OPC UA Deep Dive: A Complete Guide to the OPC UA Attack Surface

Executive Summary 

• OPC UA is the standard unified communication protocol in industrial environments

• Proprietary field devices and ICS/SCADA systems that previously could not exchange data on the OT network now do so over OPC UA, which is now supported by dozens of vendors across industries

• Team82 has compiled a comprehensive guide to OPC UA, examining its history, security features, and attack surface

• Part 1, OPC UA Uncovered: History of the OPC UA Protocol is available today

• In the coming weeks, we will publish additional installations of this guide, including disclosures of new vulnerabilities, details on some of the tools we use—including an OPC UA network fuzzer, and an exploitation framework

OPC UA (Open Protocol Communication Unified Architecture) is today the standard protocol for unified communications in industrial environments. As more vendors build new products that implement OPC UA—or retrofit older devices to support the protocol—it becomes one of the few mutually understood and adopted technologies in OT. 

OPC UA solved critical interoperability issues between field devices and ICS/SCADA systems that previously could not exchange data. Developed by the OPC Foundation, OPC UA is the standard protocol over which engineers and operators can, from a single server, communicate with and manage physical processes on the OT network. The fact that OPC UA is platform independent allows devices from different vendors to seamlessly communicate. 

To achieve this goal, a few components were introduced: the OPC server, OPC client, and the OPC gateway. The OPC server contains many protocol converters that are capable of communicating with devices, such as PLCs, using their proprietary protocols, including Modbus, EtherNet/IP, S7, and more. The OPC server will constantly query devices for specific predefined memory values that are known as tags or points, and store them in a special database. Later, an OPC client, such as an HMI, can communicate with the server using the generic OPC protocol to get the values of these tags/points. 

Team82 has invested considerable time and resources to research the security of the OPC UA protocol. Since 2020, we’ve disclosed more than two dozen vulnerabilities in OPC UA products, or in the protocol stack itself. We’ve researched clients, servers, and other software that supports OPC UA, and our work has helped improve the security of the overall network protocol stack. In addition, we also made freely available a network fuzzer used to find a number of zero-day vulnerabilities in OPC UA products in preparation for the Pwn2Own Miami competition in 2022 and 2023. 

Today, we’re publishing the first in a multipart series of blogs that we hope will be the ultimate resource for OT engineers, asset operators, and asset owners intimately involved in OT network security, and specifically, OPC UA. 

Throughout the series we plan to share our research into the OPC UA attack surface, and provide extensive background on the following:

• The inner workings of the protocol

• Recap OPC UA history

• Explain OPC UA’s security features

• Cover the OPC-UA attack surface

• Disclose some information about new vulnerabilities

• Describe new attack techniques targeting OPC UA

• Introduce a new OPC UA exploit framework and fuzzers. 

Our goal is to publish and maintain a useful OPC UA security guide, one that can be referenced often in order to minimize the risk to OT networks, and reduce the potential for damaging remote code execution or denial-of-service attacks.

OPC UA Deep Dive series

Part 1: History of the OPC UA protocol

In part one of Team82’s series examining the OPC protocol, we look at its history and the different flavors of OPC that have been developed throughout the past two decades. This blog sets the table for the remainder of this series, which will examine the OPC attack surface, security features in the protocol, and attack vectors.
Part 1: History of the OPC UA protocol

Part 2: What is OPC UA?

Part two begins our exploration of the OPC UA protocol, how it's used, its data model, and encoding. This is an extensive technical dive under the hood of the protocol, which is the standardized, secure, and reliable communication channel for exchanging data between devices, machines, and control systems, irrespective of the manufacturer or platform.
Part 2: What is OPC UA?

Part 3: Exploring the OPC UA Protocol

In part three, we cover not only OPC UA's structure, but four messaging types: HEL, OPN, MSG, and CLO, and demonstrated how they come into play while communicating over OPC UA and creating new sessions. Finally, OPC UA’s security features are dissected. Its features enable users to be fully authenticated, authorized, and sign and/or encrypt traffic if they so choose.
Part 3: Exploring the OPC UA Protocol

Part 4: Targeting Core OPC UA Components

In this part, we describe the risk of changing values via OPC UA and the threat associated with exploiting OPC-UA components like servers or gateways. We also delve into the supply chain of OPC-UA components including core libraries, protocols stacks, SDKs and products that are built on top of it.
Part 4: Targeting Core OPC UA Components

Part 5: Inside Team82's Research Methodology

In part five, we explain our research methodology, how we set up our research environment, utilized fuzzers, and dove into the specification to find bugs and vulnerabilities in common protocol implementations. We will also discuss our results including the vulnerabilities we found, and the open-source tools we developed to uncover those issues.
Part 5: Inside Team82's Research Methodology

Part 6: A One-of-a-Kind OPC UA Exploit Framework

The centerpiece tool of our research is an advanced OPC UA Exploit Framework we built and used to execute many unique attacks against OPC UA implementations. It’s been immensely useful in finding close to 50 vulnerabilities in products using the protocol from OPC-UA client to servers to protocol gateways. In part six, we make it publicly available on our GitHub repository, and invite fellow researchers and vendors to use this framework to test their code bases and the security of your respective products.
Part 6: A One-of-a-Kind OPC UA Exploit Framework

Part 7: Practical Denial-of-Service Attacks

Denial of service (DoS) attacks on industrial networks utilizing OPC UA are particularly perilous due to their potential to disrupt critical operations. OPC UA-based systems play a vital role in industrial automation, and a DoS attack can overload network resources or flood communication channels, rendering the system unavailable. In part seven, we explore three attack concepts that could disrupt automation services over OPC UA.

Part 7: Practical Denial-of-Service Attacks

Part 8: Gaining Client-Side Remote Code Execution

We showcase our approach to researching and exploiting OPC UA client applications, where we combined classic OPC UA and OT knowledge with run-of-the-mill web vulnerabilities to uncover zero days in both clients. During our Pwn2Own research journey, we managed to find similar vulnerable code patterns in both applications, exploiting the OPC UA client’s trust in the data it receives from the OPC UA server.

Part 8: Gaining Client-Side Remote Code Execution

Part 9: Targeting OPC UA Integration Servers

We uncovered four new vulnerabilities during our research of the Softing Secure Integration Server, which we were able to chain along with a fifth vulnerability found by the Zero Day Initiative in order to achieve full remote code execution on the server. The vulnerabilities range from bypasses of security features and programming limitations meant to restrict access to the server, to others that allowed us to read and write arbitrary files on the server. 

Part 9: Chaining Vulnerabilities to Exploit Softing OPC UA Integration Servers