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TLP:WHITE

Advisory (ICSA-15-267-01)

Endress+Hauser Fieldcare/CodeWrights HART Comm DTM XML Injection Vulnerability

Original release date: September 24, 2015 | Last revised: August 27, 2018

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OVERVIEW

Alexander Bolshev of Digital Security has identified a vulnerability within Endress+Hauser HART DTM software libraries. The vulnerability is in handling of the HART longtag response field in Endress+Hauser’s Fieldcare and CodeWrights HART Comm DTM.

Endress+Hauser Process Solutions AG and CodeWrights have produced new versions of the software that in combination mitigates the vulnerability. Alexander Bolshev has tested the updated versions to validate that it resolves the vulnerability.

This vulnerability could be exploited from an adjacent network receiving HART DTM packets.

AFFECTED PRODUCTS

All HART DTM components relying on Fieldcare and a CodeWrights HART Comm DTM are impacted. Individual components are not listed within this advisory because of the extreme number of potentially impacted devices.

IMPACT

When a Device DTM component receives a HART packet response to Command 20 (longtag), it extracts the longtag from the packet. The string is capable of storing an XML schema. The HART Comm DTM reads the XML schema and attempts to retrieve XML schema or the document from the location stored in the longtag. This leads to potential Server Side Request Forgery (SSRF) attacks or XML External Entity attacks. This attack may cause the disclosure of confidential data, denial of service, port scanning, and other possible system impacts from the perspective of the machine where the parser is located.

In an SSRF, the network connection will originate from the application server internal IP, and an attacker will be able to use this connection to bypass network controls. This could allow exposure of internal resources that are not otherwise visible.

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

BACKGROUND

Endress+Hauser is an international company based in Germany and Switzerland, with over 200 offices and production centers located worldwide.

CodeWrights GmbH is a German-based company that provides device integration and management solutions. CodeWrights GmbH supplies components that are used in DTMs of other vendors.

The Endress+Hauser Fieldcare manages the FDT/DTM Frame Application. The HART Comm DTM is part of the FDT/DTM architecture used to provide communication protocol information to the Frame Application. ICS-CERT has concluded these devices are deployed across several sectors including Chemical, Commercial Facilities, Critical Manufacturing, Energy, Food and Agriculture, Water and Wastewater Systems, and others. ICS-CERT estimates that these DTMs are used in products worldwide.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

XML CODE INJECTIONa

XML schema is injected into the accepted response packet. When Comm DTM reads longtag values from the Device DTM it attempts to parse the XML schema potentially allowing for remote access and control.

CVE-2015-6463b has been assigned to this vulnerability. A CVSS v3 base score of 8.3 and temporal score of 7.5 has been assigned for each vulnerability; the CVSS vector string is (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:P/RL:O/RC:C).c

VULNERABILITY DETAILS

EXPLOITABILITY

This vulnerability could be exploited from an adjacent network receiving HART DTM packets.

EXISTENCE OF EXPLOIT

No known public exploits specifically target this vulnerability.

DIFFICULTY

An attacker with a low skill would be able to exploit this vulnerability.

MITIGATION

Endress+Hauser and CodeWrights have provided their own security advisories and patches which can be found at:

Endress+Hauser: https://portal.endress.com/webdownload/FieldCareDownloadGui/

CodeWrights: http://www.codewrights.de/index.php/en/downloads/software

Asset owners using FieldCare or CodeWright HART Comm DTMs should update their software to the newest version as soon as possible.

Some processes may require continual configuration changes. ICS-CERT recommends asset owners maintain all software with the latest security releases, limit connections outside the control system, and monitor approved connections for suspicious traffic. ICS-CERT also recommends that asset owners employ a least privilege practice and avoid unnecessary services within their production environment.

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 at: http://ics-cert.us-cert.gov/content/recommended-practices. 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 (http://ics-cert.us-cert.gov/).

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.


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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