CVE-2024-37986 is a vulnerability classified under CWE-191 (Integer Underflow) that affects Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability specifically targets the Secure Boot security feature, which is designed to ensure that only trusted software is loaded during the system startup process. An integer underflow occurs when an arithmetic operation causes a value to wrap around below its minimum representable value, potentially leading to unexpected behavior. In this case, the underflow can be exploited by an attacker to bypass Secure Boot protections, effectively undermining the integrity guarantees Secure Boot provides. The CVSS 3.1 base score is 8.0 (high), with an attack vector of adjacent network (AV:A), low attack complexity (AC:L), no privileges required (PR:N), and requiring user interaction (UI:R). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). This means an attacker can remotely induce the vulnerability with minimal complexity and no credentials, but some user interaction is necessary, such as convincing a user to open a malicious file or link. The vulnerability is currently published but no patches or known exploits are reported yet. The lack of a patch link indicates that remediation may require monitoring for forthcoming updates or applying mitigations such as disabling Secure Boot or restricting network access to vulnerable systems. The vulnerability's exploitation could allow attackers to bypass Secure Boot, potentially enabling persistent malware or rootkits that load before the OS, severely compromising system security.

For European organizations, the impact of this vulnerability is significant due to the critical role Secure Boot plays in protecting system integrity and preventing unauthorized code execution during boot. Exploitation could allow attackers to bypass Secure Boot protections, facilitating the installation of persistent, stealthy malware or rootkits that evade detection by traditional security tools. This could lead to full system compromise, data breaches, disruption of services, and loss of trust in IT infrastructure. Sectors such as finance, healthcare, government, and critical infrastructure are particularly vulnerable due to their reliance on Windows 10 systems and the importance of maintaining secure boot integrity. The requirement for user interaction means phishing or social engineering could be used to trigger the exploit, increasing risk in environments with less stringent user awareness. The absence of known exploits in the wild currently reduces immediate risk but does not diminish the urgency for mitigation given the high severity and potential impact. Organizations running legacy Windows 10 Version 1809 systems face heightened exposure, especially if these systems are connected to networks accessible by attackers.

1. Immediately inventory and identify all systems running Windows 10 Version 1809 (build 10.0.17763.0) within the organization. 2. Monitor Microsoft security advisories closely for the release of patches addressing CVE-2024-37986 and apply them promptly once available. 3. Until patches are released, consider disabling Secure Boot on affected systems if operationally feasible, understanding this reduces security but prevents exploitation of this specific vulnerability. 4. Restrict network access to vulnerable systems, especially from untrusted or external networks, to reduce the attack surface. 5. Enhance user awareness training focusing on phishing and social engineering risks to mitigate the user interaction requirement for exploitation. 6. Implement endpoint detection and response (EDR) solutions capable of detecting anomalous boot processes or unauthorized firmware modifications. 7. Plan and execute an upgrade strategy to move systems off Windows 10 Version 1809 to supported, patched Windows versions with improved security features. 8. Employ network segmentation to isolate critical systems and limit lateral movement in case of compromise. 9. Regularly back up critical data and verify recovery procedures to mitigate impact of potential attacks exploiting this vulnerability.