{"id":86833,"date":"2026-08-17T14:31:17","date_gmt":"2026-08-17T12:31:17","guid":{"rendered":"https:\/\/fhi.nl\/?post_type=news&p=86833"},"modified":"2026-08-17T14:31:19","modified_gmt":"2026-08-17T12:31:19","slug":"van-vpn-naar-zero-trust-een-stapsgewijze-aanpak-voor-ot","status":"publish","type":"news","link":"https:\/\/fhi.nl\/en\/news\/van-vpn-naar-zero-trust-een-stapsgewijze-aanpak-voor-ot\/","title":{"rendered":"From VPN to Zero Trust: a step-by-step approach for OT"},"content":{"rendered":"
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\n\t\t\t\t\tFrom VPN to Zero Trust: a step-by-step approach for OT\t\t\t\t<\/h1>\n\n\t\t\t\t
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Ransomware, supply chain attacks, and stricter legislation are putting pressure on industrial organizations to increase their cyber resilience. In this context, the term is appearing increasingly often. Zero Trust<\/em>. But how do you apply a security strategy from the IT world in factories where availability and continuity come first?<\/strong><\/p>\n

Zero Trust revolves around a simple principle: never trust, always verify. Access is granted only after the account, device, IP address, and location have been verified \u2013 even when dealing with an internal network. Organizations that apply Zero Trust principles in their OT architecture are better protected against external and internal threats.<\/p>\n

The idea that every connection poses a potential threat aligns well with modern cyber threats. However, operational technology (OT) requires a different approach than traditional IT. After all, production lines, power plants, water treatment plants, and process installations must operate stably for years. A software update or new security measure has immediate consequences for production and continuity. Therefore, Zero Trust in OT calls for a pragmatic and step-by-step approach.<\/p>\n

The lesson of Colonial Pipeline<\/h2>\n

The fact that OT systems are an attractive target for cybercriminals is evident from, among other things, the 2021 ransomware attack on Colonial Pipeline, the largest oil pipeline company in the United States. Attackers gained access to the network via a compromised VPN account without multi-factor authentication. As a precaution, the pipeline was temporarily shut down.<\/p>\n

The consequences were enormous: planes remained grounded, (school) buses did not run, and people could not get to work. The damage ran into the tens of millions.<\/p>\n

More recently, in April 2026, US federal agencies warned of an Iran-linked cyber threat against water and wastewater systems in the US. The danger was averted just in time, but the issue once again highlighted the importance of protecting critical infrastructure from hackers. The question, therefore, is not whether organizations should adopt Zero Trust, but what the most effective approach is.<\/p>\n

1. Start with operator and engineer workstations<\/h2>\n

Cyberattackers rarely target the PLC or DCS controller directly. They usually utilize existing access paths, such as remote access solutions, management systems, or compromised accounts. Operator and engineer workstations therefore form the logical starting point for a Zero Trust architecture. HMIs, SCADA platforms, DCS environments, and PLCs are managed from these systems. Consequently, an infected engineering laptop or stolen account can cause more damage than a vulnerability in the process itself.<\/p>\n

Measures such as multifactor authentication, individual accounts, granular access rights, and improved monitoring are relatively easy to implement. They immediately give organizations more control over access to critical systems without requiring an overhaul of the entire OT infrastructure. <\/p>\n

2. Limit later movement through segmentation<\/h2>\n

When users and workplaces are better secured, the focus shifts to the network. Network segmentation forms an important part of Zero Trust. The goal is simple: systems should only communicate when there is an operational necessity to do so.<\/h2>\n

In practice, this means a clear separation between office IT, process networks, and separate production lines or installations. However, effective segmentation goes beyond merely separating networks. For example, a packaging line does not automatically need access to the PLC of an adjacent filling line. Nor is it necessary for an HMI to connect to all controllers within a factory.<\/p>\n

By allowing only necessary communication according to the need-to-know<\/em> in principle, it becomes more difficult for attackers to move within a network. Precisely this limitation of lateral movement is one of the most important security gains of a Zero Trust architecture.<\/p>\n

3. Take a critical look at remote access<\/h2>\n

Remote access by suppliers and maintenance parties is indispensable in industrial environments. At the same time, remote access often proves to be a weak link in practice. Outdated VPN solutions, shared accounts, and limited logging make it difficult to verify who accessed systems and when.<\/p>\n

A Zero Trust approach does not exclude remote access, but imposes stricter requirements on it. Access must be temporary, purpose-driven, and fully traceable. Suppliers are granted access only to the system they are required to maintain during the agreed maintenance period.<\/p>\n

Multifactor authentication, central access portals, and extensive logging offer companies better insight into the activities of third parties without limiting operational flexibility.<\/p>\n

4. Protect vulnerable legacy systems<\/h2>\n

Many OT environments contain systems that were designed before cybersecurity became a design criterion.<\/p>\n

Older PLCs, HMIs, analyzers, and control components often function perfectly, but support modern safety functions little to none. Replacement is not always feasible. Equipment sometimes needs to be available 24\/7, spare parts are scarce, or the software runs on outdated control systems.<\/p>\n

In such situations, it is more effective to organize security around the system. Consider strictly controlled access, secure intermediate layers, network segmentation, and continuous network monitoring.<\/p>\n

This provides additional insight into anomalous behavior, even when the legacy system itself offers hardly any security options.<\/p>\n

5. Don't forget the human factor<\/h2>\n

Technology alone is not enough. Zero Trust only succeeds when cybersecurity, engineering, maintenance, and operations work together.<\/p>\n

In practice, security measures are often circumvented when they slow down daily work too much. That risk is particularly high when operators and maintenance technicians are under time pressure to make quick decisions.<\/p>\n

Training and on-the-job explanations help create understanding. It is also important that security measures align with daily work practices. Engineers do not need to become cybersecurity specialists, but they must understand why individual accounts, controlled remote access, and reporting anomalous behavior contribute to the security of the process.<\/p>\n

Zero Trust is a mindset<\/h2>\n

For industrial organizations, Zero Trust is not a spectacular new way of working. The greatest gains lie in relatively simple measures: less uncontrolled access, fewer excessive privileges, and better insight into network traffic.<\/p>\n

It is precisely this step-by-step approach that makes Zero Trust suitable for OT. The goal is not to slow down production processes through extra controls, but to limit the impact of incidents. Zero Trust is therefore not an end destination, but a practical method to make cyber risks manageable without jeopardizing the continuity, security, and reliability of industrial processes.<\/p>\n

Source:<\/strong> Implementing Zero Trust in Operational Technology: A Practical Case Study<\/a><\/p>\n

Related events<\/h2>\n

FHI organizes various meetings and events where you learn more about cybersecurity and OT.<\/p>\n