When product Safety Meets Cybersecurity
prEN 50742, the forthcoming harmonised standard for protection against corruption in machinery, is set to become one of the most consequential compliance requirements of the EU Machinery Regulation 2023/1230 before its January 2027 application date. If your products are connected machines with any software, firmware, or external data interface that can influence a safety function. This standard defines what you will need to demonstrate to place them on the EU market.
EN 50742 Is Redefining Machine Compliance. It explicitly connects functional safety and cybersecurity. It aims to ensure that digital tampering cannot compromise the physical safety of machines. This shift is monumental for the industry because it forces a marriage between two departments that rarely spoke the same language in the past. As we transition into this new era of regulatory oversight, understanding the bridge between bits and blades is essential for any manufacturer.
Let’s explore what this means, why it matters, and how manufacturers can prepare for this fundamental shift in compliance.
prEN 50742 From Physical Safety to Digital Integrity
The concept behind prEN 50742 is clear: if a cyber event can make a machine unsafe, it belongs in the safety risk assessment. Traditionally, safety standards like EN ISO 12100 guided designers through identifying hazards and implementing safeguards. They focused primarily on mechanical, electrical, and ergonomic risks. This new standard expands its scope. It includes data integrity as a core pillar of a safe product. Also, it emphasizes network security and software reliability.
It applies to any machine capable of exchanging information with external devices, through Ethernet, Wi-Fi, USB, or cloud systems. While a simple unconnected hand drill remains outside this scope, nearly every modern industrial product now falls under its umbrella. For these products, the standard sets the new baseline for CE marking and legal market access in the European Union.
Every modification that can create safety risk like burn risk, or electrical shock, are considered as critical.
Key concepts
To understand the breadth of this standard, we must look at how it categorizes the ways a system can be compromised. The technical committee has identified three core concepts that every safety technician must now master:
Intervention:
Any action, whether intentional or accidental, that modifies the software or data of a machine.
Modification:
The actual physical or digital change resulting from that intervention.
Alteration:
Any unauthorized modification that may lead to a hazardous situation or danger.
These definitions reflect real-world industrial scenarios where safety is often compromised by “well-intentioned” shortcuts. A maintenance technician updating firmware without following proper safety protocols, or malware silently changing configuration parameters in a PLC, both count as interventions that require scrutiny. To manage these issues, prEN 50742 emphasizes the necessity for objective evidence. This includes digital logs or physical tamper-evident seals. These measures show exactly when and how changes occur.
Connectivity: The Hidden Weak Spot
Modern machines are full of connection points—wired networks, Wi-Fi links, USB ports, and specialized service tools. Each one of these is a potential vulnerability that can bypass traditional physical guarding. In the past, if you locked the cage, the machine was safe; today, someone can reach through the “digital cage” from a different continent.
Designers must now identify every communication path. They should either remove unnecessary ones or protect them through authentication. Encryption or physical controls can also be used. Even temporary connections used only for setup or maintenance must be evaluated. These connections need consideration for their long-term impact on the machine’s safety integrity. The message is clear: connectivity equals exposure, and exposure demands rigorous electrical safety and digital protection.
The access points
Before moving into the formal threat modeling process, it is important to categorize the types of access points common in industrial settings. These access points are often categorized by their accessibility and the technical skill needed to exploit them:
- Public Network Interfaces:
- Connections to the open internet or broad corporate networks that lack industrial-grade firewalls.
- Local Maintenance Ports:
- Physical USB or RJ45 ports located on the machine’s exterior, often used by field service engineers.
- Wireless Bridges:
- Bluetooth or Wi-Fi modules used for HMI tablets or remote monitoring sensors.
Identifying these points is the first step in creating a robust security architecture. Once these paths are mapped, the technician can apply the appropriate level of protection based on the potential risk to human life if that path is compromised. This mapping becomes a permanent part of the technical file required for compliance with the latest European regulations.
From Risk Assessment to Threat Modeling
prEN 50742 extends the risk-based approach of ISO 12100 to include digital threats through a process often called “Threat Modeling.” This approach significantly departs from traditional safety thinking. It requires technicians to think like an adversary. They go beyond just analyzing component wear and tear. You aren’t just asking “what if this relay fails?” but also “what if someone tells this relay to stay open?”
The process involves a systematic Five-Step Workflow:
- Identifying threats that could lead to hazardous situations.
- Finding vulnerabilities that allow those threats to occur.
- Estimating their impact on safety functions and performance levels.
- Implementing countermeasures or compensating measures to mitigate the risk.
- Documenting any residual risks for the end-user.
In this model, safety and security are treated as interdependent. A system can no longer be considered safe if it is not secure, because a security breach is now recognized as a potential root cause of a mechanical hazard. This integration ensures that the certification process covers the machine’s entire operational reality, including its digital footprint.
Expert Insight: When performing your first “Safety-Cyber” risk assessment, don’t start from scratch. Use your existing ISO 12100 list of hazards and ask: “Can a digital command trigger this hazard?” If the answer is yes, prEN 50742 applies to that function.
Countermeasures That Fit the Risk
The standard applies the same “reasonably practicable” principle used in traditional safety design. This is a relief for manufacturers, as it means you don’t need military-grade encryption for a simple conveyor belt. Measures must reduce risk effectively without being excessive or making the machine impossible to operate or maintain in a factory environment.
Common countermeasures range from basic digital hygiene to advanced cryptographic protections. When selecting these, safety technicians should consider the following options:
- Secure Logins: Moving away from universal “admin” passwords to individual, traceable user accounts.
- Role-Based Access Control (RBAC): Ensuring a machine operator cannot change safety timings that only a qualified engineer should access.
- Encrypted Communication: Protecting the data flow between the PLC and the cloud to prevent “man-in-the-middle” attacks.
- Physical Isolation: Using “Air Gapping” or physical keys to enable/disable remote access capabilities.
If vulnerabilities cannot be completely removed, often the case with legacy components, compensating controls are acceptable. For example, restricting physical access to an unprotected USB port by placing it inside a locked, monitored electrical cabinet is a valid mitigation strategy. Manufacturers must also include this information in their instructions, allowing users to maintain safe operation throughout the machine’s lifecycle.
Digital Evidence and Traceability
Traceability is one of the strongest pillars of prEN 50742. If a safety incident occurs, investigators must be able to determine if the software was modified prior to the event. Therefore, machines must now automatically record any intervention that can affect safety-related parameters.
These logs should be comprehensive, capturing the type of intervention, version identifiers, timestamps, and event correlations. However, the standard goes beyond just “saving a file”; it sets specific requirements for the integrity of these logs to ensure they remain a “single source of truth.”
For a log to be considered compliant under the new regulatory framework, it must meet several criteria:
- Automated Generation: The machine must create the record without human prompting.
- Tamper Protection: The logs themselves must be stored in a way that they cannot be deleted or altered by the person performing the intervention.
- Persistence: Records must be stored for at least five years to cover the typical lifespan and audit cycle of industrial equipment.
- Accessibility: The method for reading these logs must be documented and available to market surveillance authorities.
If digital tracking is technically impossible for a specific component, physical evidence such as serialized tamper-evident seals can be used. However, as we move toward “Industry 4.0,” automated digital logging is the preferred and more scalable solution. This requirement aligns perfectly with global cybersecurity standards like IEC 62443, or the AI Act. They create a unified bridge between safety documentation and cyber audit trails.
prEN 50742 Balancing Safety and Security
One of the most difficult tasks for a technician is managing the conflict between safety and security. Cybersecurity features must never compromise safety performance. For instance, a complex data encryption routine or a high-traffic firewall might introduce “latency” (delay) into a network. If that network is carrying a safety-critical signal, like an E-stop command, a delay of even a few milliseconds could cause a near-miss. In a worst-case scenario, it could result in a fatality.
Designers must ensure that security measures do not affect the required response time of safety functions. The goal is a delicate balance where the machine is secure from outside interference but remains lightning-fast in its response to local physical hazards. One cannot come at the expense of the other; they must work in tandem to achieve total compliance.
To help engineers navigate this complexity, the standard introduces a tiered approach to measuring the “strength” of the security required. This is done through a specific metric that mirrors the “Performance Level” (PL) or “Safety Integrity Level” (SIL) used in functional safety.
Introducing SRSL: Safety-Related Security Levels
prEN 50742 introduces the Safety-Related Security Level (SRSL)—a measure of how much cyber protection a safety function requires. This allows manufacturers to scale their security efforts based on the actual risk, rather than applying a one-size-fits-all approach that could be unnecessarily expensive or complex.
The SRSL ranges from 0 to 3, with each level requiring progressively more rigorous security controls:
| Level | Description | Typical Application |
| SRSL 0 | No protection required | Isolated systems with no external interfaces or ports. |
| SRSL 1 | Basic protection | Systems with low attack potential, protected by local physical barriers. |
| SRSL 2 | Moderate protection | Systems on a local industrial network with multiple layers of defense. |
| SRSL 3 | High protection | Maximum protection for systems with public or internet-facing connections. |
Each level defines specific requirements for authentication, authorization, integrity verification, and protection against both digital and physical tampering. As the exposure of the machine increases—for example, if it is connected to a remote monitoring cloud—the required SRSL increases accordingly. This ensures that the most “exposed” machines have the “thickest” digital armor.
Exposure and Attack Potential
The Exposure Level (EL) is a critical factor in determining the SRSL. It measures how “open” a system is to the outside world. An internal sensor communicating via a dedicated backplane has an EL of 0. In contrast, a machine accessible via a public web portal has an EL of 4. The logic is simple: the more people (or bots) that can reach the machine, the more stringent the cybersecurity must be.
Safety technicians should aim to reduce the Exposure Level whenever possible through network segmentation. By placing safety-critical PLCs on a separate, non-routable network segment, you can effectively lower the EL and, consequently, the required SRSL. This “Security by Design” approach is often cheaper and more effective than trying to secure a highly exposed system after it has been built.
Complementing this is the Attack Potential (AP). This metric combines the exposure, the likely capability of an attacker (e.g., a bored teenager vs. a state-sponsored hacker), and the “window of opportunity” an attacker has. A machine that is only connected for ten minutes a year for maintenance has a much lower AP than one that is online 24/7. The standard uses these ratings to provide a logical justification for the chosen protection level in the technical file.
Threat Modeling with STRIDE
To identify and categorize threats systematically, prEN 50742 adopts the STRIDE method. Developed originally by Microsoft, STRIDE has become the gold standard for analyzing software vulnerabilities. It transforms cybersecurity from a vague “feeling” into a structured safety activity that fits perfectly into a technician’s workflow.
The STRIDE acronym stands for:
- Spoofing: Someone pretending to be an authorized user or a trusted master controller.
- Tampering: Modifying safety parameters or overriding interlock logic.
- Repudiation: Performing an action and then erasing the logs so it cannot be traced back to the source.
- Information Disclosure: Leaking safety configurations that could be used to plan a physical bypass.
- Denial of Service (DoS): Flooding the network so the safety system cannot communicate, potentially causing a fail-safe shutdown (or worse, preventing one).
- Elevation of Privilege: An operator gaining the permissions of an administrator to bypass safety limits.
By using STRIDE, engineers can move through the machine’s architecture and identify specific mitigations for each threat. For example, to prevent Spoofing, you might implement digital certificates; to prevent Tampering, you might use checksums to verify software integrity at every boot-up. This structured approach is what regulatory bodies look for during an audit.
Documentation and User Information
As with all CE marking requirements, documentation is king. Manufacturers are now obligated to provide clear, actionable information regarding the machine’s digital security environment. It is no longer enough to provide a wiring diagram; you must provide a “digital map” of the safety-related software.
Users need to know exactly what they are responsible for maintaining. This includes information on:
- The machine’s intended security environment (e.g., “Must be behind a VPN”).
- Current software versions and specific configurations that affect safety.
- Clear procedures for how to access or modify these configurations safely.
- A list of authorized actions versus forbidden interventions.
The ultimate aim here is transparency. Operators and maintenance personnel should understand the system’s safety-related software environment as clearly as they understand its mechanical parts. If a technician doesn’t know that a specific USB port is a safety-critical interface, they cannot be expected to protect it.
prEN 50742 Integration with IEC 62443 and EU Regulations
One of the best features of prEN 50742 is that it doesn’t try to reinvent the wheel. It is designed to align closely with IEC 62443, the global standard for industrial cybersecurity. This allows manufacturers to choose between two implementation paths depending on their existing expertise:
- Approach A: A Risk analysis path based on traditional safety principles, ideal for smaller companies or those new to cybersecurity.
- Approach B: A path that directly uses the requirements of IEC 62443, perfect for large enterprises that already have a cybersecurity department.
This flexibility is crucial for global compliance. It also ensures that following this standard helps satisfy the requirements of the EU Machinery Regulation (2023/1230) and the upcoming Cyber Resilience Act (CRA). Together, these frameworks form a consistent and legally binding roadmap for modern manufacturing. You aren’t just following one standard; you are building a foundation for total European market access.
The Official EU Machinery Regulation (2023/1230)
Since prEN 50742 is designed to provide a “presumption of conformity” for the new European legal framework, linking to the actual regulation is essential. This allows your more advanced readers to see the legal text—specifically Annex III, Section 1.1.9 (Protection against corruption)—which serves as the legal mandate for the standard.
Why It Matters
At its core, this standard is about trust. When an operator pushes the start button on a 10-ton press, they must trust that the machine will behave exactly as intended. This includes both mechanical and digital performance. They need to know that a hacker in another country or a bug in a remote server cannot suddenly override the light curtains or the E-stop.
In our connected world, a single software update or an unauthorized login can cause a catastrophic physical event. prEN 50742 provides the industry with the tools to prevent these disasters, protecting not only the expensive equipment but, more importantly, the people who work alongside it every day. It moves cybersecurity from a “nice-to-have” IT feature to a “must-have” life-safety requirement.
Ignoring these requirements is no longer an option. As the “Decoded” series always emphasizes, staying ahead of the regulatory curve is the only way to avoid costly recalls or legal liabilities. The transition may seem daunting, but the standard provides a clear, step-by-step logic that any safety technician can follow.
How to Prepare: A prEN 50742 Checklist for Success
Manufacturers do not need to wait for the final publication of the standard to begin their journey toward compliance. In fact, starting now is the only way to ensure your product development cycles align with the new laws. Here is a practical roadmap for your technical team:
- Update Your Risk Assessment: Add a “Cybersecurity” column to your existing ISO 12100 documents.
- Map All Interfaces: List every port, wireless chip, and network protocol used by the machine.
- Classify Exposure: Assign an Exposure Level (EL) to each interface to see where your biggest risks lie.
- Implement Logging: Ensure your PLC or IPC is capable of creating tamper-protected event logs.
- Review Software Controls: Move away from shared passwords and ensure safety-critical code is “locked” behind authorized access.
- Verify Performance: Test your security measures (like firewalls) to ensure they don’t slow down your safety response times.
Starting these steps today will simplify your certification process when the standard becomes official. It demonstrates to your customers and to the authorities that your company is ready for the digital future of the European market. Safety is no longer just about hard-hats and steel-toed boots; it’s about secure code and protected networks.
Conclusion
The boundary between a cyber incident and a safety accident has officially vanished. prEN 50742 brings a unified answer to this challenge by treating cybersecurity as an inseparable part of functional safety itself. A truly safe machine today is one that cannot be easily tampered with, misconfigured, or corrupted by external digital forces.
As industries embrace the efficiency of digital transformation, this standard sets the stage for a new generation of trustworthy automation. We are moving toward machines that are not only powerful and connected but also “Safe by Design” in every sense of the word. At Regulatory Decoded, we believe that understanding these shifts is the key to engineering excellence.
Frequently Asked Questions about prEN 50742
What is prEN 50742? prEN 50742 is a draft European harmonized standard developed under CENELEC Technical Committee 44X. Its full title is “Safety of machinery — Protection against corruption.” It provides manufacturers with a technical framework for meeting the protection-against-corruption requirements of EU Machinery Regulation 2023/1230, specifically Annex III, Section 1.1.9. The standard addresses both accidental and intentional modification of safety-related software, data, and hardware interfaces in connected machines.
When will prEN 50742 become mandatory? The EU Machinery Regulation 2023/1230 becomes mandatory on 20 January 2027. Any machine placed on the EU market after that date must comply with the protection-against-corruption requirements of Annex III. The prEN 50742 standard, currently in DIS ballot phase as of December 2025, is expected to be published in 2026 and harmonized under the Machinery Regulation before the January 2027 deadline. Manufacturers are encouraged to adopt its principles now, since compliance must be demonstrable from the first day of the Machinery Regulation’s application.
Which machines does prEN 50742 apply to? The standard applies to any machine that includes hardware components, interfaces, or software capable of influencing safety functions and capable of exchanging information with external systems. This covers machines connected via Ethernet, Wi-Fi, USB, cloud services, or any remote monitoring or maintenance tool. Simple machines with no external data connections generally fall outside the scope.
What is a Safety-Related Security Level (SRSL)? The SRSL is a metric introduced by prEN 50742 to determine how much cybersecurity protection a specific safety function requires. It ranges from SRSL 0 (no protection needed for fully isolated systems) to SRSL 3 (maximum protection for machines with internet-facing or cloud connections). The SRSL is determined by combining the machine’s Exposure Level — how accessible it is to outside actors — with the potential impact of a successful attack on safety functions.
How does prEN 50742 relate to the Cyber Resilience Act? The CRA applies to all products with digital elements placed on the EU market and focuses on product cybersecurity in general. prEN 50742 is machine-specific and bridges general cybersecurity requirements with functional safety obligations under the Machinery Regulation. A machine that complies with prEN 50742 satisfies both the CRA requirements and the specific safety mandates of the Machinery Regulation, but the two frameworks approach the problem from different angles and should be assessed together, not as alternatives.
What is the difference between prEN 50742 and IEC 62443? IEC 62443 is an international standard series for industrial automation and control system security, widely used in manufacturing and process industries. prEN 50742 is a European harmonized standard specifically for machinery and directly supports compliance with the EU Machinery Regulation. prEN 50742 offers two implementation paths: one based on traditional safety risk assessment principles (suited to smaller manufacturers), and one that maps directly to IEC 62443 requirements (suited to organizations that already use it). The two are designed to be compatible, not competing.
Can I use IEC 62443 instead of prEN 50742 for Machinery Regulation compliance? prEN 50742 is the harmonized standard that provides presumption of conformity with Annex III, Section 1.1.9 of the Machinery Regulation. IEC 62443 can be used as part of the implementation path within prEN 50742, but using IEC 62443 alone does not automatically provide presumption of conformity with the Machinery Regulation. Manufacturers using IEC 62443 should verify that their implementation covers all the specific requirements of prEN 50742 before claiming conformity.
