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Security researchers at Binarly and others have uncovered a dangerous Secure Boot bypass vulnerability (CVE-2025-3052) in a module signed with Microsoft’s official certificate. This flaw allows attackers to disable Secure Boot, compromising system trust before the operating system even loads.
How Secure Boot Bypass Works In Firmware
The affected tool, typically used for BIOS updates, misuses the NVRAM variable IhisiParamBuffer as a pointer for memory writes. Critically, it lacks proper validation. This loophole enables attackers to overwrite the gSecurity2 flag, which enforces Secure Boot. Once this flag is disabled, Secure Boot no longer functions, exposing the system to deep-level attacks.
Why This Secure Boot Bypass Is So Dangerous
This vulnerability is especially severe because it enables firmware-level malware infections, often referred to as bootkits. These threats live below the operating system layer, making them extremely difficult to detect or remove. Even antivirus and endpoint detection tools are unlikely to catch them, and they can survive full system reinstalls and reboots.
Devices At Risk
Any system that relies on Microsoft’s UEFI CA 2011 certificate could be at risk. This includes most modern Windows machines and many Linux systems that utilize shim bootloaders. Researchers also discovered 13 other firmware modules with similar flaws, potentially affecting over 50 different hardware models from various vendors.
Microsoft Issues Patch With Urgent Update
As part of June 2025 Patch Tuesday, Microsoft blacklisted all 14 affected firmware modules using the Secure Boot forbidden database, known as the dbx. This revocation is a critical step. Without it, even if Secure Boot appears enabled in the OS, the protection is meaningless due to the underlying firmware flaw.
Additional Secure Boot Bypass Flaws Emerge
Researchers at Eclypsium also reported a related vulnerability named “Hydroph0bia” (CVE-2025-47827), found in Insyde H2O firmware. It too leverages unvalidated NVRAM variable manipulation to bypass Secure Boot. These discoveries signal a growing trend of attackers targeting the firmware layer and exploiting supply chain weaknesses.
Remedies To Do
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Install June 2025 Windows updates immediately.
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Review UEFI dbx entries to confirm revocations are applied.
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Monitor firmware for integrity and unusual NVRAM usage.
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Work with hardware vendors to apply available firmware updates.
This latest Secure Boot bypass shows that even trusted, signed firmware components can become weapons in the wrong hands. It underlines the importance of regular updates, firmware visibility, and adopting a defense-in-depth approach to system security.
