CVE-2024-38867 identifies a cryptographic weakness (CWE-326) in Siemens SIPROTEC 5 series devices, including numerous models such as 6MD84, 6MD85, 7SA82, 7SJ81, 7SL82, 7UT82, and others, as well as associated communication modules (ETH-BA-2EL, ETH-BB-2FO, ETH-BD-2FO). The vulnerability arises from the use of weak encryption ciphers on several TCP ports: port 443 (HTTPS web interface), port 4443 (DIGSI 5 configuration software), and configurable ports used for syslog over TLS. These weak ciphers do not provide adequate cryptographic strength, enabling an attacker positioned in a man-in-the-middle (MitM) role to decrypt intercepted traffic. This could expose sensitive operational data, configuration details, or credentials transmitted between management consoles and the devices. The vulnerability affects all versions prior to 9.64 (or 9.65/8.90 depending on model) and is present across a broad range of SIPROTEC 5 devices widely used in electrical grid protection and automation. The CVSS v3.1 score is 5.9 (medium), reflecting network attack vector, high confidentiality impact, but no impact on integrity or availability, and requiring high attack complexity without privileges or user interaction. No known exploits are currently reported in the wild. Siemens has published advisories identifying affected versions but no direct patch links are provided in the data. The vulnerability underscores the importance of strong cryptographic standards in industrial control systems (ICS) to prevent data leakage and potential reconnaissance by threat actors.

For European organizations, particularly those in the energy sector operating Siemens SIPROTEC 5 devices for grid protection and automation, this vulnerability poses a significant confidentiality risk. An attacker capable of intercepting network traffic—such as through compromised network segments or insider threats—could decrypt sensitive operational data, potentially revealing grid configurations, control commands, or credentials. This exposure could facilitate further targeted attacks, including disruption or manipulation of critical infrastructure. While the vulnerability does not directly impact system integrity or availability, the leakage of sensitive information can undermine operational security and resilience. Given the strategic importance of energy infrastructure in Europe and the widespread deployment of Siemens SIPROTEC devices, this vulnerability could be leveraged in espionage or sabotage campaigns. Additionally, regulatory frameworks like NIS2 and GDPR emphasize protecting critical infrastructure and personal data, so exploitation could have compliance and reputational consequences. The medium severity rating suggests a moderate but non-trivial risk that requires timely mitigation to prevent escalation.

1. Upgrade all affected Siemens SIPROTEC 5 devices and communication modules to the latest firmware versions (9.64 or later as applicable) where weak cipher support has been removed or strengthened. 2. Review and disable weak or deprecated cryptographic ciphers and protocols on all exposed ports (443, 4443, and syslog TLS ports) via device configuration settings or network controls. 3. Implement network segmentation and strict access controls to limit exposure of SIPROTEC devices to trusted management networks only, reducing the risk of MitM attacks. 4. Employ network monitoring and intrusion detection systems to detect anomalous traffic patterns indicative of MitM or interception attempts. 5. Use VPNs or encrypted tunnels with strong cryptography for remote access to SIPROTEC devices to add an additional layer of protection. 6. Conduct regular security audits and penetration tests focusing on cryptographic configurations of ICS devices. 7. Train operational technology (OT) personnel on the risks of weak encryption and the importance of applying security updates promptly. 8. Coordinate with Siemens support for guidance on secure configuration and any available patches or mitigations. 9. Maintain an inventory of all affected devices to ensure comprehensive coverage of updates and mitigations. 10. Consider compensating controls such as physical security enhancements and strict network device authentication to reduce attack surface.