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TLP:WHITE

Advisory (ICSA-17-243-03)

Siemens 7KM PAC Switched Ethernet

Original release date: August 31, 2017 | Last revised: September 11, 2017

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CVSS v3 4.3

ATTENTION: Low skill level to exploit.

Vendor: Siemens

Equipment: 7KM PAC Switched Ethernet

Vulnerability: Resource Exhaustion

AFFECTED PRODUCTS

Siemens reports that the vulnerability affects the following 7KM PAC Switched Ethernet PROFINET expansion modules:

  • 7KM PAC Switched Ethernet PROFINET expansion module: All versions prior to V2.1.3

IMPACT

Successful exploitation of this vulnerability could cause a denial-of-service condition in the affected component that may require a manual restart of the main device to recover.

MITIGATION

Siemens provides firmware Version V2.1.3 for 7KM PAC Switched Ethernet PROFINET expansion modules, which fixes the vulnerability, and recommends users to update to the new fixed version. The new firmware update can be found at the following location:

https://support.industry.siemens.com/cs/ww/en/view/109749555

Siemens recommends users protect network access with appropriate mechanisms such as firewalls, segmentation, and VPNs. Siemens also advises that users configure the operational environment according to Siemens’ Operational Guidelines for Industrial Security:

https://www.siemens.com/cert/operational-guidelines-industrial-security

For more information on this vulnerability and more detailed mitigation instructions, please see Siemens Security Advisory SSA-771218 at the following location:

http://www.siemens.com/cert/advisories

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. This vulnerability is not remotely exploitable.

VULNERABILITY OVERVIEW

A denial-of-service condition could be induced by a specially crafted PROFINET DCP packet sent as a local Ethernet (Layer 2) broadcast. The affected component requires a manual restart via the main device to recover.

CVE-2017-9945 has been assigned to this vulnerability. A CVSS v3 base score of 4.3 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

RESEARCHER

Siemens reported this vulnerability and released an advisory with firmware update information.

BACKGROUND

Critical Infrastructure Sectors: Energy

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Germany


Contact Information

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

Email: NCCICCUSTOMERSERVICE@hq.dhs.gov
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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