ICS Advisory (ICSA-16-327-02A)

Siemens SIMATIC CP 343-1/CP 443-1 Modules and SIMATIC S7-300/S7-400 CPUs Vulnerabilities (Update A)

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This updated advisory is a follow-up to the original advisory titled ICSA-16-327-02 Siemens SIMATIC CP 343-1CP 443-1 Modules and SIMATIC S7-300S7-400 CPUs Vulnerabilities that was published November 22, 2016, on the NCCIC/ICS-CERT web site.

Siemens has released an advisory regarding vulnerabilities affecting SIMATIC CP 343-1 Advanced/CP-443-1 Advanced devices and SIMATIC S7-300/S7-400 CPUs. Inverse Path auditors and the Airbus ICT Industrial Security team reported these vulnerabilities directly to Siemens. Siemens has made new firmware versions available for several products and a temporary fix for the remaining affected products to mitigate these vulnerabilities.

These vulnerabilities could be exploited remotely.


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Siemens reports that the vulnerabilities affect the following SIMATIC products:

  • SIMATIC CP 343-1 Advanced: All versions prior to V3.0.53,
  • SIMATIC CP 443-1 Advanced: All versions prior to V3.2.17,
  • SIMATIC S7-300 CPU family: All firmware versions, and
  • SIMATIC S7-400 CPU family: All firmware versions.

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Under certain conditions, an attacker could use these vulnerabilities to perform operations as an authenticated user.

Impact to individual organizations depends on many factors that are unique to each organization. ICS-CERT recommends that organizations evaluate the impact of these vulnerabilities based on their operational environment, architecture, and product implementation.


Siemens is a multinational company headquartered in Munich, Germany.

Communication Processor (CP) modules SIMATIC CP 343-1 Advanced and CP 443-1 Advanced are designed to enable SIMATIC S7-300/S7-400 CPUs to communicate via Ethernet.

According to Siemens, several critical infrastructure (CI) sectors deploy these products, including Chemical, Critical Manufacturing, and Food and Agriculture. Siemens estimates that users of these products are located worldwide.




The integrated web server at Port 80/TCP or Port 443/TCP of the affected devices could allow remote attackers to perform actions with the permissions of an authenticated user, provided the targeted user has an active session and is induced to trigger the malicious request.

CVE-2016-8673b has been assigned to this vulnerability. A CVSS v3 base score of 6.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L).c


The integrated web server delivers cookies without the “secure” flag. Modern browsers interpreting the flag would mitigate potential data leakage in case of clear text transmission.

CVE-2016-8672e has been assigned to this vulnerability. A CVSS v3 base score of 4.0 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N).f



These vulnerabilities could be exploited remotely.


No known public exploits specifically target these vulnerabilities.


An attacker with a low skill may be able to exploit these vulnerabilities.


Siemens provides firmware versions that fix the vulnerabilities and recommends that users update to the fixed versions:

  • SIMATIC CP 343-1 Advanced: Update to V3.0.53:


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  • SIMATIC CP 443-1 Advanced: Update to V3.2.17:


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For SIMATIC S7-300/S7-400 CPUs, Siemens recommends the following mitigations:

  • Apply cell protection concept,
  • Use VPN for protecting network communication between cells, and
  • Apply Defense-in-Depth.

Siemens strongly recommends users protect network access to SIMATIC S7-300/S7-400 CPUs and to the web interface of SIMATIC CP 343-1 Advanced and CP 443-1 Advanced devices with appropriate mechanisms. Siemens also advises that users configure the protected operational environment according to Siemens’ Operational Guidelines for Industrial Security:


For more information on this vulnerability and more detailed mitigation instructions, please see Siemens Security Advisory SSA-603476 at the following location:


Siemens will update SSA-603476 and ICS-CERT will update this advisory when new information becomes available.

ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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.

ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

ICS-CERT 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 in the ICS‑CERT Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies, that is available for download from the ICS-CERT web site.

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

  • a. CWE-345: Insufficient Verification of Data Authenticity, https://cwe.mitre.org/data/definitions/345.html, web site last accessed November 22, 2016.
  • b. NVD, https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-8673, web site last accessed March 21, 2017.
  • c. CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L, web site last accessed November 22, 2016.
  • d. CWE-614: Sensitive Cookie in HTTPS Session Without 'Secure' Attribute, https://cwe.mitre.org/data/definitions/614.html, web site last accessed November 22, 2016.
  • e. NVD, https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-8672, web site last accessed March 21, 2017.
  • f. CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N, web site last accessed November 22, 2016.

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