ICS Advisory (ICSA-17-173-01)

Siemens SIMATIC CP 44x-1 Redundant Network Access Modules

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CVSS v3 9.8

ATTENTION: Remotely exploitable/low skill level to exploit.

Vendor: Siemens

Equipment: SIMATIC CP 44x-1 Redundant Network Access (RNA) modules

Vulnerability: Improper Authentication


The following versions of the SIMATIC CP 44x-1 RNA, which connect SIMATIC S7-400 CPUs to Industrial Ethernet, are affected:

  • SIMATIC CP 44x-1 RNA, all versions prior to Versions 1.4.1.


Successful exploitation of this vulnerability may allow an unauthenticated remote attacker to perform administrative actions under certain conditions.


Siemens has released firmware update, Version 1.4.1, for the SIMATIC CP 44x-1 RNA modules that fixes the vulnerability and is available at the following location:


Siemens recommends that users apply the firmware update.

Siemens recommends that users apply the following mitigations until the firmware update can be applied:

  • Apply cell protection concept, described in the following:


  • Use VPN for protecting network communication between cells
  • Apply Defense-in-Depth, which is described in the following:


NCCIC/ICS-CERT recommends that 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.

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.

No known public exploits specifically target this vulnerability.


An unauthenticated remote attacker may be able to perform administrative actions on the Communication Process (CP) of the RNA series module, if network access to Port 102/TCP is available and the configuration file for the CP is stored on the RNA’s CPU.

CVE-2017-6868 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).


Siemens reported this vulnerability.


Critical Infrastructure Sector(s): Chemical, Critical Manufacturing, and Food and Agriculture

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Munich, Germany

Contact Information

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

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  https://us-cert.cisa.gov/ics 
or incident reporting:  https://us-cert.cisa.gov/report

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