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
- Equipment: SIMATIC and SIPLUS products
- Vulnerabilities: Uncontrolled Recursion, Buffer Access with Incorrect Length Value
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could allow an unauthorized attacker with network access to the web server to perform a denial-of-service attack.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following products of Siemens, are affected:
- SIMATIC S7-400 CPU 412-2 PN V7 (6ES7412-2EK07-0AB0): All versions
- SIMATIC S7-400 CPU 414-3 PN/DP V7 (6ES7414-3EM07-0AB0): All versions
- SIMATIC S7-400 CPU 414F-3 PN/DP V7 (6ES7414-3FM07-0AB0): All versions
- SIMATIC S7-400 CPU 416-3 PN/DP V7 (6ES7416-3ES07-0AB0): All versions
- SIMATIC S7-400 CPU 416F-3 PN/DP V7 (6ES7416-3FS07-0AB0): All versions
- SIMATIC PC-Station Plus: All versions
- SINAMICS S120 (incl. SIPLUS variants): All versions prior to SP3 HF15
- SIPLUS S7-400 CPU 414-3 PN/DP V7 (6AG1414-3EM07-7AB0): All versions
- SIPLUS S7-400 CPU 416-3 PN/DP V7 (6AG1416-3ES07-7AB0): All versions
3.2 Vulnerability Overview
The affected products do not handle HTTP(S) requests to the web server correctly. This could allow an attacker to exhaust system resources and create a denial-of-service condition for the device.
The affected products do not handle long file names correctly. This could allow an attacker to create a buffer overflow and create a denial-of-service condition for the device.
- CRITICAL INFRASTRUCTURE SECTORS: Multiple
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Germany
Siemens reported these vulnerabilities to CISA.
Siemens recommends updating the following products to the latest version where available:
Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:
- Disable the web server of the affected system
- Restrict access to webserver for trusted users only
As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. To operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens’ operational guidelines for industrial security and following recommendations in the product manuals.
Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage.
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, such as:
- Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
- Locate control system networks and remote devices behind firewalls and isolating them from business networks.
- When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs). Recognize VPNs may have vulnerabilities, should be updated to the most recent version available, and are only as secure as the 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 on cisa.gov. 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.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov 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.
No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.
5. UPDATE HISTORY
- December 14, 2023: Initial Publication