What is a cyber physical system?
A cyber physical system (CPS) is one system that tightly integrates computation with physical processes. In other words, it’s where the digital world meets the physical one. These systems monitor, control, and interact with real-world physical elements like machines and sensors. Cyber physical systems are all around us – like modern vehicles with automatic braking or medical devices that monitor and adjust treatment in real time.
Because CPS are often found in critical sectors – like healthcare, energy, transportation, and manufacturing – they play a vital role in daily life and national infrastructure. This also means they are high-value targets for cyber threats. With regard to AI, the United States National Science Foundation states: “The integration of artificial intelligence with CPS, especially for real-time operation, creates new research opportunities with major societal implications."
Key components of CPS
To understand how cyber physical systems function (and how they can be protected), it's helpful to break them down into their core components:
- Sensors gather data from the physical world – temperature, speed, pressure, motion, etc. – and convert it into digital signals that the system can process. They’re the “eyes and ears” of a CPS.
- Actuators take commands from the system and cause physical movement or changes – like adjusting a valve, steering a vehicle, or changing a machine’s speed. If sensors are the senses, actuators are the hands.
Embedded systems/controllers are the “brains” of the operation. Embedded computers run the software that processes sensor data, makes decisions, and sends commands to actuators. Often built for specific tasks, they must be both reliable and secure.
Networks and communication systems enable CPS components to talk to each other – often in real time. Communication systems enable data exchange between sensors, controllers, actuators, and sometimes external systems. Cybersecurity here is essential, since a compromised communication channel can lead to serious disruptions.
Human-machine interface (HMI) is how people interact with CPS, whether through dashboards, control panels, or mobile apps. A secure and intuitive interface helps operators monitor system status and intervene when needed.
Together, these elements make CPS intelligent, responsive, and interconnected – but also introduce multiple points where vulnerabilities can arise.
Why CPS security matters
Cyber physical systems aren’t just high-tech curiosities – they’re foundational to how modern industries and infrastructures function. From keeping the lights on to ensuring safe travel, CPS powers much of the critical services we rely on every day.
Real-world impact of cyberattacks
Unlike traditional IT systems, where a breach might lead to data theft or service outages, attacks on CPS can cause physical harm. Imagine a hacked water treatment plant releasing unsafe water, a compromised vehicle braking system causing an accident, or a threat actor deploying malware and ultimately disabling emergency equipment in a hospital.
Because CPS controls real-world processes, a successful cyberattack can lead to injury, environmental damage, infrastructure failures, or worse. That elevated risk makes security in CPS not just a matter of business continuity but of public safety.
Growing interconnectivity increases exposure
As industries embrace digital transformation, CPS are becoming more connected – to each other, to enterprise networks, and even to the internet. While this connectivity brings efficiency and innovation, it also expands the attack surface.
Increased connectivity means that a vulnerability in one part of the system – like a misconfigured remote access point – can become a gateway for attackers to move laterally into critical operations. Securing CPS requires a deep understanding of both cyber and physical domains as well as proactive defenses to reduce risk across this increasingly interconnected landscape.
Common CPS security threats and vulnerabilities
Just like traditional IT systems, cyber physical systems face a wide range of security risks – but with a unique twist: These risks can cross the boundary from the digital world into the physical. To effectively secure CPS, it’s important to understand both the threats and the vulnerabilities.
Common CPS security threats
- Nation-state actors backed by governments may target CPS in critical infrastructure or defense for espionage, disruption, or sabotage. These attacks are often stealthy, well-resourced, and highly tailored to specific systems.
- Cybercriminals and ransomware groups target CPS environments with ransomware or extortion schemes, especially in sectors like manufacturing and healthcare where downtime can be dangerous.
- Insider threats – like employees, contractors, or others with legitimate access – can intentionally or unintentionally compromise CPS. Whether it's negligence, lack of training, or malicious intent, insiders are uniquely positioned to bypass many security controls.
- Hacktivists and terrorists are ideologically motivated attackers who may seek to disrupt or damage CPS to make a political statement or cause harm. These groups may exploit known vulnerabilities in widely deployed systems.
- Unintentional threats are, in fact, not malicious. Misconfigured devices, outdated firmware, or human mistakes can open the door to security incidents or cause critical failures.
Common CPS vulnerabilities
- Legacy systems and outdated software are the bedrock on which CPS systems are built. They were never designed with modern security in mind. These systems often lack basic protections like data encryption or authentication.
- Weak or default credentials are sometimes default settings in devices and control systems. Surprisingly, these credentials are rarely changed. Attackers know this and often scan for such easy targets.
- Unsecured communication channels could leave vulnerable data traveling between sensors, controllers, and actuators, allowing attackers to intercept or manipulate information in transit.
- Lack of network segmentation is critical for securing physical systems. If CPS networks are connected directly to enterprise IT networks – or even the internet – without proper segmentation, attackers can pivot from less secure systems into critical operational areas.
- Inadequate monitoring and log management affects visibility into what’s happening across the system. Thus, it can be hard to detect intrusions or suspicious behavior. Many CPS environments lack the tools or resources for effective monitoring.
- Physical access risks are inherent to CPS systems, as they include physical components in the real world. For this reason, attackers may be able to physically tamper with or access devices – especially in remote or poorly secured environments.
How CPS differs from traditional IT systems
While cyber physical systems may include some familiar technologies – like networks, software, and operating systems – they're fundamentally different from traditional IT systems in several important ways.
Physical consequences of failures
In traditional IT systems, failures typically affect digital assets – lost data, inaccessible files, or interrupted services. In CPS, failures can lead to physical harm, such as damaged equipment, environmental hazards, or threats to human safety.
For example, a software glitch in an office email server might cause a temporary communication hiccup. A similar glitch in a factory’s robotic arm controller could halt production or injure a worker.
Real-time and deterministic requirements
CPS often operates under strict timing and performance constraints. They must respond to inputs and events in real time. Many CPS are designed with deterministic behavior in mind, meaning actions must be predictable and repeatable, without delays or variability.
This is very different from traditional IT environments, where a few seconds of lag in loading a webpage isn’t a big deal. In a CPS, even minor delays can lead to incorrect responses or unsafe conditions, so security controls must not interfere with time-sensitive operations.
Long lifespans and limited updatability
CPS are frequently deployed in environments where systems are expected to run reliably for years or even decades, such as industrial plants, energy grids, or transportation infrastructure. Unlike consumer IT systems that receive regular updates, many CPS are difficult – or risky – to update once in place.
This makes patch management a major challenge. Security solutions must often work within the constraints of legacy hardware, unsupported software, and update cycles measured in years, not weeks.
CPS vs. IoT: Similarities and key differences
It’s easy to confuse CPS and Internet of Things (IoT) devices, and while they do share some overlap, they’re not the same. IoT devices typically focus on connectivity and convenience – think smart thermostats or fitness trackers. They collect data and may allow remote control, but they often operate independently or in loosely coupled networks.
CPS, on the other hand, are tightly integrated systems where sensing, computation, and actuation work together in real time to control physical processes. In short:
- IoT is often about data and user experience.
- CPS is about control, coordination, and safety in real-world environments.
Recognizing these differences is key when applying security frameworks – what works for securing a smartphone app won’t necessarily cut it for a medical robot or a smart turbine.
CPS security in critical infrastructure
Critical infrastructure systems control everything from electricity distribution to emergency medical equipment. When they work, most people never notice them. But when they fail – especially due to a cyberattack – the results can be far-reaching and severe.
Key challenges in securing CPS within critical infrastructure
Securing CPS in critical infrastructure environments is no small task. These systems face unique technical and operational challenges that make traditional cybersecurity solutions difficult to apply directly. Let’s break down some of the most pressing obstacles.
Limited ability to patch or update
Many critical infrastructure systems are built to last decades and were never designed with frequent software updates in mind. For example, a control system in a power substation may be running on proprietary software that hasn’t been updated in years – because applying a patch might require taking the system offline and disrupting a key service.
Convergence of IT and OT networks
Traditionally, operational technology (OT) – the hardware and software used to monitor and control physical processes – was isolated from IT networks. Digital transformation is changing that, with OT systems increasingly connected to IT infrastructure for monitoring, analytics, and remote access.
While this convergence brings efficiency and visibility, it also introduces new attack pathways, which highlight the need for OT security. An attacker might compromise a corporate email system and pivot into the OT network that controls a railway’s signaling system. Without strict segmentation and access controls, the door between business operations and critical physical processes can swing wide open.
Operational uptime requirements
Many critical infrastructure systems are expected to run 24/7, with little to no downtime. This creates an environment where security changes are hard to implement without affecting essential services. For instance, taking down part of the electrical grid for a security audit could mean blackouts.
Geographic and physical security gaps
Infrastructure like pipelines, pumping stations, or rail networks often spans large, remote areas. Devices may be physically exposed, making them vulnerable not just to cyber threats, but to physical tampering or sabotage – especially if security policies focus only on digital risks.
Securing CPS in critical infrastructure requires tailored strategies that balance safety, uptime, and cybersecurity. It’s not just about protecting systems – it’s about protecting the real-world functions those systems enable.
Best practices for securing CPS environments
Securing cyber physical systems isn’t about applying one-size-fits-all solutions – it requires a layered, thoughtful approach that considers both the cyber and physical sides of the system. Because CPS are often safety-critical, connected to legacy infrastructure, and designed for continuous operation, security must be built in carefully and strategically.
Network segmentation and access control
One of the most effective ways to limit the spread of attacks is through network segmentation – separating IT and OT networks and restricting traffic between them. This helps contain threats and prevents attackers from moving laterally.
Use strong access control policies, such as role-based access control (RBAC), to ensure users and devices only have access to what they need – and nothing more. Apply the principle of least privilege access (LPA) wherever possible.
Regular risk assessments and threat modeling
CPS environments are complex and interconnected, so it’s important to routinely conduct risk assessments to identify weak points, high-value assets, and potential threat vectors. Pair this with threat modeling to anticipate how different types of attackers might target your system, and what impact those attacks could have on safety and operations.
Secure configuration and hardening
Many CPS devices come with insecure default settings – open ports, unused services, default credentials – that can be exploited. Hardening devices means disabling unnecessary functions, changing default passwords, and applying configuration baselines that reduce attack surfaces.
Monitoring, logging, and anomaly detection
Visibility is key. Implement continuous monitoring and centralized logging to keep an eye on device activity, network traffic, and user behavior. Because many CPS environments can’t tolerate downtime, detecting suspicious behavior early is essential to stopping attacks before they cause damage.
Consider deploying anomaly detection systems that are trained to recognize the expected behavior of physical processes – and alert operators when something deviates from the norm.
Patching and update planning (when possible)
While it may not always be feasible to apply patches immediately in a CPS environment, organizations should still maintain an update strategy. This includes tracking vulnerabilities in deployed systems, coordinating with vendors, and scheduling patch windows during low-risk periods.
Physical security measures
Don’t forget the physical side of CPS. Secure field devices, control rooms, and access points with physical protections like locks, fences, surveillance, and badge-controlled entry. Many attacks can start with physical tampering or unauthorized access – especially in remote infrastructure.
Employee training and incident response planning
Human error remains a top risk in CPS environments. Provide security awareness training to staff and contractors, with a focus on secure operations, social engineering awareness, and proper procedures for accessing systems.
Just as important, have a tested incident response plan in place that includes procedures specific to CPS – like isolating affected components without disrupting safe physical operations.