist us refine and develop 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 complicated, opaque, and privileged nature of UEFI firmware stays an underappreciated supply of threat that warrants elevated scrutiny.