CVE-2024-28905 is a high-severity elevation of privilege vulnerability affecting Microsoft Windows Server 2022, specifically the 23H2 Edition with Server Core installation. The vulnerability arises from improper privilege management within the Microsoft Brokering File System component. This flaw is classified under CWE-269, which pertains to improper privilege management, indicating that the system fails to adequately enforce access controls or privilege boundaries. Exploiting this vulnerability allows an attacker with limited privileges (low-level privileges) to escalate their privileges to a higher level, potentially SYSTEM or administrative level, thereby gaining full control over the affected server. The vulnerability has a CVSS 3.1 base score of 7.8, reflecting a high severity due to its impact on confidentiality, integrity, and availability (all rated high), the requirement for local access (AV:L), high attack complexity (AC:H), and the need for low privileges (PR:L) but no user interaction (UI:N). The scope is changed (S:C), meaning the vulnerability affects resources beyond the initially compromised component. Notably, there are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability affects version 10.0.25398.0 of Windows Server 2022 23H2 Server Core, a minimal installation option commonly used in enterprise environments for running server roles with reduced attack surface. The improper privilege management in the brokering file system could allow an attacker to bypass security restrictions, manipulate sensitive files, or execute arbitrary code with elevated privileges, severely compromising the server's security posture.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and service providers relying on Windows Server 2022 23H2 Server Core installations for critical infrastructure, cloud services, and internal applications. Successful exploitation could lead to full system compromise, data breaches involving sensitive or regulated information, disruption of business operations, and potential lateral movement within corporate networks. Given the high impact on confidentiality, integrity, and availability, attackers could exfiltrate data, deploy ransomware, or sabotage services. The requirement for local access limits remote exploitation but does not eliminate risk, as attackers might leverage other vulnerabilities or social engineering to gain initial foothold. The Server Core installation is popular in data centers and cloud environments across Europe, meaning that critical sectors such as finance, healthcare, government, and manufacturing could be affected. The absence of known exploits currently provides a window for proactive mitigation, but the high severity score indicates that exploitation could have severe consequences.

1. Immediate deployment of any forthcoming official patches or security updates from Microsoft once available is critical. 2. Until patches are released, restrict local access to Windows Server 2022 23H2 Server Core systems by enforcing strict access controls, including the use of multi-factor authentication for administrative accounts and limiting physical and remote console access. 3. Implement robust monitoring and logging of privilege escalation attempts and unusual file system activities related to the brokering file system component. 4. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious behavior indicative of privilege escalation. 5. Conduct regular audits of user privileges and remove unnecessary local accounts or privileges to reduce the attack surface. 6. Segment critical servers from general user networks to limit lateral movement opportunities. 7. Educate system administrators about this vulnerability and encourage vigilance for signs of compromise. 8. Consider temporary disabling or restricting use of the brokering file system component if feasible and if it does not impact essential services, pending patch deployment.