CVE-2024-20666 is a vulnerability identified in Microsoft Windows 10 Version 1809, specifically affecting build 10.0.17763.0. The vulnerability is categorized under CWE-20, which relates to improper input validation. This flaw impacts the BitLocker security feature, a full disk encryption technology designed to protect data by providing encryption for entire volumes. The vulnerability allows a security feature bypass, meaning an attacker with limited privileges (low privileges required) could exploit improper input validation to potentially compromise the confidentiality, integrity, and availability of the encrypted data. The CVSS v3.1 base score is 6.6, indicating a medium severity level. The vector details specify that the attack requires physical or local access (Attack Vector: Physical), low attack complexity, and low privileges, with no user interaction needed. The scope is unchanged, but the impact on confidentiality, integrity, and availability is high, suggesting that successful exploitation could lead to significant data exposure or manipulation. No known exploits are currently reported in the wild, and no patches or mitigation links have been provided yet. This vulnerability highlights a critical weakness in the input validation mechanisms within BitLocker, potentially allowing attackers to bypass encryption protections under certain conditions.

For European organizations, the impact of this vulnerability could be significant, especially for entities relying on Windows 10 Version 1809 with BitLocker enabled for data protection. Organizations in sectors such as finance, healthcare, government, and critical infrastructure that handle sensitive personal data and intellectual property could face data breaches or unauthorized data access. The bypass of BitLocker encryption undermines the trust in data confidentiality and could lead to regulatory non-compliance under GDPR, resulting in legal and financial penalties. Additionally, the integrity and availability of data could be compromised, affecting business continuity and operational security. Since the attack vector requires physical or local access, the threat is more pronounced in environments where devices are shared, lost, or stolen, such as mobile workforces or organizations with less stringent physical security controls. The medium severity rating suggests that while exploitation is not trivial, the consequences of a successful attack are severe, warranting immediate attention to affected systems.

Given the absence of official patches at the time of this report, European organizations should implement specific mitigations beyond generic advice: 1) Restrict physical access to devices running Windows 10 Version 1809 with BitLocker enabled, including enforcing strict device control policies and secure storage for laptops and removable drives. 2) Employ multi-factor authentication and strong pre-boot authentication methods for BitLocker to add layers of security beyond the vulnerable input validation. 3) Monitor and audit local access logs and device usage to detect any unauthorized physical access attempts. 4) Consider upgrading affected systems to a more recent, supported Windows version where this vulnerability is addressed or mitigated. 5) Use endpoint detection and response (EDR) tools to identify suspicious activities related to BitLocker or encryption bypass attempts. 6) Educate users about the risks of device loss or theft and enforce policies for immediate reporting and response. 7) Implement full disk encryption solutions with proven resilience and regularly review encryption configurations to ensure compliance with best practices.