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Advisory (ICSA-18-226-02)

Siemens OpenSSL Vulnerability in Industrial Products (Update A)

Original release date: August 14, 2018 | Last revised: September 11, 2018

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  • CVSS v3 5.9
  • ATTENTION: Exploitable remotely
  • Vendor: Siemens
  • Equipment: Industrial Products
  • Vulnerability: Cleartext Transmission of Sensitive Information


This updated advisory is a follow-up to the original advisory titled ICSA-18-226-02 Siemens OpenSSL Vulnerability in Industrial Products that was published August 14, 2018, on the NCCIC/ICS-CERT website.


Successful exploitation of this vulnerability could result in unencrypted data being transmitted by the SSL/TLS record layer.



Siemens reports that the vulnerability affects the following industrial products: 

  • MindConnect IoT2040: All versions prior to v03.01, 
  • MindConnect Nano (IPC227D): All versions prior to v03.01, 
  • SIMATIC ET 200SP Open Controller CPU 1515SP PC (OC1): All versions prior to v2.1, 
  • SIMATIC HMI WinCC Flexible: All versions, 
  • SIMATIC IPC DiagBase: All versions, 
  • SIMATIC IPC DiagMonitor: All versions, 
  • SIMATIC S7-1200: All versions, 
  • SIMATIC S7-1500: All versions prior to v2.5.2, 
  • SIMATIC S7-1500 Software Controller: All versions, 
  • SIMATIC STEP 7 (TIA Portal): All versions prior to v15 Update 2,
  • SIMATIC WinCC (TIA Portal): All versions prior to v15 Update 2, 
  • SIMATIC WinCC OA v3.14: All versions, 
  • SIMATIC WinCC OA v3.15: All versions, 
  • SIMATIC WinCC OA v3.16: All versions, 
  • SINUMERIK Integrate Access MyMachine service engineer client as part of Sinumerik Integrate Product suite: All versions prior to and including v4.1.7, and 
  • SINUMERIK Integrate Operate Client as part of Sinumerik Integrate Product suite: All versions prior to and including v2.0.11 / v3.0.11



In OpenSSL 1.0.2 an “error state” mechanism was introduced. This “error state” mechanism does not work correctly if SSL_read() or SSL_write() is called directly by an application. This could result in data being sent out unencrypted by the SSL/TLS record layer.

Successful exploitation requires an attacker to cause a fatal error in the targeted SSL/TLS handshake algorithm, and that the targeted application calls SSL_read() or SSL_write() only after receiving the fatal error. No user interaction or privileges are required to exploit this security vulnerability. The vulnerability could allow a compromise of data confidentiality by transmitting it unencrypted over the network. 

CVE-2017-3737 has been assigned to this vulnerability. A CVSS v3 base score of 5.9 has been assigned; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N).


  • CRITICAL INFRASTRUCTURE SECTORS: Chemical, Critical Manufacturing, Energy, Food and Agriculture, Water and Wastewater Systems


Siemens reported this vulnerability to NCCIC.


Siemens has provided updates for the following products to fix the vulnerability:

  • MindConnect IoT2040: Install v03.01 or newer via Mindsphere web front-end
  • MindConnect Nano (IPC227D): Install v03.01 or newer via Mindsphere web front-end
  • SIMATIC S7-1500: Update to v2.5.2


SIMATIC STEP 7 and WinCC (TIA Portal): Update to v15 Update 2 or newer


--------- Begin Update A Part 1 of 1 --------
  • SIMATIC WinCC OA V3.14: Update to v3.14-P021
  • SIMATIC WinCC OA V3.15: Update to v3.15-P014
  • SIMATIC WinCC OA V3.16: Update to v3.16-P002

https://portal.etm.at/index.php?option=com_ content&view=category&id=67&layout=blog& Itemid=80

--------- End Update A Part 1 of 1 --------
  • SINUMERIK Integrate Access MyMachine service engineer client as part of Sinumerik Integrate Product suite: Update to v4.1.8
  • SINUMERIK Integrate Operate Client as part of Sinumerik Integrate Product suite: Update to v2.0.12 / v3.0.12

Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:

  • S7-1200: Disable web server within the device configuration if it is not used, or limit access to the web server on a particular Ethernet/PROFINET port/interface if possible (setting is under General /Web server access).

As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens’ operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security), following the recommendations in the product manuals.

Additional information on Industrial Security by Siemens can be found at:

For more information on this vulnerability and associated software updates, please see Siemens security advisory SSA-179516 on their website:


NCCIC 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 that they are not accessible from the Internet.
  • Locate control system networks and remote devices behind firewalls, and isolate them from the business network.
  • When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing that VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize that VPN is only as secure as the connected devices.

NCCIC reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

NCCIC also provides a section for control systems security recommended practices on the ICS-CERT web page. Several recommended 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-CERT website in the Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to NCCIC for tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability. High skill level is needed to exploit.

Contact Information

For any questions related to this report, please contact the NCCIC at:

Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  http://ics-cert.us-cert.gov 
or incident reporting:  https://ics-cert.us-cert.gov/Report-Incident?

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