Operational Technology (OT) includes the systems and software that control and monitor industrial processes and machinery. Because these systems are directly connected to industrial operations and critical infrastructure, a successful cyber attack can not only result in data loss, but also production downtime, safety incidents, or even physical damage. An OT penetration test makes these risks tangible by simulating realistic attack scenarios. This reveals vulnerabilities and misconfigurations that often go unnoticed during regular checks. The outcome: clear insight into the potential impact of cyber threats on continuity and safety, along with concrete recommendations to strengthen OT systems. In this way, cyber risks remain manageable and incidents can be prevented.
What is an OT pentest?
An OT pentest is a specialised security test in which realistic cyber attacks on industrial environments are simulated. The goal is to identify vulnerabilities in operational technology, such as SCADA systems, PLCs and other industrial control components. In addition, organisations receive concrete technical recommendations that enable them to strengthen their OT environment in a targeted and sustainable way against focused attacks, disruptions and sabotage. Where traditional IT pentests focus on digital infrastructure or applications, an OT pentest specifically examines the systems that control physical processes, often within critical sectors such as energy, manufacturing, transportation and water management. This test requires in-depth knowledge of industrial protocols and architectures and is carried out with maximum attention to the continuity and safety of the underlying processes.
Why is an OT pentest important?
Operational technology is indispensable for production processes and critical infrastructure. A successful attack can result in downtime, physical damage, or safety incidents. An OT pentest helps organisations identify and manage risks in a timely manner by:
- Uncovering vulnerabilities and misconfigurations in systems, configurations and network segmentation that would otherwise go unnoticed.
- Providing insight into the impact of attacks on the continuity, safety and reliability of processes.
- Assessing the effectiveness of existing security measures and offering concrete, actionable advice to structurally strengthen the OT environment.
- Supporting compliance with laws, regulations and standards (such as IEC 62443).
What are the challenges of pentesting OT?
Pentesting operational technology (OT) differs fundamentally from traditional IT pentests. While IT environments are often designed with flexibility and recovery functions in mind, OT environments are primarily focused on availability, safety and stability. This brings specific challenges.
Common challenges include:
- No tolerance for downtime: even minor disruptions can cause production stoppages or safety incidents, meaning tests must always be carried out in a non-intrusive manner.
- Vulnerable legacy systems: many devices and operating systems were not designed with security in mind and may respond unpredictably to intensive testing methods.
- Specialised protocols and equipment: industrial protocols (such as Modbus or Profinet) and systems (PLCs, SCADA, HMIs) require specific knowledge and tailored testing methods.
- Limited visibility into networks: documentation of OT environments is often incomplete, which means unknown connections or shadow IT may only come to light during a pentest.
- Coordination with operations: testing requires close collaboration with engineers and operators to minimise risks and ensure safe execution of test activities.
An OT pentest is therefore not a standard pentest, but a carefully tailored process that exposes vulnerabilities without jeopardising the continuity of critical processes.
Our OT Pentest Services
Our OT pentest services are based on an approach that ensures safety and continuity, with minimal impact on the production environment, so that critical processes can continue running without interruption. Depending on the organisation’s objectives, our OT pentests can be carried out from three different attack perspectives:
- Black box OT pentest: simulation of an external attacker without prior knowledge. Ideal to demonstrate what an attacker without prior knowledge can achieve.
- Grey box OT pentest: test scenarios based on insider access, such as through supplier portals or user accounts. Provides insight into lateral movement and escalation within the OT network.
- White box OT pentest: in-depth analysis with full documentation, configuration and source code. Particularly suitable for testing the security of specific components and architectures.
Our Technical Approach
Our approach combines technical depth with a pragmatic focus on operational continuity. The main areas of assessment are:
1. Architecture & Network Segmentation
- Analysis of zones, separations and firewall rules.
- Validation of the effectiveness of IT-OT separation.
- Assessment of external connections and remote access points.
2. Protocol Security
- Testing of industrial protocols used, such as Modbus, Profinet, DNP3, OPC-UA.
- Identification of missing encryption, authentication issues and possibilities for manipulation.
3. Component Assessment
- Inspection of PLCs, SCADA servers, DCSs and HMIs.
- Review of firmware, default settings, hardcoded credentials and configuration errors.
4. Authentication & Authorisation
- Evaluation of access management, password policies and remote access solutions (VPN, RDP, jump servers).
- Analysis of access logs and monitoring capabilities.
5. Vulnerabilities & Exploitation
- Controlled exploitation attempts such as privilege escalation or network pivoting.
- Always using non-intrusive techniques to avoid downtime.
6. External Access & Remote Support
- Analysis of vendor connections, often the weakest link in OT security.
- Evaluation of security measures around remote maintenance and support.
Safe Testing in Sensitive OT Environments
Our methodology is specifically designed for environments where downtime is not an option:
- Passive discovery instead of aggressive scanning.
- Manual validation of vulnerabilities rather than bulk automated tools.
- Close collaboration with engineers and operators during test execution.
Reporting
At the end of the OT pentest, you will receive a clear report providing strategic insight into the actual risks for your production environment, along with guidance to structurally reduce them, so you can immediately strengthen your OT environment. The report includes:
- Executive Summary: a strategic overview of the key risks and recommendations, written in a way that is understandable for management and executives.
- Prioritised Overview of Vulnerabilities: including technical explanations, why each issue poses a risk and the potential impact.
- Concrete and Actionable Advice: practical recommendations to remediate vulnerabilities, tailored to industrial realities.
- Third-Party Memorandum (optional): a formal summary that can be shared with customers, auditors, regulators, or other stakeholders, without disclosing sensitive details.
Why Computest?
✔ Specialised in OT pentesting.
✔ Safe testing methodology with minimal impact on your production environment.
✔ Broad scope: from network segmentation to PLCs and SCADA.
✔ IEC 62443-based approach.
✔ CCV-certified pentesting quality mark.
✔ OSCP/OSCE certified ethical hackers.
✔ Pragmatic and actionable advice.
Make your OT environment more secure with an OT pentest
Would you like to learn more about our OT pentest services or speak directly with a specialist? Contact us at pentest@computest.nl or fill out the contact form. We will get back to you within one working day to discuss your OT pentest needs and security challenges.