It is often said that if World War III breaks out, it will be fought in cyberspace. As IoT brings more and more systems together under the umbrella of network connectivity, security has never been more important. From the electrical grid system that powers our world, to the lights that control the flow of traffic in a city, to the systems that keep airplanes flying in an organized and efficient way, security of the networks, devices, and the applications that use them is foundational and essential for all modern communications systems. Providing security in such a world is not easy. Security is among the very few, if not the only, technology disciplines that must operate with external forces continually working against desired outcomes. To further complicate matters, these external forces are able to leverage traditional technology as well as nontechnical methods (for example, physical security, operational processes, and so on) to meet their goals. With so many potential attack vectors, information and cybersecurity is a challenging, but engaging, topic that is of critical importance to technology vendors, enterprises, and service providers alike.
Information technology (IT) environments have faced active attacks and information security threats for many decades, and the incidents and lessons learned are well-known and documented. By contrast, operational technology (OT) environments were traditionally kept in silos and had only limited connection to other networks. Thus, the history of cyber attacks on OT systems is much shorter and has far fewer incidents documented. Therefore, the learning opportunities and the body of cataloged incidents with their corresponding mitigations are not as rich as in the IT world. Security in the OT world also addresses a wider scope than in the IT world. For example, in OT, the word security is almost synonymous with safety. In fact, many of the industrial security standards that form the foundation for industrial IoT security also incorporate equipment and personnel safety recommendations.
It is for these reasons that this chapter focuses on the core principles of securing OT environments. IT security is a vast domain with many books dedicated to its various aspects. An exhaustive treatment of the subject is simply not possible in one chapter, so we instead focus on OT security and the elements of IT security that are fundamental to OT security. In addition, the industry-specific chapters in Part III, “IoT in Industry,” discuss the application of security to specific industry verticals.
This chapter provides a historical perspective of OT security, how it has evolved, and some of the common challenges it faces. It also details some of the key differences between securing IT and OT environments. Finally, this chapter explores a number of practical steps for creating a more secure industrial environment, including best practices in introducing modern IT network security into legacy industrial environments. It includes the following sections:
A Brief History of OT Security: This section provides an overview of how OT environments have evolved and the impact that the evolution has had on securing operational networks.
Common Challenges in OT Security: This section provides a synopsis of different security challenges in operational environments, including legacy systems and insecure protocols and assets.
How IT and OT Security Practices and Systems Vary: This section provides a comparison between the security practices in enterprise IT environments and operational industrial environments.
Formal Risk Analysis Structures: OCTAVE and FAIR: This section provides a holistic view of securing an operational environment and a risk assessment framework that includes the people, processes, and vendor ecosystem components that make up a control system.
The Phased Application of Security in an Operational Environment: This section provides a description of a phased approach to introducing modern network security into largely preexisting legacy industrial networks.
A Brief History of OT Security
To better understand the current situation in industrial environments, it is important to differentiate between assumptions and realities. Few topics in information technology inspire more fear, uncertainty, or doubt than cybersecurity. This chapter is therefore limited to incidents and data sources from official sources rather than public media reports or uncorroborated third-party accounts.
More than in most other sectors, cybersecurity incidents in industrial environments can result in physical consequences that can cause threats to human lives as well as damage to equipment, infrastructure, and the environment. While there are certainly traditional IT-related security threats in industrial environments, it is the physical manifestations and impacts of the OT security incidents that capture media attention and elicit broad-based public concern.
One example of a reported incident where physical damage was caused by a cybersecurity attack is the Stuxnet malware that damaged uranium enrichment systems in Iran. Another example is an event that damaged a furnace in a German smelter. In both incidents, multiple steps led to the undesirable outcomes. Many of the security policies and mitigation procedures that were in place went unheeded; however, if properly implemented, they could have impeded or possibly stopped the attacks entirely. For example, Stuxnet is thought to have been deployed on USB memory sticks up to two years before it was finally identified and discovered.
In addition to physical damage, operational interruptions have occurred in OT environments due to cybersecurity incidents. For example, in 2000, the sewage control system of Maroochy Shire in Queensland, Australia, was accessed remotely, and it released 800,000 liters of sewage into the surrounding waterways. In 2015, the control systems of the Ukrainian power distribution operator Kyiv Oblenergo were remotely accessed by attackers, causing an outage that lasted several hours and resulted in days of degraded service for thousands of customers. In both cases, known mitigation techniques could have been applied to detect the attacks earlier or block the ability to hijack production systems and affect service.
Historically, attackers were skilled individuals with deep knowledge of technology and the systems they were attacking. However, as technology has advanced, tools have been created to make attacks much easier to carry out. To further complicate matters, these tools have become more broadly available and more easily obtainable. Compounding this problem, many of the legacy protocols used in IoT environments are many decades old, and there was no thought of security when they were first developed. This means that attackers with limited or no technical capabilities now have the potential to launch cyber attacks, greatly increasing the frequency of attacks and the overall threat to end operators. It is, however, a common misconception that attackers always have the advantage and that end operators lack effective defensive capabilities. An important advantage for operators is the fact that they are far more familiar with their environment and have a better understanding of their processes, and can thus leverage multiple technologies and capabilities to defend their networks against attack. This is critical as networks will continue to face ever-evolving and changing methods of attack that will be increasingly difficult to defend against and respond to.
Communication networks, both local and geographically dispersed, have been used in industrial environments for decades. For example, remote monitoring of substations in utilities and communications between semi-autonomous systems in manufacturing are long-standing examples of such OT networks. These OT-specific communication systems have typically been standalone and physically isolated from the traditional IT enterprise networks in the same companies. While it follows the traditional logic of “security through obscurity,” this form of network compartmentalization has led to the independent evolution of IT and OT networks, with interconnections between the environments strictly segregated and monitored.
The isolation between industrial networks and the traditional IT business networks has been referred to as an “air gap,” suggesting that there are no links between the two. While there are clearly examples of such extreme isolation in some industries, it is actually not an accurate description of most IoT networks today. Broadly speaking, there is a varying amount of interconnection between OT and IT network environments, and many interdependencies between the two influence the level of interconnection.
In addition to the policies, regulations, and governance imposed by the different industrial environments, there is also a certain amount of end-user preference and deployment-specific design that determines the degree of isolation between IT and OT environments. While some organizations continue to maintain strict separation, others are starting to allow certain elements of interconnection. One common example of this is the use of Ethernet and IP to transport control systems in industrial environments. As much as IT and OT networks are still operated and managed separately in a good portion of the world, the prevailing trend is to consolidate networks based on IT-centric technologies such as TCP/IP, Ethernet, and common APIs.
This evolution of ever-increasing IT technologies in the OT space comes with the benefits of increased accessibility and a larger base of skilled operators than with the nonstandard and proprietary communication methods in traditional industrial environments. The challenges associated with these well-known IT standards is that security vulnerabilities are more widely known, and abuse of those systems is often easier and occurs on a much larger scale. This accessibility and scale makes security a major concern, particularly because many systems and devices in the operational domain were never envisioned to run on a shared, open standards–based infrastructure, and they were not designed and developed with high levels of built-in security capabilities.
Projects in industrial environments are often capital intensive, with an expected life span that can be measured in decades. Unlike in IT-based enterprises, OT-deployed solutions commonly have no reason to change as they are designed to meet specific (and often single-use) functions, and have no requirements or incentives to be upgraded. A huge focus and priority in OT is system uptime and high availability, so changes are typically only made to fix faults or introduce new system capabilities in support of that goal. As a result, deployed OT systems often have slower development and upgrade cycles and can quickly become out of sync with traditional IT network environments. The outcome is that both OT technologies and the knowledge of those looking after those operational systems have progressed at a slower pace than their IT counterparts.
Most of the industrial control systems deployed today, their components, and the limited associated security elements were designed when adherence to published and open standards were rare. The proprietary nature of these systems meant that threats from the outside world were unlikely to occur and were rarely addressed. There has, however, been a growing trend whereby OT system vulnerabilities have been exposed and reported. This increase is depicted in Figure 8-1, which shows the history of vulnerability disclosures in industrial control systems (ICSs) since 2010. While the number of reports has been increasing over the past years, it is likely that there are still many others that are not reported or discovered.
Figure 8-1 History of Vulnerability Disclosures in Industrial Control Systems Since 2010 (US Industrial Control Systems Cyber Emergency Response Team (ICS-CERT) https://ics-cert.us-cert.gov).
Given the slow rate of change and extended upgrade cycles of most OT environments, the investment in security for industrial communication and compute technologies has historically lagged behind the investment in securing traditional IT enterprise environments.