Remote access into OT and ICS environments has always carried risk.
But the nature of that risk has changed.
Threat detections now happen in seconds. Sensors identify anomalous behavior in real time. Identity platforms continuously evaluate trust. SIEM and OT security tools generate rich, contextual alerts instantly.
Yet in most environments, access enforcement is still manual. A detection triggers a ticket. A human reviews. A decision is made. Minutes—or hours—pass before action is taken.
In critical infrastructure, that delay is the attack window.
Xona Active Defense closes it.
What Is Active Defense?
Active Defense transforms Xona’s secure remote access platform from static policy enforcement into dynamic, event-driven session control. Rather than waiting for a human to intervene, Xona Gateways now respond automatically to real-time risk signals from OT asset visibility and detection platforms.
The core idea is simple: if your detection stack sees something, your access controls should respond—immediately, proportionally, and without operator intervention.
Risk changes. Access adapts. All at the session layer.
A Bi-Directional Event Loop Between Detection and Enforcement
At the core of Active Defense is a bi-directional event loop between OT detection platforms and the Xona Gateway. Here’s what that loop looks like in practice:
- An OT cyber sensor or Xona SRA Gateway generates a detection event.
- The event is authenticated, verified, and correlated against other signals.
- The Active Defense engine evaluates severity, asset criticality, and user context.
- A response action is executed directly against the live remote session.
- The enforcement result is acknowledged and logged for audit and compliance.
No tickets. No manual playbooks. No exposure gap. Enforcement happens in seconds—not hours.
Session-Layer Enforcement Without Operational Disruption
This is where Active Defense takes a fundamentally different approach from traditional network-level enforcement.
In OT environments, dropping a network tunnel or cutting firewall access can cause cascading disruptions—alarms, lost communications, unsafe states. That’s why Xona operates at the session layer, not the network layer. Instead of bluntly severing connectivity, Active Defense applies precise, proportional controls to the specific remote session at risk:
- Suspend a session into a wait state, pending approvals
- Require immediate MFA reauthentication
- Restrict access to a segmented scope
- Terminate the session outright
- Trigger coordinated alerting across the security stack
The result is graduated enforcement that protects your most critical assets without creating unnecessary operational risk. Security teams get the response they need. Plant operations stay intact.
Correlation That Prevents Overreaction
Alert fatigue is real. Any enforcement system that fires on every single detection event is going to cause more harm than good—especially in environments where uptime is measured in safety, not just SLAs.
Active Defense includes a multi-source correlation model that evaluates patterns before escalating to a higher response tier. Multiple medium-severity detections tied to the same asset or user can automatically elevate enforcement, while isolated low-confidence signals are held until context supports action.
This means:
- Multi-source intelligence informs decisions before action is taken
- False positives are reduced without sacrificing responsiveness
- Escalation is driven by pattern recognition—not panic
Security becomes contextual instead of reactive.
Built for OT Protocol Integrity
Industrial control environments demand deterministic, tamper-resistant behavior. A security system that can itself be spoofed or replayed is no security system at all. Active Defense was designed with this in mind from the ground up.
Every enforcement action is protected by:
- Digitally signed payloads (RSA / Ed25519)
- Mutual TLS with certificate pinning
- Idempotency keys and replay attack protection
- Correlation IDs for full state tracking
- Full audit logging aligned to ISA/IEC 62443 and NERC CIP
No spoofed enforcement actions. No duplicate session terminations. No assumed state changes. Every action is authenticated, verifiable, and compliant.
Active Defense in Action: Remote PLC Firmware Update
Imagine a third-party vendor is remotely updating firmware on a programmable logic controller (PLC) at a water treatment facility. Mid-session, an OT anomaly detection platform identifies suspicious command behavior that doesn’t match the expected update pattern.
With traditional remote access, that alert might sit in a queue while an analyst assesses it. The vendor’s session stays active. Commands keep flowing.
With Active Defense:
- The detection event is securely sent to the Xona Gateway.
- It’s verified, correlated, and evaluated in real time.
- Enforcement logic weighs severity against asset criticality.
- The session is immediately suspended pending reauthentication—or terminated outright if risk is high.
- The OT platform receives confirmation of the action taken.
The attack window shrinks from hours to seconds. The PLC is protected. The plant keeps running.
Who Is Active Defense Built For?
Active Defense is designed for organizations where the stakes of a compromised remote session are too high to tolerate manual enforcement delays:
- Critical infrastructure operators protecting high-value OT assets in energy, utilities, water, and manufacturing
- Security teams integrating OT detection platforms with access governance
- Organizations modernizing away from static VPN or jump-server models
- Environments where uptime, safety, and regulatory compliance are non-negotiable
If your detection stack already operates in real time, your enforcement should too.
Availability and Integrations
Active Defense is available now as part of the Xona secure remote access platform in v5.5. The initial release supports Forescout’s OT sensor integration, with Nozomi and Dragos integrations planned for future releases.
Whether you’re modernizing OT access architecture, reducing mean-time-to-enforce, or closing the gap between detection and response, Active Defense delivers session-aware, automated protection designed specifically for industrial environments
Get Started with Active Defense
New to Xona? Schedule a demo to see Active Defense in action and learn how it integrates with your existing OT detection stack.
Existing Xona customers? Contact your Xona representative to enable Active Defense in your deployment today.
