Operational Technology (OT) environments — like factories, power plants, distribution centers, and office complexes — are facing increasing risks of cyber attacks. These systems were once isolated from corporate IT networks, but that’s no longer the case.
As organizations adopt more IoT devices and connect OT systems to broader networks, the traditional air gap between OT and IT disappears. This shift increases exposure to threats that were once limited to corporate IT.
A successful attack on OT systems can cause power outages, chemical explosions, and other significant risks to employees and public safety. Potential loss of life is just one reason why investing in OT security is so important. OT systems also drive the critical infrastructure that the modern world relies upon, including electrical distribution, oil & gas, or transportation. Attacks on these types of systems can cause our society to come to halt.
Forward-thinking organizations are securing their OT systems with network segmentation and advanced public key infrastructure (PKI) solutions.
PKI for IoT and OT Security
As OT systems become more connected with modern IT networks, the lines between OT and IT are blurring. The result? Greater efficiencies, real-time monitoring, and data-driven automation.
Which should be great, right?
Except, modern OT environments rely on legacy hardware and proprietary protocols, which typically have sub-par security, that’s if they have any. Legacy systems are usually decades old, lack encryption, and offer minimal to no authentication controls, making them a vulnerability hotbed in a world of evolving threats.
In the Industrial Internet of Things (IIoT) space, X.509 certificates are used in two main ways: to identify devices (Device ID) and to secure operations (operational certificates). Device ID certificates are primarily handled by product managers and factory teams during manufacturing and integration. Operational certificates, which are used for securing device communications and authenticating access, are managed by IT administrators who step into the OT environment.
This use of X.509 certificates ties directly into PKI, which provides the framework for issuing, managing, and validating these certificates.
In the OT security context, for instance, PKI ensures that both devices and their communications are authenticated and encrypted, reducing the risk of spoofing or unauthorized access.
By assigning Device ID certificates to connected products during manufacturing and provisioning, trust is established early in the device lifecycle. Operational certificates then extend that trust into real-time operations, and are managed by the operators to ensure these smart devices aren’t an entry point into the network.
Network Segmentation
Network segmentation is about traffic control. It prevents threat actors from moving laterally from the compromised IoT assets to other parts of the network, essentially limiting the overall attack surface an attacker can exploit. Segmentation creates a more proactive posture that gives your environment layered network security.
Here’s how it works:
Step 1: Isolate Critical Systems
If an IoT sensor, third-party maintenance laptop, or other entry point is compromised, network segmentation limits the ability of an attacker to move freely across networks to reach the most valuable or sensitive systems.
However, in modern OT environments, traditional segmentation alone won’t cut it. You’d have to go deeper, into microsegmentation.
Step 2: Microsegmentation
Microsegmentation is a further step. It allows organizations to define access policies at the workload or device level rather than relying on broad network zones.
When you combine microsegmentation with strict identity-based controls, you move closer to a true Zero Trust architecture; where every request — whether from a user, device, or system — is verified before access is granted. Nothing is assumed safe.
Step 3: Combine with PKI-based authentication
But identity-based access control in OT security only works if you can confidently verify an identity. That’s where PKI-based authentication comes in.
PKI-based authentication is a way to verify digital identities using cryptographic certificates instead of IP addresses or hostnames. Every device is compelled to present a valid certificate before it can talk to other systems. In OT security, this helps ensure that only trusted users or devices can access sensitive systems.
Without a PKI solution, risks reliance on insecure alternatives — like shared passwords, default credentials, or unencrypted protocols. Attackers know this. They exploit those weaknesses to move laterally between systems.
A managed PKI enforces authentication at each network boundary. When combined with segmentation, it only allows authorized devices to access specific zones — and for only approved tasks.
Moreover, enforcing least-privilege access is easier when PKI and segmentation work together. Locking down each segment based on role, device type, or even the age of a certificate limits security breach risks.
PKI + Visibility = Maximum OT Security
Segmentation works best with visibility of the organization’s certificate inventory, including insights about how and where certificates are being used. A lack of visibility increases risks of having expired or defective certificates. With the explosion of certificates in use, it isn’t practical to manage these certificates manually.
In the event of a breach or intrusion, understanding the details of all of the certificates accelerates detection and containment.
Therefore, successful OT security requires automation and oversight to track certificate usage, mapping, and anomaly monitoring This help you quickly revoke the certificate and isolate the affected segment when something looks off.
Build Resilience Now For Secure OT Systems
Building long-term resilience begins by conducting a full cryptographic discovery across your OT and IT environments to help identify unmanaged keys and certificates.
Next, segment your industrial networks using firewalls, VLANs, and identity-aware proxies. Replace password-based access with device certificates to ensure only verified devices can communicate across segments.
Since industrial systems have long life cycles, investing in crypto-agility helps you adapt as cryptographic standards evolve, which in turn helps you tighten your OS security stance.
To maintain visibility & control of your digital assets, use automated certificate lifecycle management tools like Keyfactor Command. This tool helps you manage issuance, renewal, and revocation at scale — even across legacy OT and modern IoT devices. Manual tracking simply cannot keep up with the volume or speed required in today’s environments.
Combining segmentation with strong PKI gives you a layered defense. If a breach occurs, the impact is isolated, and the most critical systems remain protected. PKI-based identity ensures trust, while segmentation limits exposure.
