Siemens RADIUS Client of SIPROTEC 5 Devices

As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global).

1. EXECUTIVE SUMMARY CVSS v3 7.5 ATTENTION: Exploitable remotely/low attack complexity Vendor: Siemens ProductCERT Equipment: RADIUS client of SIPROTEC 5 devices Vulnerability: Loop with Unreachable Exit Condition (‘Infinite Loop’)
2. RISK EVALUATION The RADIUS client implementation of the VxWorks platform in SIPROTEC 5 devices contains a denial-of-service vulnerability that could be triggered when a specially crafted packet is sent by a RADIUS server.
3. TECHNICAL DETAILS 3.1 AFFECTED PRODUCTS The following software from Siemens is affected: SIPROTEC 5 6MD85 (CP300) - >= V7.80 = V7.80 = V7.80 SIPROTEC 5 6MU85 (CP300) - >= V7.90 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V8.81 = V9.20 = V8.30 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V7.80 = V8.70 3.2 VULNERABILITY OVERVIEW 3.2.1 LOOP WITH UNREACHABLE EXIT CONDITION (‘INFINITE LOOP’) CWE-835 An issue was discovered in Wind River VxWorks 6.9 and 7 that allows a specifically crafted packet sent by a RADIUS server, which could cause a denial-of-service condition during the IP Radius access procedure. CVE-2022-38767 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). 3.3 BACKGROUND CRITICAL INFRASTRUCTURE SECTORS: Energy COUNTRIES/AREAS DEPLOYED: Worldwide COMPANY HEADQUARTERS LOCATION: Germany 3.4 RESEARCHER Siemens reported this vulnerability to CISA.
4. MITIGATIONS Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk: SIPROTEC 5 6MD85 (CP300): Update to V9.30 or later version SIPROTEC 5 6MD86 (CP300): Update to V9.30 or later version SIPROTEC 5 6MD89 (CP300): Currently no fix is planned SIPROTEC 5 6MU85 (CP300): Update to V9.30 or later version SIPROTEC 5 7KE85 (CP300): Update to V9.30 or later version SIPROTEC 5 7SA86 (CP300): Update to V9.30 or later version SIPROTEC 5 7SA87 (CP300): Update to V9.30 or later version SIPROTEC 5 7SD86 (CP300): Update to V9.30 or later version SIPROTEC 5 7SD87 (CP300): Update to V9.30 or later version SIPROTEC 5 7SJ85 (CP300): Update to V9.30 or later version SIPROTEC 5 7SJ86 (CP300): Update to V9.30 or later version SIPROTEC 5 7SK85 (CP300): Update to V9.30 or later version SIPROTEC 5 7SL86 (CP300): Update to V9.30 or later version SIPROTEC 5 7SL87 (CP300): Update to V9.30 or later version SIPROTEC 5 7SS85 (CP300): Update to V9.30 or later version SIPROTEC 5 7ST85 (CP300): Update to V9.30 or later version SIPROTEC 5 7ST86 (CP300): Update to V9.30 or later version SIPROTEC 5 7SX85 (CP300): Update to V9.30 or later version SIPROTEC 5 7UM85 (CP300): Update to V9.30 or later version SIPROTEC 5 7UT85 (CP300): Update to V9.30 or later version SIPROTEC 5 7UT86 (CP300): Update to V9.30 or later version SIPROTEC 5 7UT87 (CP300): Update to V9.30 or later version SIPROTEC 5 7VE85 (CP300): Update to V9.30 or later version SIPROTEC 5 7VK87 (CP300): Update to V9.30 or later version SIPROTEC 5 Communication Module ETH-BA-2EL: Update to V9.30 or later version SIPROTEC 5 Communication Module ETH-BB-2FO: Update to V9.30 or later version SIPROTEC 5 Communication Module ETH-BD-2FO: Update to V9.30 or later version SIPROTEC 5 Compact 7SX800 (CP050): Update to V9.30 or later version Protect the pre-shared key for RADIUS from unauthorized access Ensure that only a trusted, properly hardened RADIUS server is configured in your environment Operators of critical power systems (e.g. TSOs or DSOs) worldwide are usually required by regulations to build resilience into the power grids by applying multi-level redundant secondary protection schemes. It is therefore recommended that the operators check whether appropriate resilient protection measures are in place. The risk of cyber incidents impacting the grid’s reliability can thus be minimized by virtue of the grid design.
   Siemens strongly recommends applying the provided security updates using the corresponding tooling and documented procedures made available with the product. If supported by the product, an automated means to apply the security updates across multiple product instances may be used. Siemens strongly recommends prior validation of any security update before being applied, and supervision by trained staff of the update process in the target environment. As a general security measure
   Siemens strongly recommends users protect network access with appropriate mechanisms (e.g. firewalls, segmentation, VPNs). It is advised to configure the environment according to our operational guidelines to run the devices in a protected IT environment. Recommended security guidelines can be found at the Siemens webpage for grid security. For further inquiries on security vulnerabilities in Siemens products and solutions, users should contact the Siemens ProductCERT.
   For more information, see the associated Siemens security advisory SSA-726834 in HTML and CSAF. CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should: Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the Internet. Locate control system networks and remote devices behind firewalls and isolate them from business networks. When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its connected devices. CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures. CISA also provides a section for control systems security recommended practices on the ICS webpage at cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies. Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents. CISA also recommends users take the following measures to protect themselves from social engineering attacks: Do not click web links or open attachments in unsolicited email messages. Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams. Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks. No known public exploits specifically target this vulnerability.