Microsoft’s AI-powered Security Copilot has identified 20 previously unknown security vulnerabilities in popular open-source bootloaders, potentially affecting millions of devices worldwide.

## Critical Bootloader Flaws Discovered

The vulnerabilities were found in three widely-used bootloaders:
– GRUB2 (GRand Unified Bootloader): The default bootloader for most Linux distributions including Ubuntu
– U-Boot and Barebox: Commonly used in embedded systems and IoT devices

The 11 GRUB2 vulnerabilities include integer and buffer overflows in filesystem parsers, command flaws, and cryptographic comparison issues. Meanwhile, 9 buffer overflow vulnerabilities were discovered in U-Boot and Barebox related to parsing SquashFS, EXT4, CramFS, JFFS2, and symlinks.

## Security Implications

These flaws impact devices relying on UEFI Secure Boot and could allow attackers to bypass critical security protections. Microsoft warns that successful exploitation could enable:
– Installation of stealthy bootkits
– Complete control over affected devices
– Persistence even after OS reinstallation or hard drive replacement
– Network compromise of additional devices

While U-Boot and Barebox vulnerabilities typically require physical access, GRUB2 flaws could potentially be exploited remotely through malware infections, similar to previous bootkit attacks like BlackLotus.

## AI-Powered Discovery

Microsoft reports that Security Copilot dramatically accelerated the vulnerability discovery process, saving approximately one week compared to manual analysis. The AI tool not only identified the flaws but also provided targeted mitigation recommendations to expedite security patches.

## Mitigation

Security updates addressing these vulnerabilities were released in February 2025. Users and administrators should update to the latest versions of GRUB2, U-Boot, and Barebox to mitigate these security risks.