Why Network Segmentation Matters

Network segmentation is a cornerstone of OT cybersecurity. It involves dividing a network into isolated, secure zones—either physically or virtually—each acting as a self-contained subnetwork. This approach:

• Reduces risk
• Enhances control
• Prevents lateral movement in the event of a breach

The Cybersecurity and Infrastructure Security Agency (CISA) emphasizes the importance of segmentation and provides a clear, actionable framework for its implementation—especially for critical infrastructure environments.

Top 5 Benefits of Network Segmentation

1. Threat Containment: Compromised systems are confined within their segment, preventing wider disruption.
2. Smaller Attack Surface: Limiting inter-zone communication reduces paths for attackers to reach sensitive assets.
3. Protection of Critical Assets: High-value systems like DCSs, PLCs, HMIs, and control servers are isolated from less secure IT zones.
4. Improved Monitoring: Smaller zones allow for more precise anomaly detection and event tracking.
5. Compliance Enablement: Helps meet requirements in frameworks like ISA/IEC 62443, which mandate segmentation as a baseline control.

Key Components of an Effective Segmentation Strategy

1. Define and Group Zones

Organize assets by function and risk level. Typical OT zones include:

• Control Zone: PLCs, DCS, SCADA, most critical layer.
• Historian Zone: Operational data aggregation.
• MES Zone: Operational-to-enterprise handoff.
• Remote Access Zone: For secure third-party or vendor access.
• Enterprise IT Zone: Business apps and office systems.

2. Establish Secure Conduits Between Zones

• Strict Communication Rules: Permit only essential traffic between zones, with defined protocols and endpoints.
• Firewalls with ACLs: Use industrial firewalls and Access Control Lists to strictly manage inter-zone traffic.
• DMZ Deployment: A DMZ acts as a secure proxy zone between IT and OT, preventing direct access while enabling controlled data exchange.

3. Test, Monitor, and Maintain Continuously

• Validate Controls: Post-deployment testing ensures segmentation functions correctly without disrupting operations.
• Continuous Monitoring: Track traffic flows and flag deviations or unauthorized access attempts.
• Ongoing Review: Update policies as new assets or threats arise.

The Champion Advantage

Effective segmentation requires more than IT knowledge, it demands a deep understanding of industrial processes. That’s where Champion Technology Services excels.

We deliver segmentation strategies that:

• Protect operations without disrupting uptime
• Align with CISA guidance and industry specific standards
• Bridge IT security best practices with OT realities

We combine cybersecurity leadership with control system expertise to design and implement resilient, scalable, and compliant network architectures for critical infrastructure environments.

In today's increasingly connected operational environments, network segmentation is a foundational pillar for cybersecurity, performance, and system reliability. For industrial facilities managing legacy assets, segmentation isn't just an IT best practice, it's a business-critical strategy.

What is Network Segmentation?

Network segmentation involves dividing a network into smaller, isolated segments (or subnets), each with its own access controls and security measures. This approach:

• Minimizes the attack surface
• Restricts lateral movement by threat actors
• Prevents malware from spreading across the network

6 Key Strategies for Effective Segmentation

1. IT/OT Alignment

Ensure collaboration between IT and OT teams from the outset. Joint planning, training, and awareness initiatives build shared ownership and improve execution.

2. Identify Critical Assets

Prioritize protection by identifying which systems are most critical to operations. This enables a phased segmentation approach that minimizes disruption.

3. Network Mapping

Visualizing all connected entities reveals data flows, hidden vulnerabilities, and monitoring blind spots—essential for informed segmentation planning.

4. Define Network Zones

Group systems with similar security requirements into zones, and enforce strict rules for how data moves between them. This zoning model forms the backbone of OT segmentation.

5. Implementation

Roll out segmentation in phases to minimize operational risk. Closely monitor performance throughout the rollout to identify and resolve unforeseen issues early.

6. Monitor and Maintain

Ongoing monitoring and regular audits ensure the segmentation strategy adapts to evolving threats. Update protocols and configurations as your network grows or changes.

The Takeaway

As cyber threats grow more sophisticated, network segmentation is no longer optional—it’s foundational. By creating controlled, isolated zones within your OT network, you enhance system protection, simplify compliance, and future-proof your operations for digital transformation.

Is an Air-Gap “Good Enough” to keep your Industrial Control System secure? Short answer: No. Here’s why…

“Security by isolation” or air-gapping previously worked in Operational Technology (OT) environments when OT and IT were completely isolated from one another. Many older systems based on PLC’s and SCADA were built without cybersecurity in mind. OT and IT are now converging as organizations embrace the digital transformation, and security experts are now declaring the air gap dead as security by isolation is not a long-term solution for protecting OT assets.

Air Gapping an OT system has very limited value in today’s constant technological advances. It can no longer be used as a sole security solution in the long term for three reasons:

• It causes organizations to miss out on valuable data.
• It is more costly and difficult for maintenance and repairs.
• It is more prone to security breaches than a “connected” OT system.

Missing out on Data

While air-gapped OT systems can minimize risks, organizations are not able to benefit from the highly valuable data these systems generate. Data analyzed in real time can provide business intelligence to cut costs, reduce downtime, and improve efficiency. These opportunity costs outweigh air-gapping as a viable cyber security measure.

Higher Maintenance Costs

Maintaining air-gapped OT systems are more expensive and difficult because the engineering tools of a connected system cannot be used to perform routine maintenance or troubleshoot problems. It also limits the system from secure remote support by technical experts. Without remote access, facilities experience higher support costs and increased downtime. The reality is that even a properly air-gapped system is not completely protected; Every system is a potential breach target, and even air-gapped systems can be infiltrated. Organizations must engage in active monitoring and security measures to mitigate the risks.

Reduced Security

Air Gaps can be physically breached by a third-party networked laptop, USB drive, removable media, smartphone, or other devices. Allowing OT systems to connect with these devices creates vulnerabilities that air gapping cannot protect against. Air gapping makes it difficult for users to move back and forth between the air-gapped device and network-connected devices. For ease of use, an individual may use an unsecure USB drive to transfer data which could compromise an air-gapped system.

OT infrastructure is only as secure as the user operating the devices. An openly accessible USB port can serve as an entry route for malware. Smartphones provide another convenient route to cross air gaps when switched to Wi-Fi hotspot mode. The Wi-Fi hotspots can also be used as an entry point by hackers or those with ill intentions.

90+% of randomly found USB drives are picked up by the casual person and more than half are plugged into a PC.
Source: Kapersky

Why your OT control systems can’t afford cybersecurity shortcuts:

OT cyber-attacks are more dangerous in nature. An OT attack can pose risks to operational and safety systems, employees, plant, and environment. Because the outcome of an OT cyber-attack is more catastrophic, it is essential that organizations prioritize cybersecurity. While air gapping provides some security, it is not the best option to select in the competitive marketplace.

Air gapped control systems are also more vulnerable because they don’t receive the latest Windows security patches easily, therefore are usually neglected. As new virus threats emerge, the OT system will likely be unprotected, unlike its Enterprise counterpart.

We must accept the fact that air gapping as a security control is no longer a valid option. IT and OT will continue to converge leaving air gapping to be useless. Facilities should take advantage of the opportunities from integrated technologies to reduce costs and downtime while improving efficiency. While doing so, they must prioritize OT security to lessen the risk and still capitalize on the advantages of a connected IT and OT world.