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Industrial organizations are increasingly dependent on remote connectivity. Engineers, vendors, maintenance teams, and cybersecurity personnel often need access to operational technology (OT) and industrial control systems (ICS) without being physically present at a facility.

This shift improves efficiency and reduces downtime. However, it also introduces significant cybersecurity risks. Many high-profile attacks on critical infrastructure have exploited remote access pathways, exposing weaknesses in authentication, visibility, and third-party access controls.

As a result, secure remote access for OT/ICS has become a strategic priority for cybersecurity professionals and industrial leaders. The challenge is not simply enabling connectivity. It is providing secure, controlled, and auditable access without disrupting operations.

What Is Secure Remote Access for OT/ICS?

Secure remote access for OT/ICS refers to technologies and processes that allow authorized users to connect to industrial systems from external locations while maintaining strong security controls.

Unlike traditional enterprise remote access, OT environments have unique requirements. Industrial systems often support critical processes, safety functions, and continuous operations. Downtime can result in production losses, environmental incidents, or safety concerns.

A secure remote access solution must therefore balance cybersecurity with operational reliability.

Understanding OT and ICS Environments

OT environments include systems that monitor and control physical processes. Examples include:

• Supervisory Control and Data Acquisition (SCADA) systems
• Distributed Control Systems (DCS)
• Programmable Logic Controllers (PLCs)
• Human Machine Interfaces (HMIs)
• Industrial sensors and actuators

These systems are commonly found in manufacturing, energy, utilities, transportation, and critical infrastructure sectors.

Common Remote Access Use Cases

Organizations typically require remote access for:

• Vendor maintenance and support
• Remote troubleshooting
• Engineering and programming activities
• System monitoring
• Emergency response
• Multi-site operational management

While these use cases create business value, they also create potential entry points for attackers if access is not properly secured.

The Risks of Unsecured OT/ICS Remote Access

Many industrial environments still rely on legacy VPNs, shared accounts, or permanently enabled remote connections. These approaches can create significant security gaps.

Expanded Attack Surface

Every remote access connection introduces a potential pathway into the industrial network.

Attackers frequently target remote access services because they provide direct access to critical systems. Compromised credentials, misconfigured VPNs, and exposed remote desktop services remain common attack vectors.

Third-Party and Vendor Risks

Industrial organizations often depend on external vendors for support and maintenance.

Without proper controls, vendors may have excessive privileges, persistent access, or limited oversight. A compromise affecting a trusted supplier can quickly become a risk to the industrial environment.

Compliance and Regulatory Concerns

Many regulatory frameworks now emphasize secure remote access controls.

Examples include:

• NIST Cybersecurity Framework
• IEC 62443
• NERC CIP
• TSA cybersecurity directives
• Industry-specific critical infrastructure requirements

Organizations must demonstrate that remote access is controlled, monitored, and auditable.

Operational Disruption and Safety Impacts

Cyber incidents affecting OT systems can have consequences beyond data loss.

Potential outcomes include:

• Production downtime
• Equipment damage
• Process interruptions
• Safety incidents
• Environmental impacts

For industrial organizations, secure remote access is therefore both a cybersecurity and operational resilience requirement.

Core Requirements for Secure Remote Access in OT/ICS

Not all remote access solutions are designed for industrial environments. Cybersecurity leaders should focus on several critical capabilities.

Zero Trust Access Controls

Traditional remote access models often assume trust after authentication.

Zero trust approaches continuously verify users and devices before granting access. Access decisions are based on identity, context, and policy rather than network location.

Key principles include:

• Least privilege access
• Continuous verification
• Explicit authorization
• Segmented access paths

Multi-Factor Authentication (MFA)

Passwords alone are no longer sufficient. MFA significantly reduces the likelihood of credential-based attacks by requiring additional verification factors.

Industrial organizations should require MFA for:

• Employees
• Contractors
• Vendors
• Privileged administrators

Session Monitoring and Recording

Visibility is essential in OT environments. Session monitoring enables organizations to observe user activities in real time. Session recording creates a forensic trail for investigations, audits, and compliance reviews.

Granular User Permissions

Users should only have access to systems necessary for their roles.

Strong solutions provide:

• Role-based access control
• Asset-level permissions
• Time-based access policies
• Temporary access provisioning

These controls reduce the impact of compromised accounts.

Secure Connectivity and Encryption

All communications should be protected using strong encryption.

Organizations should evaluate:

• End-to-end encrypted sessions
• Secure tunneling technologies
• Device authentication
• Protected communication channels

Audit Trails and Compliance Reporting

Comprehensive logging supports both security operations and compliance requirements.

Important capabilities include:

User activity logs

• Access request histories
• Session records
• Automated reporting

These records help demonstrate accountability and regulatory compliance.

Challenges of Implementing Secure Remote Access in Industrial Environments

Despite the benefits, deployment can be complex.

Legacy Systems and Unsupported Assets

Many industrial systems were designed long before modern cybersecurity requirements emerged.

Older assets may:

• Lack support for MFA
• Use outdated operating systems
• Depend on proprietary protocols
• Require specialized access methods

Solutions must often compensate for these limitations without affecting operations.

Balancing Security and Operational Availability

Industrial organizations cannot simply prioritize security at the expense of uptime.

Remote access controls must be implemented carefully to avoid:

• Production interruptions
• Maintenance delays
• Increased operational complexity

Successful programs align security objectives with operational requirements.

Managing Vendor and Contractor Access

Many facilities work with dozens or even hundreds of external service providers.

Managing access manually becomes difficult as environments scale.

Organizations need centralized methods to:

• Approve access requests
• Grant temporary privileges
• Monitor activities
• Remove access when work is complete

Network Segmentation Complexity

Effective OT security often depends on network segmentation. However, segmented environments can complicate remote connectivity.

Remote access solutions must provide secure pathways across zones while maintaining segmentation policies and minimizing lateral movement opportunities.

How to Evaluate Secure Remote Access Solutions for OT/ICS

When assessing vendors, organizations should use a structured evaluation framework.

Security Capabilities

Look for:

• Zero trust architecture
• MFA support
• Granular access controls
• Session monitoring
• Session recording
• Threat detection capabilities

OT Compatibility

Industrial requirements differ from traditional IT environments.

Evaluate support for:

• Legacy systems
• Industrial protocols
• Air-gapped environments
• Vendor workflows
• Critical infrastructure deployments

Deployment Flexibility

Different organizations have different requirements.

Potential deployment models include:

• Cloud-based
• On-premises
• Hybrid architectures

The ideal approach depends on operational, regulatory, and security considerations.

Scalability and Management

As organizations grow, management complexity increases.

Evaluate:

• Centralized administration
• Multi-site support
• User lifecycle management
• Reporting capabilities
• Integration with identity systems

Leading Secure Remote Access Solutions for OT/ICS

Several vendors offer solutions designed to improve remote access security in industrial environments.

Claroty xDome Secure Access

Claroty is widely recognized for its focus on OT cybersecurity. Its secure access platform is designed specifically for industrial environments and integrates with broader OT visibility capabilities.

Key features include:

• Purpose-built OT access controls
• Vendor access management
• Session monitoring and recording
• Asset-aware access policies
• Centralized administration

This solution is best for organizations seeking an OT-focused remote access platform with strong visibility into industrial assets. One potential consideration is that deployment may require coordination with broader OT security initiatives and existing infrastructure.

Cyolo

Cyolo uses an identity-centric architecture based on zero trust principles. The platform focuses on securing workforce and third-party access while minimizing network exposure.

Key features include:

• Identity-based access controls
• Zero trust architecture
• MFA integration
• Secure third-party access
• Flexible deployment options

This solution is best for organizations that manage significant contractor and vendor access requirements. A potential challenge is ensuring alignment with existing identity and access management strategies.

Zscaler Private Access

Zscaler extends its broader zero trust platform to remote access use cases. The solution replaces traditional VPN-based approaches with application-level access controls.

Key features include:

• Zero trust network access
• Cloud-native architecture
• Identity-driven policies
• Reduced attack surface
• Centralized management

This solution is best for enterprises pursuing broader zero trust modernization programs. Organizations with highly specialized OT requirements may need additional planning and integrations.

Palo Alto Networks Prisma Access

Prisma Access combines remote connectivity with broader security capabilities. Organizations already invested in the Palo Alto ecosystem may benefit from integration and operational consistency.

Key features include:

• Cloud-delivered security services
• Identity-aware access
• Threat prevention
• Security policy enforcement
• Global scalability

This solution is best for organizations standardizing on a comprehensive security platform. The tradeoff is that it may introduce more complexity than purpose-built OT access solutions.

Tailscale

Tailscale has gained attention for simplifying secure connectivity through modern networking architecture.

The platform can reduce operational complexity while maintaining strong security controls.

Key features include:

• Identity-based networking
• Encrypted peer-to-peer connectivity
• Rapid deployment
• Simplified management
• Cross-platform support

This solution is best for organizations seeking straightforward secure connectivity with minimal infrastructure requirements. Highly regulated industrial environments may require additional governance and monitoring capabilities alongside the platform.

Best Practices for Securing OT/ICS Remote Access

Technology alone is not enough. Organizations should also implement strong operational practices.

Enforce Least Privilege Access

Users should only receive the minimum access required to perform their tasks. Regular reviews help prevent privilege accumulation over time.

Continuously Monitor Remote Sessions

Monitoring enables security teams to identify unusual behavior before it becomes a larger issue. Real-time visibility improves detection and response capabilities.

Review and Remove Unused Access

Dormant accounts create unnecessary risk.

Organizations should routinely:

• Remove inactive accounts
• Disable expired vendor access
• Review user permissions
• Validate access requirements

Segment Critical Industrial Assets

Segmentation limits attacker movement if a remote access account becomes compromised. Critical systems should be isolated using clearly defined security zones.

Establish Vendor Access Policies

Vendor access should be governed through formal policies.

Requirements should include:

• MFA
• Time-limited access
• Approval workflows
• Activity monitoring
• Session logging

The Future of Secure Remote Access in OT/ICS

Industrial cybersecurity is moving toward identity-centric and zero trust architectures.

Several trends are shaping the future of OT remote access:

• Increased adoption of zero trust principles
• Greater use of identity-based controls
• Expanded session monitoring capabilities
• Stronger regulatory oversight
• Increased convergence between IT and OT security programs
• Growing reliance on third-party service providers

Organizations that modernize remote access today will be better positioned to address future threats and compliance requirements.

Conclusion