How Meridian helps
We review existing architectures, define zones and conduits, and produce practical segmentation recommendations suitable for brownfield and live industrial environments.
Common OT Security Problems
Flat OT Networks
Many industrial environments evolve into flat operational technology networks with limited segmentation, unclear trust boundaries, and uncontrolled communications between systems.
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Overview
Flat OT networks are common within legacy industrial environments where systems have expanded over time without a defined security architecture.
Engineering workstations, HMIs, PLCs, historians, vendor access solutions, and operational servers may all communicate across shared switching infrastructure with limited segmentation or traffic control.
This increases the potential impact of faults, unauthorised access, malware propagation, misconfiguration, and lateral movement across operational systems.
Typical impact
Typical impact
- increased lateral movement risk
- poor separation between critical systems
- difficult firewall implementation
- limited asset visibility
- weak audit evidence
Typical Indicators
Flat OT architectures often develop gradually through project modifications, temporary connections becoming permanent, unmanaged switch deployment, or historic operational decisions made before modern OT cybersecurity requirements existed.
Typical Indicators
- Large shared Layer 2 operational networks
- Limited or absent security zoning
- Shared switches between unrelated systems
- Minimal traffic filtering between operational assets
- Engineering laptops connected directly into control networks
- Poor visibility of system-to-system communications
- Vendor remote access without clear segmentation
- Legacy infrastructure with unclear ownership
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Placeholder image showing a simplified flat OT network architecture
Operational and Security Risks
A flat OT environment increases operational and cybersecurity risk because unrelated systems can communicate more broadly than necessary.
This can allow failures, malware, misconfiguration, or unauthorised activity to affect larger portions of the operational environment than intended.
Operational and Security Risks
- Increased lateral movement opportunities
- Reduced containment during incidents
- Difficulty applying security controls consistently
- Poor separation between business and operational systems
- Reduced visibility of critical communications
- Greater complexity during troubleshooting and outages
- Challenges demonstrating assurance or compliance
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Placeholder image representing lateral movement within industrial networks
Typical Engineering Challenges
Improving segmentation within operational environments is rarely a simple firewall exercise.
Industrial systems may contain legacy protocols, vendor restrictions, operational dependencies, unsupported assets, or limited outage windows that constrain how changes can be implemented.
Typical Engineering Challenges
- Legacy PLC and SCADA infrastructure
- Unsupported operating systems
- Unknown or undocumented dependencies
- Limited maintenance windows
- Operational resistance to disruption
- Third-party vendor constraints
- Incomplete network documentation
- Mixed ownership across packages or sites
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Placeholder image showing legacy industrial infrastructure
How Meridian Consultants Supports Clients
Meridian Consultants supports clients by reviewing existing operational technology architectures and identifying practical opportunities for improved segmentation, visibility, and assurance.
The focus is on proportionate engineering-led improvements suitable for operational environments rather than generic IT security approaches.
How Meridian Consultants Supports Clients
- OT architecture review
- Zones and conduits development
- Network segmentation assessment
- Firewall and conduit review
- Asset and interface analysis
- Identification of critical trust boundaries
- Supplier and package interface review
- Support for IEC 62443 aligned approaches
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Placeholder image showing OT segmentation and zones review
Typical Outputs
Outputs are intended to support practical engineering assurance, project decision-making, and future remediation planning.
Typical Outputs
- Segmentation review reports
- Zones and conduits diagrams
- Network architecture observations
- Asset and interface registers
- Risk identification records
- Firewall review comments
- Residual risk observations
- Technical recommendations
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Placeholder image showing engineering deliverables and reports
Related guidance
Continue through related service, problem and resource pages for the same OT cybersecurity topic.
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