CVE-2024-28904 is a high-severity elevation of privilege vulnerability affecting Microsoft Windows Server 2022, specifically the 23H2 Edition with Server Core installation. The vulnerability is classified under CWE-269, indicating improper privilege management. It arises within the Microsoft Brokering File System component, which is responsible for managing file system operations and access brokering between processes. Due to improper handling of privilege checks, a low-privileged user or process with limited access rights (PR:L) can exploit this flaw to elevate their privileges to a higher level, potentially SYSTEM or administrative privileges. The vulnerability has a CVSS 3.1 base score of 7.8, reflecting its significant impact on confidentiality, integrity, and availability (all rated high). The attack vector is local (AV:L), requiring the attacker to have local access to the system, and it demands high attack complexity (AC:H), meaning exploitation is non-trivial and likely requires specific conditions or knowledge. No user interaction is needed (UI:N), and the scope is changed (S:C), indicating that the vulnerability affects resources beyond the initially compromised component. Although no known exploits are currently reported in the wild, the vulnerability’s potential impact is critical for environments relying on Windows Server 2022 Server Core installations, which are commonly used in enterprise and data center environments for their minimal footprint and enhanced security posture. The lack of available patches at the time of publication necessitates immediate attention to mitigation strategies to reduce risk exposure.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and service providers utilizing Windows Server 2022 Server Core installations for critical infrastructure, cloud services, and internal enterprise applications. Successful exploitation could allow attackers with limited local access to escalate privileges, potentially leading to full system compromise, unauthorized data access, disruption of services, and lateral movement within networks. This is particularly concerning for sectors with stringent data protection requirements such as finance, healthcare, and government institutions. The elevated privileges could enable attackers to disable security controls, exfiltrate sensitive information, or deploy ransomware. Given the Server Core installation’s prevalence in streamlined, security-focused deployments, the vulnerability undermines the expected security benefits of this configuration. Additionally, the changed scope of the vulnerability means that the impact could extend beyond the initially compromised process, affecting other system components and services, thereby amplifying the potential damage.

1. Restrict local access: Limit the number of users with local access to Windows Server 2022 Server Core systems to only trusted administrators and essential personnel. 2. Employ strict access controls and monitoring: Implement enhanced auditing and monitoring of privilege escalation attempts and unusual file system brokering activities. 3. Use application whitelisting and endpoint protection: Deploy advanced endpoint detection and response (EDR) solutions capable of detecting anomalous privilege escalation behaviors. 4. Network segmentation: Isolate critical servers to minimize the risk of lateral movement if an attacker gains local access. 5. Apply principle of least privilege: Ensure that service accounts and users operate with the minimum privileges necessary to perform their functions. 6. Stay updated on patches: Although no patches were available at the time of disclosure, organizations should monitor Microsoft’s security advisories closely and apply updates immediately upon release. 7. Consider temporary compensating controls such as disabling or restricting the Microsoft Brokering File System component if feasible and if it does not disrupt critical operations. 8. Conduct regular security assessments and penetration testing focused on privilege escalation vectors to identify and remediate potential exploitation paths.