Identity-driven OT segmentation is replacing static firewall controls

At a glance

What this is: This is a Corsha infographic arguing that OT segmentation is moving from static network controls to identity-driven verification for machine communication.

Why it matters: It matters because OT and IAM teams now have to govern machine access as an identity problem across legacy and modern systems, not only as a network-path problem.

👉 Read Corsha's infographic on modernising OT segmentation and access

Context

OT segmentation is the practice of limiting which systems can talk to each other, but the control model matters as much as the boundary itself. In environments where production systems, industrial networks, robotics, edge systems, and cloud platforms are now interconnected, static firewall rules and manual policy changes become slow to adapt and easy to drift out of alignment with actual machine communication patterns.

For identity and access teams, the real issue is machine-to-machine trust. When access is tied to IP addresses and network paths alone, the programme cannot express who a workload is, what it is allowed to do, or whether that communication should still be valid in the current operational state. That is why machine identity and workload identity controls are becoming part of OT governance rather than an optional add-on.

Key questions

Q: What breaks when OT segmentation depends on static network rules?

A: Static OT segmentation breaks when network location is no longer a reliable proxy for trust. As environments add cloud connectivity, robotics, edge systems, and modern applications, IP-based rules and manual policy changes become brittle, create hidden trust paths, and leave lateral movement opportunities that are hard to detect or audit.

Q: Why does machine identity matter more in connected OT environments?

A: Machine identity matters because OT access decisions increasingly need to answer who or what is communicating, not just where the traffic came from. When production systems and cloud-connected tools share infrastructure, identity-based verification gives security teams a durable way to govern machine-to-machine trust across changing topologies.

Q: How do teams know if OT segmentation is still working?

A: OT segmentation is working only if access decisions remain accurate when systems move, scale, or connect to new platforms. If the programme depends on frequent manual rule edits, exceptions, or subnet assumptions to keep traffic flowing, the control is already drifting away from the operational reality it is meant to protect.

Q: Who should own identity-driven access decisions in OT?

A: Ownership should be shared across OT security, IAM, and platform teams because machine communication policy spans network behaviour, identity assurance, and operational uptime. If those decisions sit only with network teams, identity governance is usually too weak to handle modern machine-to-machine access safely.

Technical breakdown

Why static OT segmentation breaks down in connected environments

Traditional OT segmentation was designed for relatively fixed networks where policy could be expressed once and enforced for long periods. In modern environments, topology changes, cloud connectivity, and hybrid applications create too much movement for static firewall rules, VLANs, and IP-based allowlists to stay accurate. The control fails when the boundary no longer reflects the actual identity of the communicating machine. That creates brittle policy, manual exceptions, and hidden trust paths that are difficult to audit.

Practical implication: teams should treat network segmentation as a supporting control, not the primary trust decision for machine communication.

What identity-driven machine-to-machine verification changes

Identity-driven access controls verify the communicating machine before the connection is permitted, rather than trusting the network location alone. In operational environments, that means the policy decision can incorporate machine identity, workload context, and connection intent. The benefit is not just tighter control, but a policy model that can adapt without redesigning the network every time a system moves or a new dependency is introduced. This is especially relevant where OT systems must coexist with modern applications and cloud-connected tooling.

Practical implication: build policy around machine identity assertions and connection approval, then map legacy network rules to that model incrementally.

How zero trust principles apply to OT machine access

Zero Trust in OT is not about removing segmentation, it is about refusing implicit trust in the path itself. Each machine-to-machine connection should be verified continuously, with access decisions based on identity and expected behaviour rather than the assumption that anything inside the network is safe. This reduces lateral movement opportunities and makes policy management more sustainable as the environment grows. It also aligns OT governance more closely with identity security practice used elsewhere in the enterprise.

Practical implication: use identity-first verification to reduce implicit trust and limit lateral movement across operational systems.

Threat narrative

Attacker objective: The objective is to move laterally through OT-connected systems by exploiting trust that is defined by network position instead of verified identity.

1. Entry occurs when an attacker or rogue machine reaches an operational segment that is protected mainly by static network rules.
2. Escalation follows when lateral movement is possible because access is inferred from network location rather than verified machine identity.
3. Impact occurs when the attacker uses the weak trust model to move between operational systems and disrupt production or reach sensitive control paths.

Breaches seen in the wild

• Schneider Electric credentials breach — exposed credentials gave attackers access to Schneider Electric Jira, exfiltrating 40GB.
• Cisco DevHub NHI breach — IntelBroker exploited exposed Cisco credentials, API tokens and keys in DevHub.

Read our 52 NHI Breaches Analysis report for a comprehensive view of breaches impacting Non-Human Identities including AI Agents.

NHI Mgmt Group analysis

Static OT segmentation is now an assumption problem, not just a control problem. The old model assumes that network location is a reliable proxy for trust, but that assumption fails when production, robotics, edge, and cloud systems all exchange traffic dynamically. Corsha's framing shows why OT security can no longer rely on firewall shape alone. Practitioners should treat identity as the trust primitive for machine communication.

Machine identity turns OT access into a governance issue. Once machine-to-machine traffic spans legacy and modern systems, access is no longer only about permitted paths. It becomes about whether the communicating workload is known, authenticated, and expected in that context. That shifts responsibility toward IAM, OT security, and platform teams working from a shared control model. Practitioners should align segmentation policy with identity lifecycle and workload governance.

Zero Trust in OT only works when it can speak to machines, not just networks. The article reinforces a broader industry direction: zero trust principles are becoming operationally relevant for industrial environments because implicit trust creates lateral movement risk. The real test is whether a policy can verify the machine before communication is allowed and still preserve production stability. Practitioners should judge zero trust controls by whether they reduce operational risk without forcing constant network redesign.

Industrial Identity Security is a useful named concept because it captures the shift from path control to connection control. That concept matters because OT teams are not merely segmenting networks anymore, they are defining which machine identities may communicate under what conditions. The implication is that policy management, auditability, and resilience all move closer to identity governance. Practitioners should adopt identity-driven language when they brief OT and security stakeholders.

From our research:

• 88.5% of organisations acknowledge that their non-human IAM practices lag behind or are merely on par with their human identity and access management efforts, according to The 2024 Non-Human Identity Security Report.
• 59.8% of organisations see value in a solution that simplifies non-human access management and introduces dynamic ephemeral credentials, according to The 2024 Non-Human Identity Security Report.
• For a broader control baseline, see Ultimate Guide to NHIs for the lifecycle, visibility, and rotation issues that make machine access hard to govern.

What this signals

Industrial Identity Security: OT teams are moving toward a model where machine communication is verified as an identity event, not presumed from topology. That matters because static network segmentation cannot keep pace with cloud-connected production environments, and the governance burden shifts from rule maintenance to identity assurance.

The maturity gap is already visible across the wider non-human estate. According to The 2024 Non-Human Identity Security Report, 35.6% of organisations cite managing consistent access across hybrid and multi-cloud environments as their top NHI security challenge, which is the same underlying problem OT teams now face as industrial connectivity expands.

For practitioners, the forward signal is clear: OT segmentation, machine identity, and zero trust are converging into a single operating model. Teams that only modernise the network layer will still leave trust decisions too implicit, so the next step is to connect operational access policy to identity lifecycle and verification controls.

For practitioners

• Map machine communication to identity, not just subnet Inventory the systems that exchange OT traffic and document which connections are currently allowed only because they share a network segment or IP range. Replace those implicit assumptions with explicit machine identity and connection policy where possible.
• Review static firewall and VLAN dependencies Identify where segmentation still depends on manual policy updates, brittle allowlists, or fixed topology assumptions. Prioritise the connections that would create the largest lateral movement risk if those controls drift.
• Introduce continuous verification for machine-to-machine access Require a verification step before communication is allowed, especially for connections that bridge legacy OT systems and modern applications. Use the result to reduce trust in the network path itself.
• Align OT segmentation with identity lifecycle governance Define ownership, onboarding, and offboarding for machine identities so access does not outlive the system or workload that needs it. Make lifecycle review part of the change process for new OT connections.

Key takeaways

• Static OT segmentation is losing effectiveness because network position no longer reliably represents machine trust.
• Identity-driven verification shifts OT access from path control to connection control, which better matches modern hybrid operations.
• Teams should align segmentation, machine identity, and lifecycle governance so trust does not depend on brittle manual firewall maintenance.

Key terms

• Machine Identity: A machine identity is the credentialed representation of a workload, device, service, or system used to prove who it is before it communicates. In OT and hybrid environments, machine identity gives security teams a way to govern access independently of network location or IP address.
• Identity-Driven Segmentation: Identity-driven segmentation is a control model that allows or denies communication based on verified identity rather than only on subnet, firewall, or VLAN placement. It is especially useful in operational environments where topology changes frequently and network paths no longer describe trust accurately.
• Zero Trust For Machines: Zero trust for machines applies the never trust, always verify principle to workload and device communication. It requires each connection to be checked against identity and policy before access is granted, which helps reduce lateral movement in connected industrial and hybrid systems.
• Operational Technology: Operational technology is the hardware and software used to monitor and control physical processes such as manufacturing, robotics, utilities, and industrial automation. Its security requirements differ from IT because uptime, safety, and change control can limit how quickly controls may be updated.

Deepen your knowledge

NHI governance, agentic AI identity, and machine identity lifecycle are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If you are responsible for identity security strategy or NHI governance in your organisation, it is worth exploring.

This post draws on content published by Corsha: INFOGRAPHIC: Modernize OT Segmentation and Access. Read the original.