Securing the Grid:
Zero Trust for Utility Infrastructure

The Legacy Dilemma

Utility infrastructure wasn’t built for modern threats. Legacy PLCs, DCS systems, and OSes - often decades old - are difficult to secure and can’t support modern IAM or encryption standards. Common challenges include:

• Legacy Equipment Constraints: Long-lifecycle devices lack support for modern controls
• Flat, Unsegmented Networks: Make it easy for attackers to move laterally undetected
• Minimal Downtime Windows: Scheduled maintenance may be limited to just hours per year
• Vendor Access Vulnerabilities: External access is a common initial attack vector

1. Application-Level Microsegmentation

Create Virtual Chambers around critical OT/ICS assets - without reconfiguring your networks.

• Insert a Virtual OT DMZ across segmented systems
• Enforce identity-based access where traditional IAM can't reach
• Lock access to software-defined identities, preventing credential abuse
• Enable contractor access with time-limited, least-privilege policies
• Establish secure hybrid-cloud communication across OT and IT
• Simplify compliance with logical controls that directly map to NERC CIP

Protected systems include:

• Distributed SCADA/EMS/ADMS systems
• Grid control centers
• Unmanned substations
• Remote facilities and safety instrumented systems (SIS)

2. Identity-Based Access Control

Every connection - user or device - is authenticated and authorized.

• Integrate with corporate IAM and multi-factor authentication
• Enforce just-in-time, scoped access for third-party vendors
• Establish time-limited credentials with full audit trails
• Prevent lateral movement and unauthorized access

3. Agentless Protection for Legacy OT

Secure systems that can’t be patched, updated, or modified.

• Deploy inline enforcement devices (e.g., Gatekeepers, MSGs) - no software installs needed
• Ensure fail-open operation to maintain uptime
• Block unauthorized port access with compensating controls
• Meet compliance without disrupting sensitive legacy systems

4. Secure Communication & Monitoring

Visibility and protection for data in transit and network activity.

• Encrypt control center traffic per CIP-012
• Log every access attempt with full context for audit readiness
• Monitor all activity to detect anomalies and policy violations

Why Not Firewalls Alone?
Unlike firewalls, identity-based policies are easier to manage, more scalable, and context-aware - enabling utilities to implement Zero Trust controls without the overhead of managing thousands of rules across substations.

Deployment Approach

Zentera’s implementation process is built for minimal disruption and maximum effectiveness:

1. Assessment & Planning – Map your current environment
2. Controlled Pilot – Validate functionality in a test system
3. Critical Asset Protection – Begin with agentless security for BES Cyber System
4. Enterprise-Wide Expansion – Roll out to all critical systems
5. Continuous Improvement – Refine policies as risks and regulations evolve

Why Zentera for Utilities

• Non-Disruptive Deployment: Overlay networks without reconfiguration
• Defense-in-Depth by Design: Microsegmentation complements existing tools
• Centralized Policy, Distributed Enforcement: Scalable, consistent security
• Future-Ready: Built for evolving CIP compliance and threat landscapes