In the rapidly shifting landscape of Industrial Cybersecurity, the air gap is no longer a defense; it is a myth. As we move through 2025, the convergence of Operational Technology (OT) and Information Technology (IT) has created a complex web of interconnected assets that drive our global infrastructure. However, this connectivity comes at a high cost: an expanded attack surface that now spans from the cloud to the factory floor.
For industrial operators, the question is no longer if they should secure their systems, but how accurately they can identify their hidden risks. This is where an OT Security Assessment becomes the most critical tool in a CISO’s arsenal.
The State of OT/ICS Security in 2025: Why Assessments are Non-Negotiable
The industrial sector has entered a new era of “Hyper-Convergence.” Traditional Programmable Logic Controllers (PLCs) and Distributed Control Systems (DCS) are now being managed by AI-driven analytics and remote maintenance gateways. While this boosts efficiency, it also means that a single misconfiguration or a compromised IoT sensor can lead to catastrophic physical outcomes—ranging from environmental leaks to grid-wide blackouts.
Recent data from 2024 and early 2025 shows a significant pivot by threat actors. Attackers are moving away from purely financial targets (IT ransomware) toward “high-consequence” targets in manufacturing, energy, and water treatment. The primary goal is often no longer just data theft, but operational sabotage.
An OT Security Assessment is a specialized deep dive into these cyber-physical systems. Unlike a standard IT audit, it prioritizes Safety and Availability over Confidentiality. It identifies dormant vulnerabilities in legacy systems that cannot be patched and maps the intricate communication protocols (like Modbus, DNP3, and Profinet) that traditional scanners often ignore.
Top 10 OT Security Assessment Services for 2025
To help you navigate the crowded vendor landscape, we have analyzed the top providers specializing in the industrial space. These services are selected based on their technical rigor, protocol depth, and ability to deliver actionable roadmaps for critical infrastructure.
1. Dragos: The Intelligence-Driven Assessment
Dragos is often considered the gold standard in ICS security. Their assessment services are powered by the Dragos Platform and a team of practitioners who have responded to some of the world’s most significant industrial cyber-attacks.
- What makes them unique: Their “Neighborhood Watch” program and deep threat intelligence. They don’t just find vulnerabilities; they tell you which ones are being actively exploited by known threat groups targeting your specific industry.
- Best for: High-consequence environments like Power Grids and Oil & Gas.
2. Mandiant (Google Cloud): The Frontline Response Perspective
Since its acquisition by Google, Mandiant has integrated its legendary incident response expertise into a dedicated OT/ICS consulting practice. Their assessments are designed like “Pre-Mortems.”
- What makes them unique: They perform “Red Team” exercises specifically for OT, mimicking the actual TTPs (Tactics, Techniques, and Procedures) of nation-state actors. Their assessment concludes with a “Cyber Defense Center” roadmap to help you build a resilient SOC.
- Best for: Organizations that need to align their OT security with a mature, IT-integrated Security Operations Center.
3. Nozomi Networks: The Visibility Powerhouse
Nozomi excels in the “See Everything” category. Their assessment services revolve around their Guardian sensors, which provide real-time asset discovery and network visualization.
- What makes them unique: Their ability to handle massive, distributed environments. If you have 50 manufacturing sites globally, Nozomi’s assessment provides a unified “single pane of glass” view of every PLC and sensor across the entire fleet.
- Best for: Multi-site global manufacturing and Smart Cities.
4. Claroty: The Vulnerability & Risk Specialist
Claroty’s Focus assessment is built on a massive library of industrial protocol support. They specialize in finding the “un-patchable” risks in legacy hardware.
- What makes them unique: They offer a highly specialized Secure Remote Access (SRA) assessment, which is crucial in 2025 as more third-party vendors require remote connections to maintain industrial equipment.
- Best for: Pharmaceutical and Food & Beverage industries with heavy third-party vendor dependencies.
5. Palo Alto Networks: The Zero Trust OT Framework
Palo Alto has transitioned from being a “firewall company” to a leader in Zero Trust OT. Their assessment focuses on network segmentation and the implementation of least-privilege access at the industrial perimeter.
- What makes them unique: Their integration of Unit 42 threat intelligence. They assess how well your existing network hardware can be leveraged to create “Virtual Air Gaps” through micro-segmentation.
- Best for: Brownfield environments looking to modernize security without replacing expensive hardware.
6. Honeywell Forge: The OEM Advantage
As an Original Equipment Manufacturer (OEM), Honeywell knows the “insides” of the controllers better than most. Their Cyber Insights assessment is deeply rooted in the engineering side of operations.
- What makes them unique: They understand the “Process Control” logic. Their assessments don’t just look for IT bugs; they look for operational anomalies that could indicate a sophisticated attack on the process itself.
- Best for: Heavy industry users who already utilize Honeywell, Emerson, or Siemens control systems.
7. NCC Group: The Technical Deep-Divers
NCC Group is renowned for its low-level technical research. Their assessments often involve hardware-level penetration testing of IoT devices and embedded systems.
- What makes them unique: If you are developing a new industrial product or using custom-built IoT sensors, NCC Group will perform a “Full-Stack” assessment, from the circuit board to the cloud interface.
- Best for: Industrial IoT (IIoT) manufacturers and R&D-heavy sectors.
8. Tenable OT Security: The Asset Integrity Leader
Tenable (formerly Indegy) brings the rigor of Vulnerability Management (VM) to the OT world. Their assessment focuses on Asset Integrity-detecting changes in controller configurations.
- What makes them unique: They provide a “Snapshot” assessment of your PLC ladder logic. This allows you to see if a unauthorized user has changed the code that actually runs the machines.
- Best for: Water/Wastewater and small-to-medium utility providers.
9. Forescout: The Agentless Discovery Expert
Forescout’s assessment is built for the “Chaos of Connectivity.” They specialize in agentless discovery of every IP-connected device, including those that IT never knew existed.
- What makes them unique: Their assessments are exceptionally strong at identifying “Shadow OT”—consumer-grade devices or rogue modems plugged into the industrial network.
- Best for: Campus-style environments and healthcare facilities where OT and IT overlap significantly.
10. Cisco (Cyber Vision): The Network-Centric Assessment
Cisco leverages the industrial network itself (switches and routers) as a security sensor. Their assessment examines the health and security of the industrial backplane.
- What makes them unique: They focus on “Convergent Security.” Their assessments help bridge the gap between the Network Engineer and the Security Analyst, ensuring that the network infrastructure is inherently secure.
- Best for: Large-scale transportation and logistics hubs.
The Core Components: What a High-Quality Assessment Must Include
A “generic” assessment is a waste of capital. To ensure your assessment provides real value, it must break down into these five critical areas:
- Passive Asset Discovery: You cannot protect what you cannot see. The assessment must identify every PLC, HMI, and I/O module without “knocking them over” (crashing the system) with aggressive scans.
- Protocol-Deep Inspection: The service must understand the “language” of the machines. A scan that only sees “Port 502 open” is useless; a high-quality assessment identifies that “a Write command was sent to a specific register in a Schneider Electric PLC.”
- Network Topology Mapping: Visualizing the zones and conduits (following the IEC 62443 standard). The assessment should show you exactly how a threat could pivot from the guest Wi-Fi to the safety system.
- Operational Context: Risk must be ranked by Impact to Process. A vulnerability on a non-critical labeling machine is less important than a minor flaw on a high-pressure boiler control system.
- Regulatory Alignment: Whether it’s NIS2 in Europe, NERC CIP in North America, or local critical infrastructure mandates, the assessment should provide a “Compliance Map.”
Final Thoughts: Moving from Assessment to Action
In the OT ecosystem, an assessment is not the finish line-it is the starting gun. The “State of the Union” for your industrial security will change the moment a new technician plugs in a laptop or a new sensor is onboarded.
The goal for 2025 is to move toward Continuous Assessment. Use these top 10 services to establish your baseline, but ensure you have the tools and processes in place to monitor your “Cyber-Physical Health” in real-time.