ICS Advisory (ICSA-21-168-02)

Softing OPC-UA C++ SDK

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1. EXECUTIVE SUMMARY

  • CVSS v3 7.5
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Softing
  • Equipment: OPC-UA C++ SDK
  • Vulnerability: Improper Restriction of Operations within the Bounds of a Memory Buffer

2. RISK EVALUATION

A remote attacker may be able to crash the device, resulting in a denial-of-service condition. This vulnerability exists in exported functions of the library, and exploits may have different consequences depending on how the library functions have been used.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Softing reports the vulnerability affects functions in the following software library, which may be used in other products: 

  • OPC UA C++ SDK (Software Development Kit) Versions from 5.59 to 5.64

3.2 VULNERABILITY OVERVIEW

3.2.1    IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER CWE-119

The exported library functions don't properly validate received extension objects, which may allow an attacker to crash the software by sending a variety of specially crafted packets to access several unexpected memory locations. 

CVE-2021-32994 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Multiple sectors
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Eran Jacob of OTORIO reported this vulnerability to CISA.

4. MITIGATIONS

Softing has released version 5.65 to address this vulnerability and has notified known users of the release. As this vulnerability only affects the publisher and subscriber protocol, Softing highly recommends customers using this protocol to upgrade to the latest version or disable the functionality. Please download the latest software package from the Softing website

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

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