CVE-2024-28920 is a high-severity vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). It involves a Protection Mechanism Failure (CWE-693) specifically targeting the Secure Boot security feature. Secure Boot is a critical security component designed to ensure that only trusted, signed software is loaded during the system startup process, preventing unauthorized or malicious code from executing early in the boot sequence. This vulnerability allows an attacker with limited privileges (local access with low privileges) to bypass Secure Boot protections without requiring user interaction. The CVSS 3.1 base score of 7.8 reflects the significant impact on confidentiality, integrity, and availability, as exploitation can lead to full system compromise. The attack vector is local (AV:L), requiring the attacker to have some level of access to the system, but no user interaction is needed (UI:N). The vulnerability does not require elevated privileges to exploit (PR:L), making it more accessible to attackers who have gained limited access. The scope remains unchanged (S:U), meaning the impact is confined to the vulnerable system. Although no known exploits are currently reported in the wild, the vulnerability's nature suggests that once exploited, it could allow attackers to load malicious bootloaders or kernel-level malware, effectively bypassing Secure Boot protections and undermining the system's trust chain. This could facilitate persistent malware infections, rootkits, or unauthorized firmware modifications, severely compromising system security.

For European organizations, especially those relying on Windows 10 Version 1809 in critical infrastructure, government, finance, healthcare, and industrial sectors, this vulnerability poses a substantial risk. The Secure Boot bypass could enable attackers to implant persistent malware that survives OS reinstalls and evades traditional detection mechanisms. This undermines endpoint security, potentially leading to data breaches, intellectual property theft, disruption of services, and loss of trust. Organizations with legacy systems still running this Windows version are particularly vulnerable, as they may lack the latest security updates and mitigations. The high confidentiality, integrity, and availability impact means that attackers could exfiltrate sensitive data, alter system configurations, or cause system outages. Given the local attack vector, insider threats or attackers who have gained limited access through phishing or lateral movement could escalate their control significantly. The absence of known exploits in the wild currently provides a window for proactive defense, but the vulnerability's severity demands urgent attention to prevent exploitation.

1. Immediate upgrade or patching: Although no specific patch links are provided, organizations should prioritize upgrading affected systems to a supported and fully patched Windows version beyond 1809, ideally Windows 10 21H2 or later, or Windows 11, where Secure Boot protections are enhanced. 2. Restrict local access: Limit local user privileges and enforce strict access controls to reduce the risk of attackers gaining the required local access to exploit this vulnerability. 3. Implement Endpoint Detection and Response (EDR): Deploy advanced EDR solutions capable of detecting anomalous bootloader or kernel-level activities that may indicate Secure Boot bypass attempts. 4. Monitor firmware and boot integrity: Use hardware-based attestation and integrity measurement tools to detect unauthorized changes to boot components. 5. Harden physical security: Prevent unauthorized physical access to devices, as local access is a prerequisite for exploitation. 6. Conduct regular audits: Identify and remediate legacy systems still running Windows 10 Version 1809, and plan for their timely upgrade or decommissioning. 7. User training and awareness: Educate users about the risks of privilege escalation and the importance of reporting suspicious system behavior. 8. Network segmentation: Isolate critical systems to limit lateral movement opportunities for attackers who gain local access.