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Microsoft’s Threat Intelligence team has utilized its AI-driven Security Copilot tool to uncover 20 severe vulnerabilities within commonly used open-source bootloaders — specifically, GRUB2, U-Boot, and Barebox.
These bootloaders play an essential role in initializing operating systems, particularly for Linux-based platforms and embedded systems. The vulnerabilities discovered impact systems that implement Unified Extensible Firmware Interface (UEFI) Secure Boot, which includes various Internet of Things (IoT) devices, cloud infrastructure, and enterprise IT setups.
Among the vulnerabilities is a significant integer overflow problem, which could potentially allow attackers to execute arbitrary code. In the case of GRUB2, this could enable malicious actors to bypass Secure Boot, insert covert bootkits, and circumvent enterprise security features like BitLocker encryption, as highlighted in a blog post from Microsoft’s Threat Intelligence team here.
“The ramifications of deploying such bootkits are serious, providing threat actors with total control over the device, influencing the boot process, compromising the operating system, infiltrating additional devices on the network, and facilitating a range of malevolent activities,” Microsoft noted.
This situation raises significant alarms for organizations that rely on Secure Boot to ensure device integrity and protect their systems. Microsoft emphasized that the vulnerabilities are especially alarming because successful exploitation could lead to persistent threats that are challenging to eliminate.
Concerns over persistent malware
While gaining access to U-Boot or Barebox vulnerabilities might require physical access to devices, the flaws within GRUB2 pose a more immediate threat to enterprises. The most worrisome element, according to Microsoft, is the potential for creating malware that persists even after an operating system is reinstalled or a hard drive is replaced.
“These vulnerabilities in bootloaders, particularly in GRUB2, are critical because they allow attackers to embed malware that remains operational even after an OS reinstall or storage replacement,” stated Prabhjyot Kaur, a senior analyst at Everest Group. “Sectors with high-security needs, such as government, finance, healthcare, and critical infrastructure, must prioritize immediate remediation.”
This capacity for persistence makes these vulnerabilities particularly hazardous, as conventional remediation strategies would likely fail against such deeply entrenched threats. Organizations with extensive Linux environments or IoT device networks should be particularly vigilant.
Microsoft has informed all relevant bootloader maintainers about these vulnerabilities and worked collaboratively to develop patches. Security updates were rolled out in mid-February 2025, with GRUB2 patches available as of February 18 and subsequent patches for U-Boot and Barebox released on February 19, according to the blog.
AI-powered discovery changes the cybersecurity landscape
Microsoft’s Security Copilot tool has significantly expedited the process of vulnerability identification, particularly targeting filesystem implementations due to their high propensity for vulnerabilities.
“Utilizing Security Copilot, we identified potential security issues within bootloader functionalities, especially focusing on filesystems which are often highly vulnerable,” the blog noted. “This methodology saved our team around a week that would have otherwise been spent on manual reviews.”
Through strategically designed prompts, Security Copilot revealed an exploitable integer overflow vulnerability and assisted in the detection of similar vulnerability patterns across multiple files.
“We are sharing this research to demonstrate the enhanced efficiency, streamlined workflows, and improved capabilities that AI tools like Security Copilot can deliver for defenders, security researchers, and Security Operations Center (SOC) analysts,” the blog emphasized.
“We are witnessing a major shift from the traditional responsible disclosure approach to a more dynamic environment,” said Sunil Varkey, an advisor at Beagle Security. “With AI now identifying vulnerabilities at such a rapid pace, we can expect to see a surge in zero-day vulnerabilities.”
Varkey characterized an evolving scenario where “all parties — both defenders and attackers — are aware of vulnerabilities at the same time. It creates a volatile situation akin to a Wild West, where preparation for this accelerated pace of discovery is lacking for many defenders.”
“AI can evaluate extensive codebases, spot memory handling patterns, and propose fixes at speeds far beyond manual analysis capabilities,” Kaur mentioned. “While defenders benefit from quicker response times, attackers are also harnessing AI, creating a relentless arms race between both sides.”
As AI tools gain importance for both parties, Microsoft underscored the necessity of sharing information among security vendors and researchers to maintain a security edge.
“For years, the cybersecurity battlefield has been lopsided,” stated Gogia. “Attackers had the advantage of time, creativity, and fewer restrictions. Defenders were often overwhelmed, reactive, and inundated with alerts. However, AI is altering that balance.”
Implications for enterprise security
For enterprise security teams, these discoveries accentuate the need for keeping firmware and bootloaders updated—areas that are often neglected in standard patch management processes. Organizations should reassess their vulnerability management programs to ensure comprehensive coverage of these components.
These vulnerabilities also highlight the persistent risks linked with supply chain security, given that many organizations may be utilizing these bootloaders without fully understanding the underlying components.
Security experts recommend organizations conduct inventories of affected systems, prioritize the application of February 2025 security updates, implement monitoring for exploitation attempts, and establish review processes to include bootloaders in regular security maintenance.
“Organizations ought to establish policies explicitly addressing firmware and bootloader updates, maintain hardware inventories detailing which systems employ affected bootloaders, and integrate these lower-level components into existing patch management cycles,” Kaur advised.
Addressing bootloader vulnerabilities presents distinct challenges, according to Varkey. “Mitigating such vulnerabilities at the firmware level is crucial, but it comes with significant challenges. Mitigation patches are often scarce, influenced heavily by the prioritization of OEM vendors — similar to issues faced with Operational Technology (OT) devices and other firmware.” He further noted that “many known vulnerabilities go unacknowledged or unpatched by vendors. The only recourse in such cases is to implement perimeter protections or enhance access control measures.”
Source
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