ICS Advisory (ICSA-21-133-04)

OPC UA Products Built with the .NET Framework 4.5, 4.0, and 3.5

Click to Tweet.
Click to send to Facebook.
Click to Share.

Legal Notice

All information products included in https://us-cert.cisa.gov/ics are provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained within. DHS does not endorse any commercial product or service, referenced in this product or otherwise. Further dissemination of this product is governed by the Traffic Light Protocol (TLP) marking in the header. For more information about TLP, see https://us-cert.cisa.gov/tlp/.


 

1. EXECUTIVE SUMMARY

  • CVSS v3 7.2
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Unified Automation GmbH
  • Equipment: .NET applications
  • Vulnerability: Exposure of Sensitive Information to an Unauthorized Actor

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an unauthenticated attacker to read any file on the file system.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following OPC UA products are affected:

  • Unified Automation .NET based OPC UA Client/Server SDK Bundle: Versions V3.0.7 and prior (.NET 4.5, 4.0, and 3.5 Framework versions only)

3.2 VULNERABILITY OVERVIEW

3.2.1    EXPOSURE OF SENSITIVE INFORMATION TO AN UNAUTHORIZED ACTOR CWE-200

The OPC UA .NET Framework can expose sensitive information to an actor who is not authorized to have access.

CVE-2021-27434 has been assigned to this vulnerability. A CVSS v3 base score of 7.2 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L). 

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Multiple
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: United States

3.4 RESEARCHER

Eran Jacob with the Otorio Research Team reported this vulnerability to CISA.

4. MITIGATIONS

Unified Automation has released software (login required) to address the .NET Framework vulnerabilities. OPC Foundation recommends users deploying OPC UA .NET products built against the .NET 4.5, 4.0, and 3.5 Frameworks should contact the product supplier to determine if an update is needed. Users should also consider upgrading to a version of the product using .NET 4.5.2 Framework or later. It is recommended users avoid using the end-of-life version of the .NET Framework due to the risk of unpatched vulnerabilities.

This vulnerability was originally documented by Microsoft in CVE-2015-6096

CISA 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 VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its connected devices.

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

CISA also provides a section for control systems security recommended practices on the ICS webpage on us-cert.cisa.gov. 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 webpage on us-cert.cisa.gov 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 CISA for tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability.


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

CISA continuously strives to improve its products and services. You can help by choosing one of the links below to provide feedback about this product.

This product is provided subject to this Notification and this Privacy & Use policy.

Please share your thoughts.

We recently updated our anonymous product survey; we'd welcome your feedback.