Key Points
- Enforce MFA, least privilege, and brokered jump access on the IT-managed systems that interface with OT networks.
- Isolate assets into zones and control conduits to contain potential breaches.
- Schedule vendor machine windows and use compensating controls for when patch deployments are delayed.
- Centralize logs, track anomalies, and regularly test incident response to keep teams prepared.
- Limit third-party access by applying approvals and time-bound credentials on the IT systems used to reach OT environments.
- Track risks, fixes, and exceptions so you can continuously strengthen your security posture without disrupting operations.
Operational technology (OT) systems are the backbone of industrial operations. They play a crucial role in delivering and maintaining essential services, including manufacturing and energy distribution.
Any disruptions within these settings can lead to costly downtime, safety hazards, and even environmental damage, which is why they require robust protection.
But implementing operational technology cybersecurity isn’t easy. It requires adopting a balanced approach that reduces risks and keeps physical processes running.
Much of this work starts on the IT systems that connect to OT. These are the areas where modern security tools can be applied effectively.
Securing operational technologies (OT) environments without disruptions
📌Prerequisites
- A comprehensive asset inventory for ICS, IIoT, HMIs, PLCs, historians, gateways, and supporting Windows hosts Kroll.
- A defined business criticality and safety impact for key processes.
- A list of named owners for each OT zone and shared vendors.
- A ticketing and change control workflow for maintenance windows.
- A centralized log collection from OT-adjacent systems wherever feasible.
Step 1: Enforce identity-first access controls for OT systems
Goal: Limit user access to OT systems and tightly control the actions they can take
Actions:
- Require multi-factor authentication (MFA) for all users who can access the IT systems used to enter OT environments to prevent unauthorized entry.
- Use secure access gateways, such as brokered jump hosts or Zero Trust Network Access (ZTNA) solutions, to terminate sessions outside of controlled networks.
- Provide time-limited, role-specific credentials to technicians and vendors.
These security measures align with some of the widely recommended access hardening protocols for OT environments.
Step 2: Segment OT networks and control data flows
Goal: Limit lateral movement within networks and protect critical assets
Actions:
- Organize OT assets by function and risk, and group them into zones designed and enforced through the supporting IT infrastructure.
- Restrict communication flows through DMZs or secure conduits to only necessary connections and use one-way data flows to historians where possible.
- Apply allow-listing rules on inter-zone firewalls and schedule regular policy reviews.
Design-time segmentation is another core OT cybersecurity principle recommended in the public and private sectors.
⚠️Important: Never allow direct access from the corporate network to PLCs, SCADA, or other control devices.
Step 3: Govern patching to reduce risks and prevent outages
Goal: Reduce security vulnerabilities while maintaining operational continuity
Actions:
- Align your patching schedules with vendor maintenance windows to minimize disruptions.
- Document exceptions during patching and add compensating controls, such as stricter access rules, additional monitoring, and account hardening.
- Monitor the age and risk level of recorded patch exceptions until they’re resolved.
Implementing a balanced approach that combines quick wins, segmentation improvements, and planned remediation is recommended because it strengthens the security posture of OT systems without compromising operational stability.
Step 4: Monitor OT boundaries and test incident response
Goal: Proactively detect and respond to threats before they become business-impacting incidents
Actions:
- Gather logs from jump hosts, Active Directory, VPNs, firewalls, and IT-OT gateways.
- Establish baseline normal behaviors and set up alerts for anomalies (e.g., new protocols, unexpected admin logons, and historian spikes).
- Conduct tabletop exercises and limited-scope functional tests to verify that incident response is functioning properly.
Continuous monitoring and tested response plans are emphasized in government OT security frameworks, more specifically for the IT systems that protect and support them.
Step 5: Secure vendor and third-party access to OT zones
Goal: Enable secure and controlled maintenance from vendors and third-party providers
Actions:
- Approve vendors per OT zone and ensure there are defined scopes and emergency access paths.
- Implement per-visit approvals, enable session recording where possible, and expire credentials immediately after use.
- Create a central repository for vendor contacts and documents.
Controlling vendor access is a high-impact mitigation strategy across OT security best practices. It reduces the risk of unauthorized actions and credential misuse, especially in environments where third parties regularly conduct troubleshooting.
Step 6: Drive continuous improvement through measured risk reduction
Goal: Demonstrate progress without disrupting operations
Actions:
- Maintain a living risk register with clear owners, defined treatments, and due dates to ensure every risk is tracked, accountable, and actively managed.
- Report progress and share key metrics, such as the number of closed risks per quarter, the oldest open exceptions, and zone coverage.
- Refine playbooks and access scopes by conducting post-incident or post-exercise reviews to identify what worked and what didn’t.
A roadmap that includes iterative updates and regular testing is encouraged by multiple industry sources. It helps MSPs adapt to emerging threats, regulatory changes, and evolving operational needs.
Summary of best practices for securing OT environments
| Step | Goal/Value |
| Enforce identity-first access controls for OT systems. | Limit user access to OT systems and the actions they can take. |
| Segment OT networks and control data flows. | Limit lateral movement within networks and protect critical assets. |
| Govern patching to reduce risks and prevent outages. | Reduce security vulnerabilities while maintaining operational continuity. |
| Monitor OT boundaries and test incident response. | Proactively detect and respond to threats before they escalate. |
| Secure vendor and third-party access to OT zones. | Enable secure and controlled maintenance from vendors and third-party providers. |
| Drive continuous improvement through measured risk reduction. | Demonstrate progress without disrupting operations. |
A quick overview of OT environments
OT environments are hardware and software systems that monitor and control physical devices and processes in infrastructure and industrial settings. These include:
- Factories
- Power plants
- Transportation and aviation facilities
- Water treatment facilities
OT systems were once mostly mechanical, but as devices become smarter and more connected, there’s a growing convergence between traditional IT and modern OT systems.
As a result, these infrastructures have become more vulnerable to cyberattacks. The increased connectivity between IT and OT expanded the potential attack surface, making it easier for threat actors to infiltrate critical systems.
With these risks in mind, MSPs must adopt OT cybersecurity strategies that can strike a balance between safety and operational continuity. This means developing security models that take legacy systems and uninterrupted uptime into account.
Enhancing OT cybersecurity and compliance oversight with NinjaOne
NinjaOne can help MSPs enhance OT cybersecurity and compliance oversight using the following services:
| NinjaOne Service | What it is | How it helps |
| Access Enforcement | Automates MFA-related policies and deploys hardening scripts on Windows endpoints that sit at the edge of OT environments. | Allows you to standardize boundary security practices without manual configuration |
| Change and Exception Tracking | Opens and expires tickets for patch deferrals, vendor sessions, and firewall rule changes | Makes managing exceptions easier and demonstrates compliance with industry standards |
| Monitoring Assist | Collects endpoint and gateway telemetry at the IT-OT boundary and alerts on unauthorized tools or services | Enhances threat detection and response at IT-OT boundaries |
| Reporting | Generates dashboards showing exception age, completed remediation items, and other system insights to support audit readiness. | Helps prove compliance support and strengthens client relationships |
Securing OT environments through controlled access, intentional segmentation, and continuous monitoring
Controlled access, intentional network segmentation, and continuous monitoring are some of the best practices for securing OT environments.
While patch deployments must align with the realities of production, they should never go unmonitored or unverified. Each update must be assessed for potential technical impact and scheduled properly to minimize disruptions.
Vendor and third-party access should never be a gray area. It must have clear scopes and defined durations to prevent unnecessary exposure. Regular logging, auditing, and readiness exercises can help strengthen defenses by keeping teams alert for anomalies.
Combine these security practices with measurable reporting, and you can create a resilient framework for keeping OT environments safe and efficient.
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