The Fence or the Force Field? Top 5 Benefits of Segmenting Your OT Network

If you’re managing an Operational Technology (OT) network, whether it’s a factory floor, a utility grid, or a processing plant, you live by one rule: availability comes first. For too long, this mandate has been the reason to postpone critical security upgrades, leaving many industrial networks dangerously flat and interconnected.

But the reality of modern threats (especially hyper-aggressive ransomware) means that a flat network is now an unacceptable risk. When one device is compromised, the attacker has a free pass to scan and attack every other critical asset. The recent announcement of how Chinese hackers used Claude is another warning sign: AI-powered attacks are here, and if they gain access to your network, they will run rampant.

The solution is segmentation. But as we’ll see, not all segmentation is created equal. Let’s dive into the top five benefits you gain when you ditch the flat network and implement layered defenses.

1. Stop Lateral Movement Dead in Its Tracks

This is the number one reason to segment your network. Lateral movement is what happens after an attacker gains their initial foothold (via a phishing email on an engineering workstation or an infected USB stick). They move "laterally" across the network, escalating privileges, mapping assets, and finally finding the crucial PLC or SCADA system they want to destroy or encrypt.

• Segmentation (Traditional): Separates the network into large zones (e.g., the corporate IT network, the DMZ, and the entire production floor) using firewalls and VLANs. If an attacker gains access to the production zone, they still have a vast, flat playground to operate in.
• Microsegmentation (Now): This is the game-changer. It defines access down to the individual asset level, creating a secure connection only between two trusted endpoints (e.g., the HMI and the specific PLC it controls). This is why a Zero Trust approach is so powerful.

BlastWave Insight: Microsegmentation, built on a Zero Trust architecture, enforces Network Cloaking. If an unauthorized device tries to scan a protected asset, it receives no response, the asset is simply invisible. This stops lateral movement not by detecting it, but by making reconnaissance and attack paths impossible.

2. Dramatically Reduce Your Attack Surface and Scope

When your entire plant is in one zone, a vulnerability in a low-priority asset (such as a security camera or an unattended printer) instantly becomes a vulnerability for your most critical Level 0 controls. Segmentation reduces the scope of a breach.

• Segmentation (Traditional): By separating IT from OT, you limit an IT-based attack (like a broad malware infection) from reaching the control systems. The scope is now the smaller OT network.
• Microsegmentation (Now): By defining least-privilege access for every asset, you ensure that if one component is compromised, the blast radius is reduced to that single device. A successful attacker gains a beachhead on a single HMI, but they cannot use that HMI to talk to the neighboring database or PLC unless explicitly authorized. This drastically reduces the cost and time required for recovery.

3. Enhance Compliance and Improve Auditability

Industrial operators in critical sectors (energy, water, etc.) face increasingly stringent regulatory requirements (like NERC-CIP in North America). Segmentation is almost universally a mandated control, but microsegmentation provides the high-fidelity evidence regulators demand.

• Segmentation (Traditional): Provides network boundaries necessary to satisfy baseline compliance requirements for "network separation."
• Microsegmentation (Now): Directly enforces Least Privilege Access (LPA) based on identity (who the person is) and device posture (what device they are using). This granular control generates detailed, definitive logs showing who accessed what and when. This level of detailed auditability moves you from simply "checking the box" to providing irrefutable proof of control, which is essential for audits and forensic investigations.

4. Enable Faster, More Effective Incident Response

In the event of a successful attack, the first twenty minutes are critical. If your network is flat, responders are scrambling to determine which assets are communicating and which ones to unplug physically. If your network is segmented, containment becomes surgical.

• Segmentation (Traditional): If an infected machine is detected in a specific subnet, the security team can quickly block all traffic to and from that entire subnet at the boundary firewall, containing the threat to a limited operational zone while other zones remain running.
• Microsegmentation (Now): Since access is based on identity and policy, the response is often automated and instant. You don't block a subnet; you simply revoke the compromised user’s credentials or the device’s certificate in the central policy engine. Since the connection relies on an authenticated identity, the moment the identity is revoked, the connection is instantly severed, and access to all protected assets is lost.

5. Secure Legacy and Agentless Critical Assets

Many OT networks avoid segmentation because they fear disrupting legacy PLCs or remote terminal units (RTUs) that cannot run security agents or handle complex firewall traffic.

• Segmentation (Traditional): Requires physically re-cabling, re-IPing, and inserting complex, latency-introducing hardware in front of the legacy asset, which poses a significant risk to availability.
• Microsegmentation (BlastWave's Approach): This is where solutions explicitly built for OT shine. By deploying a small, hardened Gateway device on the same segment as the legacy asset, the Gateway acts as a Zero Trust shield. It cloaks the asset's IP and intercepts all traffic, only allowing authenticated and authorized access.

BlastWave Insight: The BlastWave Gateway protects the legacy device without touching the device itself. No code changes, no reboots, no downtime. You get full security and invisibility for your 20-year-old PLC by simply adding the protective Gateway next to it, preserving the OT mandate of availability while fulfilling the security mandate of segmentation.

Segmentation is no longer a luxury. While basic segmentation provides necessary perimeter defense, the true power lies in microsegmentation, which stops the spread of threats from the inside. And it isn’t as hard as you fear. 

Are you ready to move beyond the fear of network changes and implement surgical security that guarantees uptime? Attend our webinar to learn how.

‍

— Cam Cullen, CMO, Blastwave