CVE-2024-37981 is a high-severity integer underflow vulnerability (CWE-191) affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw resides in the Secure Boot security feature, which is designed to ensure that only trusted software is loaded during the system boot 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 or memory corruption. In this case, the underflow can be exploited to bypass Secure Boot protections, undermining the integrity of the boot process and allowing an attacker to load unauthorized or malicious code before the operating system starts. The vulnerability requires network access (Attack Vector: Adjacent), no privileges, but does require user interaction, and it affects confidentiality, integrity, and availability with high impact. Although no known exploits are currently in the wild, the vulnerability's existence in a critical security feature makes it a significant threat. The lack of available patches at the time of publication increases the urgency for mitigation. This vulnerability could be leveraged by attackers to establish persistent, stealthy footholds on affected systems, potentially leading to full system compromise and evasion of endpoint security controls that rely on Secure Boot for trust verification.

For European organizations, this vulnerability poses a substantial risk, especially for enterprises and government agencies relying on Windows 10 Version 1809 in their infrastructure. The bypass of Secure Boot can facilitate advanced persistent threats (APTs), ransomware deployment, and supply chain attacks by allowing malicious code to execute early in the boot process, evading detection by traditional security solutions. Critical sectors such as finance, healthcare, energy, and public administration could face severe confidentiality breaches, data integrity violations, and operational disruptions. The high impact on availability could result in system outages or forced downtime for remediation. Given that Windows 10 Version 1809 is an older release, some organizations may still be running it due to legacy application dependencies, increasing their exposure. The requirement for user interaction suggests that social engineering or phishing could be used as an attack vector, further broadening the threat landscape. The absence of known exploits in the wild currently offers a window for proactive defense, but the potential for rapid weaponization remains high.

European organizations should prioritize upgrading affected systems to a supported and patched version of Windows, ideally moving away from Windows 10 Version 1809 to a more recent release with active security updates. In the interim, organizations should enforce strict network segmentation and limit exposure of vulnerable systems to untrusted networks to reduce the attack surface. Implementing robust endpoint detection and response (EDR) solutions that monitor for anomalous boot-time activities can help detect exploitation attempts. User awareness training should be enhanced to mitigate the risk of social engineering attacks that could trigger the vulnerability. Additionally, organizations should audit and enforce Secure Boot configurations via Group Policy or management tools to ensure Secure Boot is enabled and properly configured. Monitoring for unusual firmware or bootloader modifications can also provide early warning signs. Finally, organizations should subscribe to vendor advisories and threat intelligence feeds to apply patches promptly once they become available.