CVE-2024-39875 is a medium-severity vulnerability affecting Siemens SINEMA Remote Connect Server versions prior to 3.2 SP1. The vulnerability is categorized under CWE-732, which pertains to incorrect permission assignment for critical resources. Specifically, this flaw allows authenticated users with low privilege—those granted the 'Manage own remote connections' permission—to access information about other users and their group memberships within the system. This permission scope is intended to restrict users to managing only their own remote connections, but due to improper access control enforcement, these users can enumerate details beyond their authorization boundaries. The vulnerability does not require user interaction beyond authentication and can be exploited remotely over the network (AV:N). The attack complexity is low (AC:L), and no elevated privileges beyond the assigned low privilege are needed (PR:L). The vulnerability impacts confidentiality (C:L) but does not affect integrity or availability. The scope remains unchanged (S:U), meaning the impact is limited to the vulnerable component without affecting other system components. The exploitability is partially functional (E:P), and the vulnerability has an official remediation level of 'Official Fix' (RL:O) with a confirmed report confidence (RC:C). No known exploits are currently reported in the wild. SINEMA Remote Connect Server is a critical industrial communication management product used primarily in industrial automation and control systems to manage remote connections securely. The exposure of user and group membership information could facilitate reconnaissance activities by threat actors, potentially enabling further targeted attacks or privilege escalation attempts if combined with other vulnerabilities or social engineering. However, the vulnerability itself does not allow direct system compromise or disruption.

For European organizations, especially those operating in industrial sectors such as manufacturing, energy, utilities, and critical infrastructure, this vulnerability poses a moderate confidentiality risk. Disclosure of user and group membership information can aid attackers in mapping the internal network structure and user roles, which is valuable intelligence for planning more sophisticated attacks. While the vulnerability does not directly compromise system integrity or availability, the leakage of sensitive user information can undermine trust and compliance with data protection regulations such as GDPR. Organizations relying on Siemens SINEMA Remote Connect Server for remote management of industrial control systems may face increased risk of targeted attacks if adversaries leverage this information to identify privileged accounts or weak points in access control. The impact is more pronounced in environments where user role segregation is critical and where insider threat or external attackers with valid credentials are plausible. Given the industrial context, any compromise or lateral movement facilitated by this vulnerability could eventually lead to operational disruptions or safety hazards, although this vulnerability alone does not enable such outcomes.

1. Upgrade to Siemens SINEMA Remote Connect Server version 3.2 SP1 or later, where this vulnerability has been addressed. 2. Review and tighten user permission assignments, ensuring that only necessary users have the 'Manage own remote connections' permission and that this permission is not granted broadly. 3. Implement strict network segmentation and access controls to limit which users can authenticate to the SINEMA Remote Connect Server, reducing the attack surface. 4. Monitor and audit user activities and access logs for unusual enumeration or access patterns that could indicate exploitation attempts. 5. Employ multi-factor authentication (MFA) for all users accessing the system to reduce the risk of credential misuse. 6. Conduct regular security awareness training focused on social engineering risks that could leverage leaked user information. 7. If immediate patching is not feasible, consider applying compensating controls such as restricting access to the management interface to trusted IP ranges and using VPNs with strong authentication.