For years, industrial cybersecurity has focused on protecting the plant perimeter: firewalls, antivirus software, physical access controls, and hardening of PLCs, SCADA systems, and HMIs. The assumption was simple: keep attackers out and the operation stays safe.

But the most recent data tells a different story. The main risk to OT environments does not come from outside. It originates within the organization itself, and more specifically, from the convergence between IT and OT networks that most industrial companies have not properly secured.

What the Data Actually Shows

According to the TXOne Networks 2024 Annual OT/ICS Cybersecurity Report, 98% of cybersecurity incidents in OT environments originate in IT systems. In 68% of those cases, the attack crosses directly into the OT network. These are not edge cases or theoretical scenarios. They represent the dominant pattern of how industrial infrastructure gets compromised today.

The implication is direct: if IT/OT convergence is not properly designed and segmented, it becomes the single greatest operational risk vector in modern industrial environments.

Why Corporate Security Is Not Enough for OT Protection

Many industrial companies already have perimeter firewalls, corporate antivirus solutions, and IT security policies in place. The problem is that these measures were designed for IT environments and do not translate directly into OT protection.

In practice, IT and OT systems in many plants share networks without real segmentation, reused credentials, shared servers for historians and remote access, overly permissive firewall rules, and poorly controlled maintenance access points. Under these conditions, an apparently minor IT incident, whether phishing, ransomware, or a set of compromised credentials, can spread into OT without ever needing to directly compromise an industrial device.

The consequences go beyond a security incident. A breach that reaches OT systems is a direct risk to operational continuity, physical safety, and product quality.

The Flat Network Model No Longer Works

The flat network model that most OT environments inherited from an era when plant systems were completely isolated is no longer viable. Industrial digitalization, advanced analytics, and artificial intelligence all require data exchange between plant systems and corporate infrastructure. That connectivity is necessary. But connectivity does not have to mean exposure.

Standards like IEC 62443 and NIST SP 800-82 are clear on this point: network segmentation is the foundation of OT cybersecurity. Knowing where the IT domain ends and where the OT domain begins is not an organizational decision. It is an architectural one, and it needs to be treated as such from the earliest stages of network design.

IT and OT Security Are Not the Same Problem

One of the most common and costly mistakes in industrial cybersecurity is applying IT security models directly to OT environments. In IT, the primary concern is confidentiality. In OT, the priorities are availability and physical safety, and the tolerance for disruption is far lower.

An aggressive network scan, a misapplied patch, or an unexpected outage caused by a security tool can halt production within seconds. This is why IT/OT separation is not just a policy recommendation. It is a structural requirement that has to be embedded in how networks are designed, not added as an afterthought.

How Artificial Intelligence Changes the OT Security Equation

AI is already present in many industrial plants, powering predictive maintenance, computer vision systems, anomaly detection, and process optimization. Like digitalization more broadly, AI amplifies both the strengths and the weaknesses of the underlying architecture.

In an IT/OT environment without proper segmentation, AI systems introduce new risk. They require access to OT data to deliver value, which means they can become entry points or lateral movement pathways if the architecture around them is not secure.

The same OT cybersecurity principles that apply to traditional industrial systems apply equally to industrial AI: strict segmentation between IT, OT, and AI services, unidirectional or tightly controlled data channels, full visibility of traffic generated by AI models, and clear update and hardening policies for AI components. Without this approach, AI increases complexity and expands the attack surface rather than reducing risk.

The Real Starting Point for OT Cybersecurity

As long as IT and OT continue to share infrastructure without effective architectural separation, the risk will grow alongside every new digital initiative. The lesson from current incident data is consistent: in modern industrial environments, cybersecurity does not start at the firewall. It starts in the network design.