CVE-2024-20669 is a vulnerability identified in Microsoft Windows 10 Version 1809, specifically affecting build 10.0.17763.0. The vulnerability is classified under CWE-693, which pertains to Protection Mechanism Failure. This particular flaw involves a bypass of the Secure Boot security feature, a critical component designed to ensure that only trusted software is loaded during the system startup process. Secure Boot is a UEFI firmware feature that prevents unauthorized or malicious code from running before the operating system loads, thereby protecting the system from rootkits and bootkits. The vulnerability allows an attacker with high privileges (PR:H) and local access (AV:L) to bypass this protection mechanism without requiring user interaction (UI:N). The CVSS v3.1 base score is 6.7, indicating a medium severity level. The impact includes potential compromise of confidentiality, integrity, and availability, as the attacker could execute unauthorized code early in the boot process, potentially gaining persistent control over the system. However, exploitation requires local access and elevated privileges, which limits the attack vector. There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability was reserved in late November 2023 and published in April 2024, indicating recent discovery and disclosure. The lack of a patch and the critical role of Secure Boot in system security make this a significant concern for affected systems still running this older Windows 10 version.

For European organizations, the impact of this vulnerability can be substantial, especially for those that continue to operate legacy systems running Windows 10 Version 1809. Successful exploitation could allow attackers to bypass Secure Boot protections, leading to the execution of malicious code at boot time, potentially resulting in persistent malware infections, data breaches, or system integrity compromise. This can affect critical infrastructure, government agencies, financial institutions, and enterprises that rely on secure boot processes to maintain system trustworthiness. The requirement for local high-privilege access reduces the risk of remote exploitation but raises concerns about insider threats or attackers who have already gained initial footholds. The vulnerability could also complicate incident response and recovery efforts, as malware operating below the OS level is difficult to detect and remove. Given the medium severity and the absence of known exploits, the immediate risk is moderate, but the potential for future exploitation remains, especially if attackers develop techniques to escalate privileges or gain local access.

Organizations should prioritize upgrading affected systems to supported Windows versions that have addressed this vulnerability, as no patches are currently linked for Windows 10 Version 1809. Implement strict access controls to limit local administrative privileges and reduce the risk of privilege escalation. Employ endpoint detection and response (EDR) solutions capable of detecting anomalous boot-level activities. Regularly audit and monitor systems for unauthorized changes to boot configurations or firmware settings. Consider deploying hardware-based security features such as TPM (Trusted Platform Module) and ensure Secure Boot is enabled and properly configured. For environments where upgrading is not immediately feasible, implement network segmentation and strict physical security controls to prevent unauthorized local access. Maintain up-to-date backups and have incident response plans that include recovery from boot-level compromises.