Operational technology (OT) supply-chain risk is typically framed around software provenance, vendor assurance programs and threat intelligence. But for many industrial organizations, one of the most immediate and practical supply-chain risks lies much closer to home: third-party remote access to critical systems and assets.
Suppliers, OEMs, contractors and service providers routinely connect into production environments to perform maintenance, troubleshooting and other key tasks. These connections are legitimate and often essential — but they can nonetheless create pathways into sensitive systems that weren’t designed for broad external connectivity.
Because external work and support are crucial to day-to-day industrial operations, the solution to this challenge is not to eliminate supplier access. Instead, organizations need to ensure that third-party access is tightly controlled, continuously monitored and properly contained.
Traditional perimeter-based approaches struggle to address a reality in which external vendors and suppliers need regular access to mission-critical systems. Many legacy tools, including most VPNs, place third parties on broad network segments with far more access than necessary. If credentials are compromised or a vendor environment is breached, attackers may be able to pivot into the networks of the organizations that vendor supports, causing widespread operational disruption.
Reducing this exposure requires a shift away from network-centric trust models toward more granular, identity- and asset-based access control. This starts with understanding who needs access, what systems they actually need to reach, and under what conditions access should be granted. From there, organizations can begin limiting connectivity to only the specific assets, applications, and workflows required for a given task.
Equally important is limiting the blast radius of a potential incident. Even if a supplier account or remote session is compromised, the impact should be constrained by segmentation, least-privilege policies, and controls that prevent unrestricted lateral movement.
Another major consideration is visibility. Many industrial organizations do not have a complete inventory of all third-party connections into OT environments, particularly when access has accumulated over years of maintenance contracts, emergency support arrangements, and temporary vendor projects.
And even when organizations know a vendor is connected, they likely have little or no visibility into what that person is actually doing within the environment or whether their activity deviates from expected behavior. This problem is compounded by shared vendor accounts, which make it difficult to determine which individual technician or engineer is behind a particular session. Without visibility into who is connecting and what actions they take while connected, controlling third-party access and ensuring operational continuity become much harder. This is why more industrial organizations are turning to security solutions designed specifically to manage third-party OT access — providing centralized visibility, identity-based access control and real-time session monitoring and supervision. But securing third-party access and improving visibility into remote connections are only part of the equation. None of these measures will be viable if they slow production or complicate critical support workflows. Indeed, for many OT teams, the biggest challenge is strengthening security without disrupting operations or impacting uptime.
The good (and perhaps surprising) news is that greater control does not have to create operational friction. With the right approach, organizations can give their vendors and suppliers fast, reliable access while still enforcing identity-based authentication, restricting unnecessary connectivity, and maintaining visibility into every session. The goal is not to add complexity for operators or vendors, but to reduce exposure in ways that align with how industrial environments function day-to-day.
As supplier connectivity continues to expand, organizations should be asking a new set of questions:
- Do we know which third parties have access to our production environments?
- Do they have access only to the systems they need?
- Can we continuously monitor vendor activity and trace actions to an individual user?
- What happens if that access is misused or compromised?
The answers to these questions increasingly define the difference between resilient OT operations and unnecessary exposure to third-party access risks.
To learn more, visit the Cyolo booth at the ISA OT Cybersecurity Summit, taking place June 16-18, 2026 in Prague. Register now to claim your exclusive VIP gift on-site at the event.
