CCyber Blog

Content on cybersecurity for industrial systems, OT, SCADA, PLC, DCS, critical infrastructure, manufacturing, energy, water utilities, transport and healthcare. We explain OT risk assessment, IEC 62443, segmentation, secure remote access, monitoring, incident readiness and the difference between IT and OT security priorities.

OT Security in 2026: Risk Assessment for PLC, DCS and SCADA

OT security protects not only systems but also the physical processes they operate. This guide explains PLC, DCS and SCADA roles and shows how to assess risk using IEC 62443 zones and conduits. It covers maintenance access, malware protection, recovery and evidence that safeguards work. It distinguishes NIS2 and Poland’s KSC obligations from DORA’s scope, and the potential of AI and digital twins from promises of automatic protection. An illustrative scenario connects a threat with a requirement and a safe verification method.

Prepared by: CCyber Editorial Team

Answer at a glance

OT security matters because compromise of an industrial system can affect a physical process: water pumping, production, temperature, pressure or service availability. Protection needs to address devices, software, communication and how they are operated.

A sound risk assessment starts with the process and potential consequences, not a tool purchase. Identify assets and connections, establish security zones, select safeguards and verify them without endangering production. The outcome should be an action plan with owners and evidence of completion.

Last updated

20 September 2026

This article develops the supplied notes on OT security, risk assessment, evidence and PLC, DCS and SCADA systems. Definitions and requirements were checked against NIST, IEC, cybersecurity authority guidance and legislation. The scenario, acceptance criteria and proposed working method are CCyber recommendations.

Technologies mentioned in the notes, including AI, digital twins and automated simulations, are treated as possible supporting capabilities. We do not assume they are universally deployed or mandatory in every OT environment.

Who this article is for

Industrial company boards, plant managers, control engineers, maintenance teams, IT and security teams, and integrators. It also supports infrastructure service operators preparing a risk assessment, modernization project or compliance review.

Key takeaways

  • A safe process matters more than availability at any cost. The integrity of measurements and commands can be as important as uninterrupted operation.
  • An OT risk assessment is not merely a vulnerability scan. It must address the physical process, dependencies and consequences of changes.
  • Evidence should demonstrate operation within a defined scope. A product certificate, network diagram and test result answer different questions.

Why is OT security particularly relevant in 2026?

Connecting plants with analytics services, cloud platforms and remote maintenance creates additional dependencies. This does not automatically make an architecture insecure, but requires decisions about which data and commands can cross between environments. This approach is developed in the international secure OT connectivity principles published in January 2026.

The risk is not merely a forecast. In an announcement dated 30 July 2026, the FBI and EPA described attacks on internet-facing PLCs in the US water and wastewater sector. Configuration changes caused loss of visibility or control functions. This is a documented US example, not a measure of incident frequency in Poland.

Missing risk documentation does not itself cause a breach. However, an inadequate assessment can leave an access path, excessive permissions or recovery gap unidentified. The assessment should therefore lead to technical and operational decisions.

Security and safety: the process does not have to run at any cost

Security concerns protection against compromise and unauthorized activity. Safety concerns protecting people, the environment and equipment from hazardous process consequences. The disciplines need to work together, but are not interchangeable.

The international OT cybersecurity principles put safety first. NIST also emphasizes distinct safety, reliability and performance requirements in its OT Security guide.

Do not adopt a fixed rule that IT cares about confidentiality while OT cares only about availability. A running system reporting incorrect measurements can be dangerous. Engineering information also requires confidentiality.

Our proposed assessment asks: when may operation continue, when is a contingency mode needed and who authorizes a controlled shutdown? Answers must come from people who understand the process and its protections.

PLC, DCS and SCADA: what are we protecting?

PLC: the controller executing process logic

A Programmable Logic Controller, or PLC, performs programmed control functions using inputs and defined logic. It can support a machine, part of an installation or a more complex process. It is not limited to basic on/off operations. Functions are described by NIST.

Security question: who can change the program, configuration and controller behaviour, and how would an unauthorized change be detected?

DCS: distributed process control

A Distributed Control System, or DCS, distributes control functions across components associated with the process rather than placing all control in one central unit. See the NIST definition.

A DCS can integrate control, visualization and engineering tools. Its name alone does not guarantee redundancy or the absence of single points of failure. Those are properties of the actual implementation.

Security question: could compromise of a shared engineering workstation or management service affect several parts of the process?

SCADA: supervision, data collection and supervisory control

Supervisory Control and Data Acquisition, or SCADA, collects and processes information while enabling supervision and higher-level control. It is also used for geographically distributed assets. It need not be one central application and is not limited to business reporting. See the NIST definition.

Security question: does the operator see a trustworthy process state, and can only authorized people issue commands?

A PLC is a control device, while DCS and SCADA describe broader systems. They can work together. Include operator interfaces, or HMIs, engineering workstations, historians and communication equipment in the assessment.

OT risk assessment: six stages

The following method is a CCyber recommendation. It connects the physical process with architecture, risk and safeguard verification.

1. Establish the process, scope and disruption consequences

Start with a service or process, such as water treatment or a selected production line. Identify assessment boundaries, the owner, dependencies and acceptable operating conditions.

Consider consequences for people, the environment, product quality and continuity of supply separately. Do not reduce every consequence to an hourly downtime cost. Record the effects that cannot yet be assessed.

2. Identify assets and actual connections

Combine engineering documentation, configurations and operator knowledge with traffic observation. Include service modems, integrator devices, removable media and external service connections.

The guidance on maintaining an accurate OT architecture view recommends multiple information sources. It also warns that active scanning can overwhelm older devices. Select and validate the method before using it.

Output: a verified asset and dependency map with unknown areas identified. An absence of traffic during a short observation should not be the sole reason for removing a connection.

3. Define zones and conduits

A zone groups assets with common security requirements. A conduit groups communications between zones for which shared security requirements are defined.

IEC 62443-3-2 covers defining the system under consideration, partitioning it into zones and conduits, assessing risk and establishing target security levels, or SL-T. Selecting a target does not demonstrate that it has been achieved.

In our proposed model: separate office systems, maintenance access and control areas according to process requirements. Record the purpose, direction, ownership and permitted communication for each connection. A diagram or VLAN name alone does not demonstrate effective separation.

4. Describe scenarios and assess risk

Consider scenarios such as a compromised supplier account, an unauthorized configuration change, loss of trustworthy measurements and ransomware affecting a workstation needed to operate the process.

For each scenario, identify required access, weaknesses, existing safeguards and consequences. Do not assume that shutting down a plant requires encrypting the PLC itself. A scenario may involve unavailable supervisory systems or business dependencies instead.

Output: a reasoned priority rather than only a scanner score. Mark missing information as uncertainty, not low risk.

5. Select safeguards and plan changes

Choose actions that address the scenario: access restriction, segmentation, configuration protection, better monitoring or improved recovery. Assign an owner, deadline and verification method.

Where an update requires a maintenance window, include compatibility testing and rollback arrangements. If remediation cannot occur immediately, define interim protection and a reassessment date. “It cannot be patched” should not end the assessment.

6. Verify the result and maintain the assessment

Check that the safeguard operates and has not impaired process conditions. The risk owner should understand remaining limitations.

Reassess after significant changes, such as a new IIoT gateway, integrator access, PLC modernization or altered recovery arrangements. Periodic reviews complement these triggers rather than replacing them.

Which safeguards should be implemented, and how can their operation be demonstrated?

Controlled connections and remote maintenance

The secure OT connectivity principles recommend brokered access through a controlled gateway rather than direct external access to control assets. They also describe restricting functions and communication between zones.

Proposed evidence: an approved connection register, access-control configuration and an agreed technician-access test. Include denial of out-of-scope access and session termination.

The remote OT access guide in the OT, Industrial and Critical Infrastructure Security category explores these arrangements further.

Malware protection and controlled file transfer

Do not assume that a standard endpoint agent can be installed on every PLC or real-time system. Selection requires checking support, operational impact and maintenance conditions.

Proposed action: define the approved route for project files and updates, removable-media controls and verification of file origin and integrity.

Proposed evidence: platform compatibility, a test result and documented exceptions. An antivirus invoice does not demonstrate protection across the entire OT environment.

Monitoring and response to unwanted changes

Agree which changes matter: a new connection, supplier access outside a maintenance window, project modification or communication loss. Identify who distinguishes scheduled maintenance from activity requiring a response.

Proposed evidence: a controlled alerting test with confirmation that the right person received it. A new IP address is not automatically an attack, but should be assessed against process and change information.

Configuration backups and process recovery

Recovery planning should cover more than office files. Include the appropriate controller projects, configurations, software versions and required engineering environment.

Proposed evidence: restoration in an agreed environment, with control engineers verifying configuration and required functions. Process restart should follow an approved commissioning or recovery procedure, not merely a “restore completed” message.

Example risk record: unauthorized setpoint changes

Illustrative CCyber scenario, not a real incident. A water treatment facility permits remote maintenance through an engineering workstation. The assessment investigates whether compromise of the maintenance account could allow unauthorized process changes.

Scenario: an unauthorized person uses maintenance access to perform an operation outside the approved task.

Potential consequence: loss of trustworthy control, a need to stop part of the process or a threat to water quality. The assessment must consider actual interlocks, alarms and independent measurements. We do not assume that every compromised account automatically results in contaminated water.

Requirement: access is restricted to agreed activities, changes need appropriate authorization and unwanted operations can be detected and addressed.

Verification: permission testing in a laboratory or another safely agreed scope, combined with an operator decision exercise. Do not deliberately alter the parameters of an operating treatment process.

Evidence: configuration version, test scope, result, action owner and remaining limitations. Testing one route does not constitute an assessment of the entire facility.

AI, digital twins and BAS: where do they help, and where are they insufficient?

AI: analytical support, not automatic authority to control

AI can support data analysis and anomaly detection, but integration also introduces risk. The joint principles for secure AI integration in OT address testing, oversight and safe failure arrangements.

Our recommendation: before automating connection blocking or device behaviour changes, test the consequences of false alarms and missing data. Response automation should not silently take over process safety decisions.

Digital twins: the model needs validation

NIST described research combining a digital process model, machine learning and expert knowledge to detect attacks on a laboratory 3D printer. This demonstrates a research capability, not comprehensive protection for any industrial installation.

Our recommendation: check how accurately the model represents the device, which phenomena it reproduces and its limitations. Do not automatically extrapolate a simulation result to the production process.

BAS: simulation also requires risk assessment

Breach and Attack Simulation means simulating selected attacker activities to test protection. This article does not assume that BAS is mandatory for every OT assessment.

Our recommendation: begin in a laboratory with an agreed scope. Production testing requires process-owner authorization, impact assessment, stopping conditions and recovery arrangements. Do not run a standard IT testing profile against controllers without this preparation.

ISO 27001, IEC 62443, NIS2 and DORA: what does an audit actually establish?

ISO/IEC 27001: evidence of ISMS and control operation

In ISO/IEC 27001:2022 Annex A, malware protection is referenced as A.8.7, while information transfer is A.5.14. Backups fall under A.8.13. Implementation guidance is developed in ISO/IEC 27002:2022, whose structure is visible in the public SIST preview.

A maintenance-file review can support assessment of these controls. It is not a certificate of PLC or plant security. The ISMS scope and Statement of Applicability matter.

IEC 62443: the right part and the right scope

IEC 62443-3-2 supports risk assessment during system design, while IEC 62443-3-3 specifies technical system security requirements and capability levels.

When commissioning work, identify the relevant part, system and criteria. A certified component does not automatically establish a secure integration. Zone diagrams should connect with requirements, configurations and verification.

NIS2 and KSC: organizational and management duties

Article 20 of NIS2 addresses management-body approval and oversight of cybersecurity risk-management measures. In Poland, Articles 8c-8d of KSC establish the manager’s accountability and duties. This is not an automatic penalty for every imperfect assessment or incident. The relevant obligation and grounds for liability must be established. See NIS2 and KSC.

Operating a PLC does not itself determine KSC applicability. For entities covered by the relevant transition period, important dates include self-registration by 3 October 2026 and implementation by 3 April 2027. Check organizational status and the official timetable.

DORA: not a general regulation for all industry

DORA concerns the digital resilience of specified financial entities and includes requirements concerning ICT providers. Its scope is explained by ESMA.

It does not automatically apply to a water utility or manufacturing plant simply because their services are economically important. A DORA requirement in an OT engagement needs a specific role, service or obligation behind it, rather than being added to every critical-infrastructure audit.

What should a useful evidence package look like?

We recommend linking process → risk scenario → requirement → safeguard → verification result → residual risk decision.

Each item should identify its scope, date, configuration version and owner. Retain failed tests and how findings were addressed. Do not present a new configuration as if it had been operating for months.

Distinguish readiness reviews, technical tests, audits against agreed criteria and certification. The label “OT audit” does not by itself establish what was examined or which conclusions can be drawn.

Where should a plant begin?

First: select one important process and bring together control engineering, maintenance, IT, security and the business owner. Agree the boundaries and safe working conditions.

Second: review the connection map, remote maintenance and configuration recovery. Address known serious threats promptly in coordination with operations rather than waiting for all documentation to be completed.

Third: approve priorities and deadlines. Report planned, implemented and verified safeguards separately. Do not measure improvement solely through the number of sensors installed.

Related CCyber resources and services

Remote maintenance and segmentation are explored in the OT, Industrial and Critical Infrastructure Security category. Exercise planning can also draw on incident response and business continuity resources. These links lead to Polish-language material.

This article focuses on process risk assessment and evidence. Detailed network design and safeguard selection require assessment of the actual installation.

How can CCyber help?

Through its cybersecurity project and implementation services, CCyber supports IT and OT risk assessment, segmentation, access control and audit preparation.

Start with a process whose loss would have the greatest impact on the organization. Prepare the installation description, available diagrams, supplier list and known limitations. The objective is an agreed protection plan and evidence, without testing that endangers people or production. Share technical information only after agreeing a secure channel.

FAQ

Is OT secure if it has no direct internet connection?

That cannot be determined from internet connectivity alone. Review maintenance access, IT connections, supplier devices and file transfer as well. Claimed isolation must reflect the actual architecture.

Is a vulnerability scan sufficient as an OT risk assessment?

No. It can provide some information, but does not independently establish process consequences, human safety implications or recovery arrangements. The scanning method also needs an OT impact assessment.

Should every PLC have antivirus and MFA?

Do not copy an office-computer configuration onto every controller. Select mechanisms according to the platform and risk. Strong authentication may be enforced through a controlled administrative path, with device protection supported by communication and change restrictions.

Can AI automatically disconnect suspicious devices?

Technical capability is not operational authorization. Before such automation, assess the consequences of disconnection, misclassification and missing inputs. The rules must account for safe process behaviour.

Does a small plant also need OT risk assessment?

The scope should reflect the process and possible consequences. A small device count does not imply that control functions are unimportant. Start with a bounded review without presenting it as an assessment of the entire organization.

Summary

OT security in 2026 requires an understanding of the process, architecture and threats. PLC, DCS and SCADA perform different functions and should not receive one uniform set of safeguards without considering their use.

A useful risk assessment ends with a verifiable decision: what is protected, against which scenario, who owns the action and how the outcome will be checked without endangering the process. AI and new tools can support this work, but do not replace it.

Sources

Secure Remote Access to OT: Common Mistakes and Good Practices

Secure remote access to OT is not just enabling a VPN, RDP or a supplier tool. In an industrial environment, remote access must be justified, temporary, controlled, monitored and possible to disconnect immediately. The most common mistakes are permanent supplier access, no MFA, shared accounts, direct internet access to HMI, PLC or engineering stations, no segmentation, no logs, no approval procedure and no emergency access cutoff test. Good practice means access through an intermediate zone, jump server, MFA, named accounts, least privilege, operational approval, maintenance window, session recording, full logging and regular access review.

Prepared by: CCyber Editorial Team

Short answer

Secure remote access to OT should be a controlled exception managed by process, not a permanent backdoor into the plant. The company should know who connects to the OT environment, why, for how long, from which device, through which channel, to which system and who approved the session. The greatest risks appear when suppliers have permanent VPN, RDP is exposed to the internet, accounts are shared, MFA is missing, access leads directly to HMI, PLC or engineering workstation, and nobody monitors sessions. Good practice is a model with no direct internet access to OT, IT and OT segmentation, intermediate zone, jump server, MFA, named accounts, time-bound access, approval by the process owner, logging, session recording and the ability to quickly disconnect remote access without stopping production.

Last updated

July 2026

Who this article is for

  • boards of manufacturing and industrial companies
  • plant directors, maintenance, automation and process engineers
  • CISOs, vCISOs, CTOs, CIOs and IT directors
  • people responsible for OT, SCADA, PLC, DCS, MES, BMS and industrial systems
  • automation integrators, service providers and industrial system suppliers
  • energy, water, logistics, chemical, food and manufacturing companies
  • organizations preparing for NIS2, IEC 62443, ISO 27001, customer audits or cyber insurance
  • SMEs that provide remote access to machine, production line or OT system vendors

Key takeaways

  1. Remote access to OT should be granted only when justified by a business or service need.
  2. Permanent, broad and uncontrolled supplier access to the OT network is one of the most dangerous mistakes.
  3. A VPN is not automatically secure. MFA, segmentation, scope limitation, logging and session control matter.
  4. RDP, VNC, TeamViewer, AnyDesk, modems, LTE routers and machine vendor tools must be covered by one register and one procedure.
  5. The best model is access through an intermediate zone, jump server, named accounts, maintenance window, OT owner approval and full activity record.

What is remote access to OT?

Remote access to OT means the ability to connect from outside the local industrial zone to systems that support production, automation, process technology, technical infrastructure or site safety. It may be used by an employee, IT provider, automation integrator, machine vendor, service technician, SOC operator or engineer working from another location.

Remote access may lead to:

  • engineering workstation
  • HMI
  • SCADA
  • DCS
  • MES system
  • data historian
  • PLC or controller
  • BMS system
  • OT application server
  • supplier service computer
  • industrial router or remote access gateway
  • machine monitoring or diagnostics system

The problem is that remote access can be both useful and risky. It enables service, diagnostics, supplier support, faster fault removal and work across many locations. But if poorly designed, it becomes the shortest path to systems that can stop production or affect human safety.

Why is remote access to OT riskier than typical IT access?

In IT, an incident may cause data loss, system downtime, information disclosure or ransomware. In OT, it may also stop a line, damage a machine, change a process parameter, reduce visibility, reduce control, threaten product quality or create safety risk.

OT has different priorities

  • process continuity is often more important than quick updating
  • systems may run for many years without major changes
  • some devices do not support modern MFA or logging
  • service downtime may require production planning
  • a configuration error may have physical consequences
  • some vendors require access to their own machines or controllers

This is why OT cannot simply copy office IT rules. Remote access must be designed with automation, maintenance, IT, security, production and technology vendors.

Typical use cases for remote access to OT

Machine vendor service

The machine vendor connects to check alarms, parameters, configuration, drive errors, logs or software version.

Automation integrator support

The integrator connects to SCADA, PLC, HMI or engineering workstation to perform a change, diagnostics or fix.

Remote maintenance diagnostics

A plant engineer or central technical team connects from multiple locations to analyze installation status.

Production and process data monitoring

Data from historian, MES, BMS or monitoring systems is reviewed remotely by selected people or analytics systems.

After-hours failure

The service team needs urgent access at night, over the weekend or during production downtime.

Security provider access

SOC, MDR or OT monitoring provider needs access to logs, sensors, consoles or telemetry data.

Common mistakes in remote access to OT

Mistake 1: permanent supplier access without control

The most common issue is access that was once enabled for service and never turned off. The supplier has an account, VPN, LTE router or remote desktop tool, and the plant does not know when or why someone connects.

Risk

  • attacker takes over supplier account
  • supplier has broader access than needed
  • no visibility of active sessions
  • no evidence of actions after an incident
  • difficult access shutdown during crisis

Good practice

  • access only for service duration
  • approval by OT owner
  • named account
  • MFA
  • scope limited to a specific system
  • logging and session recording

Mistake 2: direct internet access to HMI, PLC, SCADA or engineering workstation

Directly exposing an OT system to the internet is very high risk. Even if access is password-protected, this setup increases attack surface.

Risk

  • internet scanning
  • brute force
  • vulnerability exploitation
  • access without plant visibility
  • attack on a device that cannot be quickly patched

Good practice

  • no direct internet access to OT
  • access through VPN or ZTNA to an intermediate zone
  • jump server in DMZ
  • firewall rules only to required systems
  • connection monitoring

Mistake 3: RDP or VNC as the default service path

RDP, VNC and remote desktop tools are convenient, but in OT they may provide too much access. If a user gets the engineering workstation desktop, they can do much more than diagnostics.

Risk

  • full system access instead of one function
  • configuration changes
  • project file copying
  • running unapproved tools
  • no control over user commands

Good practice

  • access through jump server
  • file copy disabled if not needed
  • session recording
  • separate service accounts
  • approval of every session
  • ability to disconnect immediately

Mistake 4: no MFA

A password is not enough. In supplier and service environments, passwords may be shared, used by multiple people or stored insecurely. Without MFA, password compromise may mean entry into OT.

Risk

  • supplier account takeover
  • credential stuffing
  • old password use
  • former supplier employee access
  • no second protection layer

Good practice

  • MFA for VPN, jump server and access portal
  • MFA for supplier accounts
  • no shared service accounts where avoidable
  • separate emergency account policy
  • regular exception review

Mistake 5: shared supplier accounts

An account named “service”, “vendor”, “automation” or “support” is convenient, but destroys accountability. After an incident, the company does not know who made the change.

Risk

  • no individual accountability
  • no knowledge who connected
  • password passed between people
  • no quick removal of access for one person
  • audit problem

Good practice

  • named accounts
  • separate accounts for supplier and plant employees
  • regular account review
  • account blocking after cooperation ends
  • activity logging by user

Mistake 6: access to the whole OT network instead of a specific target

VPN often grants access to an entire subnet. In OT, this is too broad. A technician servicing one machine should not see the whole production network.

Risk

  • lateral movement
  • OT network scanning
  • access to unrelated machines
  • attack on legacy devices
  • difficult incident scope analysis

Good practice

  • access to a specific host or application
  • firewall rules between zones
  • segmentation by line, process, criticality or supplier
  • no routing to the whole OT network
  • least privilege

Mistake 7: no intermediate zone

A remote user should not land directly in control systems. An intermediate zone, DMZ or jump server reduces risk and provides a place for logging, control, scanning and policy enforcement.

Risk

  • direct connection to critical system
  • no control point
  • no session recording
  • no IT and OT separation
  • easier pivoting into control systems

Good practice

  • DMZ between IT and OT
  • jump server in intermediate zone
  • no direct tunnel to PLC
  • traffic monitoring between zones
  • rules only for explicitly approved flows

Mistake 8: no remote access tool register

Many plants have different remote access channels: IT VPN, machine vendor router, 4G modem, service laptop, TeamViewer, AnyDesk, supplier cloud portal and diagnostic tunnel. Without a register, nobody sees the full risk.

Risk

  • hidden OT entry points
  • no access owner
  • no update of supplier tool
  • no visibility of active connections
  • audit and incident problems

Good practice

  • one OT remote access register
  • owner for each channel
  • date of last use
  • access scope
  • MFA status
  • decision to keep, reduce or remove

Mistake 9: no logs and session recording

If someone makes a change in OT, the company should know who, when, from which address, to which system and what was done. Without logs, there is no accountability.

Risk

  • no incident timeline
  • no evidence of supplier actions
  • difficult change analysis
  • problem during complaint or dispute
  • lack of data for SOC or audit

Good practice

  • logging logins and disconnections
  • logging administrative commands
  • session recording for high-risk actions
  • central log storage outside the OT station
  • regular review of unusual sessions

Mistake 10: no emergency remote access cutoff

During an incident, the plant must be able to quickly block remote access. This cannot require hours of searching for an administrator, supplier or router password.

Risk

  • attacker keeps access
  • loss of control during crisis
  • disconnection affects the process unpredictably
  • operators do not know what to disable
  • delayed isolation

Good practice

  • documented disable remote access procedure
  • access cutoff test
  • named owner and deputy
  • production impact assessment
  • operator and maintenance training

Good remote access model for OT

Layer 1: business decision

Every remote access channel should have a justification. The question is not “can we connect?”, but “do we really need this access and what business problem does it solve?”.

Layer 2: architecture

Access should go through a controlled intermediate zone. A remote user should not connect directly to PLC, HMI or engineering workstation.

Layer 3: identity

Every person should have a named account, MFA and assigned role. Supplier accounts should be separated from plant employee accounts.

Layer 4: scope

Access should be limited to a specific machine, system, application or zone. Not the entire OT network.

Layer 5: time

Access should be active only during an approved maintenance window. After work ends, it should be disabled.

Layer 6: observability

The company should have logs, alerts and, for high-risk actions, session recording.

Layer 7: emergency cutoff

The plant should be able to disconnect remote access without chaos, without stopping unnecessary systems and without creating human safety risk.

Good practice list

1. Build an OT remote access register

  • access channel name
  • supplier or user
  • target system
  • permission scope
  • connection technology
  • whether MFA is enabled
  • whether the session is logged
  • whether access is permanent or time-bound
  • business owner
  • date of last review

2. Remove direct internet access

HMI, PLC, SCADA, engineering workstations and industrial routers should not be directly accessible from the internet. Any such exposure requires urgent analysis and usually removal.

3. Require MFA for all remote access points

MFA should cover VPN, jump server, access portal, supplier accounts and administrator access. Exceptions should be documented and accepted by the risk owner.

4. Use jump server or bastion

A jump server helps limit access, log sessions, record actions and separate the remote user from direct access to industrial systems.

5. Divide the network into zones

Segment OT by function, line, process, location or criticality. Supplier access to one machine should not open a path to the entire plant.

6. Limit protocols and ports

Allow only communication needed for the specific work. Block unnecessary RDP, VNC, SSH, SMB, FTP, web management and other services.

7. Define session approval process

Every service session should have a request, owner, purpose, time, scope and completion confirmation. For high-risk actions, require maintenance or production approval.

8. Define maintenance windows

Not every task can be done at any time. OT changes should be agreed with production and assessed for process safety impact.

9. Log and record sessions

Logs should include user, time, source, target, session duration, protocol used and actions performed. Supplier and engineering workstation sessions should be recorded for high-risk access.

10. Test the access cutoff procedure

At least once a year, check whether the company can quickly disable supplier remote access, VPN or industrial router. The test should not endanger production.

11. Agree requirements with suppliers

Supplier contracts should describe MFA, named accounts, access scope, logging, incident reporting, subcontractors, remote tool updates and audit rights.

12. Monitor access outside working hours

Night, weekend, long, unusual location or unusual target sessions should generate an alert.

13. Do not use private devices for OT

A device used to access OT should be managed, updated, protected, malware-free and compliant with company requirements. A supplier’s private laptop should not freely access OT without control.

14. Separate diagnostics from control

If the supplier only needs to read alarms or data, do not grant write, program change or parameter modification rights.

15. Perform regular access review

At least quarterly, check who has remote access to OT. Remove former employees, former technicians, inactive suppliers and old tunnels.

Target model: what should the connection look like?

Example safer flow

  1. The supplier requests service access.
  2. The OT owner approves purpose, time and scope.
  3. The supplier logs in to the access portal with MFA.
  4. Access is activated only for the maintenance window.
  5. The supplier lands on a jump server in the intermediate zone.
  6. From the jump server, the supplier can connect only to the approved system.
  7. The session is logged and recorded.
  8. An operator or automation engineer supervises high-risk actions.
  9. Access is disabled after work is completed.
  10. The request is closed with a description of actions performed.

What does this provide?

  • the company knows who connects
  • the company knows why they connect
  • scope is limited
  • time is limited
  • actions are documented
  • access can be cut off during an incident
  • production knows when the supplier is working

Checklist for the OT owner

  • do we know all remote access channels into OT?
  • does every channel have an owner?
  • does every access have business justification?
  • is access permanent or time-bound?
  • is MFA enabled?
  • are accounts named?
  • is access limited to a specific system?
  • are sessions logged?
  • are supplier actions recorded?
  • can access be disconnected quickly?
  • was the cutoff procedure tested?
  • are suppliers covered by security agreements?
  • was access review performed in the last quarter?
  • are remote changes entered into the change register?
  • does remote access avoid bypassing process safety rules?

Checklist for supplier or integrator

  • does every technician have a named account?
  • does the supplier enforce MFA?
  • does the supplier know who connected to the customer?
  • is access granted for a specific service duration?
  • does the supplier report security incidents to the customer?
  • does the supplier control subcontractors?
  • is the service device updated and protected?
  • does the supplier document completed changes?
  • does the supplier accept session recording?
  • does the supplier have a procedure to remove access for former employees?

What documents and evidence should be prepared?

Documents

  • OT remote access policy
  • service access approval procedure
  • emergency remote access cutoff procedure
  • MFA standard for OT access
  • jump server and intermediate zone standard
  • supplier access review procedure
  • remote change procedure
  • security requirements for OT suppliers

Registers

  • OT remote access register
  • supplier account register
  • remote access tool register
  • industrial router and modem register
  • MFA exception register
  • service session register
  • OT change register
  • incident and near miss register

Technical evidence

  • MFA report
  • active supplier account report
  • firewall rule report
  • VPN or ZTNA connection list
  • jump server logs
  • high-risk session recordings
  • access review report
  • remote access cutoff test report

30, 60 and 90-day action plan

First 30 days

  • assign remote access to OT owner
  • collect all remote access channels
  • identify suppliers with OT access
  • check whether direct internet access exists
  • check MFA on VPN, portal and supplier accounts
  • block unused accounts
  • prepare remote access register
  • present top risks to the board

Days 31 to 60

  • implement session approval process
  • limit access to specific systems
  • move supplier access through jump server
  • enable logging and recording of high-risk sessions
  • remove or reduce permanent supplier tunnels
  • review firewall rules between IT and OT
  • agree requirements with suppliers
  • prepare emergency cutoff procedure

Days 61 to 90

  • perform emergency access cutoff test
  • perform supplier access review
  • update contracts and SLA
  • train automation, IT and maintenance teams
  • run tabletop for remote access incident
  • close top gaps
  • prepare evidence pack for audit
  • define quarterly review cycle

Metrics for the board and plant director

Visibility metrics

  • number of identified remote access channels
  • number of channels without owner
  • number of suppliers with active access
  • number of remote access tools outside the standard

Control metrics

  • percentage of access channels with MFA
  • percentage of named accounts
  • percentage of time-bound access
  • number of shared accounts
  • number of permanent supplier tunnels

Monitoring metrics

  • percentage of sessions logged
  • percentage of high-risk sessions recorded
  • number of sessions outside maintenance windows
  • number of failed logins
  • number of unusual supplier sessions

Resilience metrics

  • date of latest access cutoff test
  • time to cut off remote access during exercise
  • number of OT systems with recovery priority
  • number of gaps closed after review

Incident scenario: attack through supplier remote access

An automation supplier has permanent VPN access to the plant network. One of its accounts is compromised. The attacker logs in in the evening, scans the OT network, finds an engineering workstation and attempts to download project files. Then errors appear on HMI and unusual connections to several controllers are observed.

What should work?

  • unusual login alert
  • MFA and bypass attempt detection
  • access limited only to the approved system
  • no ability to scan the entire OT network
  • logging and session recording
  • immediate supplier account cutoff
  • contact with supplier and OT owner
  • checking whether controller changes occurred
  • incident report and remediation actions

What often appears during exercises?

  • nobody knows who owns the supplier VPN
  • the account is shared
  • MFA is not enabled for the supplier
  • VPN gives access to the whole OT subnet
  • session logs are missing
  • nobody knows how quickly access can be cut off
  • the contract does not define supplier duties after an incident

Common mistakes in OT supplier contracts

No security requirements

The contract describes service, but does not describe MFA, named accounts, logs, session recording, incidents or subcontractors.

No audit rights

The plant cannot check whether the supplier manages accounts, service devices and subcontractors.

No incident reporting rules

The supplier may have an incident, but the customer may not learn about it in time.

No access removal procedure

After contract termination, the supplier account, router or tunnel still exists.

No subcontractor accountability

The supplier allows another company to perform remote service, but the plant does not know who actually has access.

How to prepare a remote access to OT audit?

Audit scope

  • all remote access channels
  • VPN, ZTNA, RDP, VNC, SSH and remote desktop tools
  • industrial routers, modems, LTE gateways and supplier devices
  • supplier and integrator access
  • identity control and MFA
  • logs and monitoring
  • firewall rules and segmentation
  • contracts and procedures
  • emergency access cutoff

Audit output

  • remote access map
  • risk list
  • quick shutdown list
  • access reduction list
  • recommended target architecture
  • 30, 60 and 90-day action plan
  • evidence pack for board and audit

Business example

A manufacturing company has 6 production lines. Each line has a different machine vendor. Over the years, vendors enabled their own remote access methods: one has VPN, another an LTE router, another TeamViewer on HMI and another a diagnostic modem. The plant knows that “vendors somehow connect”, but has no complete list.

The audit reveals 11 remote access channels, 4 permanent tunnels, 3 shared accounts, 2 tools without MFA and one router with no known owner. One supplier has access to the entire OT subnet even though it services only one machine.

The company introduces an access register, closes unused tunnels, moves suppliers through a jump server, enables MFA, defines maintenance windows and records high-risk sessions. After 90 days, remote access still works, but it is visible, controlled and can be disconnected. Production keeps supplier support and the board receives a real risk report.

How can ccyber.io help?

ccyber.io helps industrial companies organize and secure remote access to OT without paralyzing service and maintenance. We combine automation, IT, security, production, supplier and board perspectives.

We can support your organization with:

  • remote access to OT audit
  • remote access channel register
  • assessment of VPN, RDP, VNC, TeamViewer, AnyDesk, LTE routers and supplier tools
  • jump server, DMZ and segmentation architecture design
  • MFA and named accounts for suppliers
  • service session approval procedure
  • session logging and recording
  • emergency remote access cutoff procedure
  • security requirements for machine vendors and integrators
  • tabletop for remote access incident
  • 30, 60, 90-day and 12-month roadmap

The best first step is an OT Remote Access Readiness Workshop. In a short workshop, the company can determine who currently has OT access, which channels are most dangerous, what must be disabled immediately and what should be moved to a safer model.

FAQ

Is VPN enough for secure access to OT?

No. VPN may be part of the solution, but VPN alone is not enough. MFA, scope limitation, segmentation, logging, supplier control and access cutoff capability are needed.

Can a supplier have permanent access to a machine?

Permanent access should be an exception, well justified and controlled. A safer model is time-bound access activated for a maintenance window and approved by the OT owner.

Is RDP to an engineering workstation safe?

It can be very risky if available directly or without control. Use a jump server, MFA, named accounts, session recording and function restrictions.

Can a machine vendor use its own LTE router?

It can, but only if it is registered, approved, configured according to security requirements, covered by MFA, logging and cutoff procedure.

How often should remote access to OT be reviewed?

At least quarterly and after every change of supplier, production line, system, integrator or incident.

Who should approve remote access to OT?

The owner of the OT process or system, usually maintenance, automation or production, in cooperation with IT and security.

Should supplier sessions be recorded?

For high-risk actions, yes. Recordings support accountability, change analysis, audits and incident investigation.

Where should we start?

Start with a register: who has remote access to OT, how they connect, what they can access, whether MFA is enabled, whether the session is logged and who owns the access.

Summary

Secure remote access to OT is needed, but it must be controlled. The greatest risk is not remote access itself, but lack of visibility, no MFA, permanent tunnels, shared accounts, direct access to OT systems and no cutoff procedure.

A good architecture is based on segmentation, intermediate zone, jump server, named accounts, MFA, time-bound access, logging, session recording and regular access review.

The best rule is: remote access to OT should be treated like service work inside the plant. It must have purpose, approval, time, scope, supervision, activity record and safe completion.

Sources

IEC 62443 in Practice: Zones, Conduits and OT Network Segmentation

IEC 62443 helps organize OT security by dividing the environment into zones and communication conduits. A zone groups assets with similar risk and security requirements, while a conduit describes controlled communication between zones. In practice, this is not only about VLANs and firewalls, but about understanding processes, dependencies, risk, remote access, data flows, accountability and secure IT/OT communication rules.

Prepared by: CCyber Editorial Team

Short answer

IEC 62443 in practice helps design OT security by dividing a plant, lines, systems and connections into zones and communication conduits. A zone is a group of assets with similar function, risk and security requirements, for example a production line, SCADA system, engineering workstations, process safety network or industrial DMZ. A conduit is a controlled communication path between zones, for example MES to SCADA, historian to DMZ, remote vendor to jump server or SCADA to PLC. OT network segmentation is not only about VLANs. It is a business and technical process: asset inventory, communication mapping, risk analysis, boundary definition, traffic limitation, monitoring, change management and testing.

Last updated

July 2026

Who this article is for

  • manufacturing boards
  • plant managers and operations directors
  • production, maintenance and quality managers
  • CISOs, vCISOs, CTOs, IT directors and OT security managers
  • automation engineers, OT engineers, integrators and SCADA, PLC, DCS, MES teams
  • manufacturing, energy, transport, water, chemical, food, pharmaceutical and automotive companies
  • critical infrastructure operators and organizations affected by NIS2 or KSC requirements
  • organizations preparing for IEC 62443, ISO 27001, cyber insurance or customer audits
  • companies that want to organize IT/OT segmentation and supplier remote access

Key takeaways

  1. IEC 62443 does not start with a firewall. It starts with understanding processes, assets, risk, communication and the consequences of failure in OT.
  2. A zone groups assets with similar security requirements, while a conduit describes controlled communication between zones.
  3. OT segmentation should limit incident impact, lateral movement, uncontrolled supplier access and accidental connections between IT and control systems.
  4. A VLAN is not full segmentation. Traffic rules, firewalls, allowlists, monitoring, logs, zone owners and change procedures are needed.
  5. A strong segmentation project ends with documents and evidence: zone map, conduit matrix, flow list, firewall rules, exceptions, tests and maintenance plan.

What is IEC 62443?

IEC 62443 is a series of standards for cybersecurity of industrial automation and control systems. In practice, it is used to organize security of OT, ICS, SCADA, PLC, DCS, HMI, MES, engineering workstations, historians, industrial networks and supplier remote access.

IEC 62443 is especially useful because it does not treat OT like a normal office network. It considers:

  • human safety
  • process continuity
  • line availability
  • control reliability
  • physical safety
  • legacy system limitations
  • suppliers and integrators
  • industrial system lifecycle
  • different roles: asset owner, integrator, service provider and component manufacturer

For this article, the key practical concepts are: zones, conduits, security levels, risk and segmentation.

What is a zone in IEC 62443?

A zone is a group of assets with similar function, risk and security requirements. A zone may be a physical part of the plant, a logical network area, a system group or a process function.

Examples of zones:

  • enterprise IT network
  • industrial DMZ
  • MES system
  • SCADA system
  • engineering workstations
  • packaging line
  • critical production line
  • PLC for a specific process
  • process safety network
  • historian system
  • supplier remote access
  • OT test laboratory

The key rule: zones are not defined only by IP addressing. A zone should follow risk, process function, criticality, ownership, trust level and incident impact.

What is a conduit in IEC 62443?

A conduit is a controlled communication path between zones. It describes which systems can communicate, using which protocol, in which direction, for what purpose, through which control point and under which conditions.

Examples of conduits:

  • ERP to MES
  • MES to SCADA
  • SCADA to PLC
  • historian to industrial DMZ
  • engineering workstation to PLC
  • remote supplier to jump server
  • update server to OT workstation
  • backup system to OT server
  • monitoring system to TAP or SPAN
  • quality system to production data

A conduit should have an owner and rules. Without that, the company does not know whether a given traffic flow is needed, safe and aligned with the process.

Zone, conduit and segmentation: simple distinction

Zone

Answers the question: which assets have similar security requirements and should be treated together?

Conduit

Answers the question: which communication between zones is needed and how do we control it?

Segmentation

Answers the question: how do we technically and organizationally separate zones and enforce communication rules?

Example: the SCADA network is a zone, SCADA to historian is a conduit, and segmentation is the firewall, allowlist, monitoring and rule that the historian cannot initiate traffic to PLCs.

Why is OT segmentation so important?

In OT, one uncontrolled access path can have greater consequences than in classic IT. An attacker may start from a normal office computer, move through an administrator account, reach an engineering workstation and then affect control, quality, availability or process safety.

Segmentation helps limit:

  • lateral movement from IT to OT
  • ransomware spread
  • uncontrolled supplier access
  • accidental scanning of OT networks
  • unauthorized connections to PLCs
  • office workstation access to control systems
  • infected service laptop risk
  • lack of visibility over data flows
  • uncontrolled cloud and IT integrations
  • outages caused by incorrect network changes

Segmentation does not guarantee complete security, but it strongly reduces the impact of errors, incidents or compromise of one account.

Why is a VLAN not enough?

A VLAN can be part of segmentation, but a VLAN alone is not enough. If there is no traffic control, monitoring, rules, owners and change process between VLANs, segmentation is only a logical network split, not a real security control.

A VLAN helps

  • separate traffic logically
  • reduce broadcast domain
  • organize addressing
  • simplify network management

A VLAN is not enough if

  • inter-VLAN traffic is open
  • there is no list of allowed connections
  • there is no firewall or boundary control
  • nobody knows who owns the zone
  • there are no logs
  • suppliers have standing access
  • engineering workstations can connect everywhere
  • changes are made without risk review

In practice, OT segmentation means combining architecture, traffic rules, access control, monitoring, procedures and accountability.

How to design zones and conduits step by step?

Step 1: inventory OT assets

You cannot design zones without knowing which assets exist. Inventory should include not only servers and computers, but also controllers, network devices, visualization systems, engineering workstations and remote access.

List:

  • PLC
  • DCS
  • SCADA
  • HMI
  • engineering workstations
  • historian servers
  • MES
  • WMS and warehouse systems
  • quality systems
  • network devices
  • firewalls
  • remote access points
  • service laptops
  • process safety systems
  • OT backup systems

Evidence to prepare: OT asset register with owner, location, function and criticality.

Step 2: understand the physical process

Segmentation cannot be designed only from the network perspective. You must know what happens in the physical process if communication is blocked, delayed or manipulated.

Ask:

  • which lines are critical?
  • which systems must operate in real time?
  • which data is needed for quality?
  • which connections are needed for safe shutdown?
  • which systems can operate offline?
  • which connections are convenient but not critical?
  • which systems affect human or environmental safety?

Evidence to prepare: map of processes, lines and operational dependencies.

Step 3: map communication flows

The most important segmentation document is the communication map. It shows who talks to whom, using which protocol, in which direction and for what purpose.

For every flow, record:

  • source system
  • destination system
  • protocol
  • port
  • direction
  • frequency
  • business or operational purpose
  • owner
  • criticality
  • whether the flow is required continuously, temporarily or only for service

Evidence to prepare: IT/OT communication flow matrix.

Step 4: group assets into zones

Group assets by function, risk and security requirements. Do not mix systems with completely different criticality in one zone only because they are in the same cabinet or subnet.

Zone design criteria

  • process function
  • production criticality
  • impact on human safety
  • asset type
  • availability requirements
  • trust level
  • patchability
  • system owner
  • supplier access need
  • impact of compromise

Evidence to prepare: zone list with justification and owners.

Step 5: define conduits between zones

After defining zones, specify which communication between them is allowed. The default rule should be: block everything that is not required and documented.

For each conduit, define:

  • which zones it connects
  • which traffic is allowed
  • which traffic is forbidden
  • who initiates the connection
  • whether traffic is one-way or two-way
  • whether authentication is required
  • whether time-bound approval is required
  • where traffic is logged
  • who owns the conduit

Evidence to prepare: conduit matrix between zones.

Step 6: assign security requirements

Zones should have security requirements based on risk. Not every zone needs the same level of protection. A process safety zone, engineering workstations and critical production controllers will usually need stronger controls than a reporting zone.

Requirements may include:

  • access control
  • authentication
  • account management
  • logging
  • monitoring
  • malware protection
  • configuration backup
  • change control
  • protocol restriction
  • remote access only through controlled path

Evidence to prepare: security requirements card for every zone.

Step 7: design technical segmentation

Only now is it time for technology. First process, assets, zones and conduits. Then firewalls, VLANs, routing, jump servers and monitoring.

Technical controls may include:

  • firewalls between zones
  • industrial DMZ
  • traffic allowlists
  • VLANs and subnets
  • ACLs on network devices
  • jump servers
  • VPN with MFA for suppliers
  • data diode or one-way communication where appropriate
  • passive IDS for OT
  • central logs
  • separation of test and production environments

Evidence to prepare: OT segmentation architecture design.

Step 8: test rules before deployment

In OT, a wrong firewall rule may stop a line or break communication with a critical system. Testing is mandatory.

The test should verify:

  • whether allowed traffic works
  • whether forbidden traffic is blocked
  • whether there is no delay affecting the process
  • whether alarm systems work
  • whether historian still collects data
  • whether the engineering workstation works only within allowed scope
  • whether supplier access works only through the approved path
  • whether logs are collected

Evidence to prepare: segmentation test report and exception list.

Step 9: implement change process

OT segmentation becomes outdated quickly if every outage, project or new line adds exceptions without control. Every conduit change should follow a process.

The process should include:

  • change request
  • business justification
  • risk assessment
  • zone owner
  • change validity period
  • test after change
  • documentation update
  • exception review

Evidence to prepare: change management procedure for OT zones and conduits.

Step 10: monitor and maintain segmentation

Segmentation is not a one-time project. Traffic must be monitored, rules reviewed, exceptions removed, maps updated and real traffic compared with documentation.

Minimum maintenance:

  • firewall rule review
  • conduit review
  • supplier access review
  • comparison of real traffic with communication matrix
  • new device monitoring
  • alerts for unusual communication
  • network map update
  • report for OT owners and the board

Evidence to prepare: recurring OT segmentation maintenance report.

Example zone model for a manufacturing plant

Zone 1: enterprise IT network

Includes email, office computers, user systems, internet, corporate applications and typical IT services. It should not have direct access to control systems.

Zone 2: industrial DMZ

A buffer between IT and OT. It can host data exchange systems, transfer servers, historian proxy, patch repository, jump server, monitoring and controlled integration points.

Zone 3: operations management

May include MES, production planning, reporting, quality systems and production integrations. This is often a boundary area between IT and OT.

Zone 4: supervisory control

Includes SCADA, HMI, OT application servers, internal historian and process supervision systems.

Zone 5: basic control

Includes PLCs, RTUs, controllers, industrial communication devices and systems directly involved in control.

Zone 6: safety and protection

Includes process safety systems, machine safety, SIS, ESD or other systems whose compromise may affect people, environment or installation. This zone requires especially careful separation.

Zone 7: vendor remote access

Includes controlled supplier access through MFA, VPN, jump server, session recording, time-bound approval and logging.

Zone 8: engineering and maintenance

Includes engineering workstations, PLC programming tools, SCADA configurations, project backups and maintenance environments. This is one of the riskiest zones because it enables changes in control systems.

Which conduits matter most?

ERP to MES conduit

Purpose: production plan, orders, materials, statuses.

Risk: ransomware or IT error may affect production planning.

Control: industrial DMZ, restricted protocols, data validation, no direct ERP connection to PLCs.

MES to SCADA conduit

Purpose: orders, production parameters, process status.

Risk: incorrect data may affect process or quality.

Control: flow allowlist, validation, logs, direction limitation.

SCADA to PLC conduit

Purpose: supervision, commands, status reading.

Risk: unauthorized commands or operating mode changes.

Control: zone separation, industrial protocol monitoring, limiting communication sources.

Historian to DMZ conduit

Purpose: transferring production data to reporting.

Risk: uncontrolled traffic from IT to OT.

Control: preferred direction from OT to DMZ, no initiation from IT to control systems, monitoring.

Supplier to service station conduit

Purpose: service, diagnostics, supplier support.

Risk: external access to OT environment.

Control: MFA, time-bound approval, jump server, session recording, no standing access.

Engineering workstation to PLC conduit

Purpose: programming, diagnostics, configuration changes.

Risk: program change, incorrect configuration, malware on workstation.

Control: dedicated workstation, change control, project backup, logging, access only for authorized people.

Which rules should apply at zone boundaries?

Default deny

Traffic between zones should be blocked unless it is explicitly allowed and justified.

Least communication privilege

Allow only the necessary source, destination, protocol, port and direction.

No owner, no traffic

Every conduit should have a business or technical owner.

Separate operational and service traffic

Remote access, updates, backup and engineering work should not mix with control traffic.

Limit IT to OT traffic

If data must pass between IT and OT, use DMZ, broker, intermediate server or another controlled mechanism.

Log boundary communication

Zone boundaries are natural monitoring points. Unusual traffic between zones should be visible.

Test every change

A rule change can stop a process. In OT, testing and maintenance windows are more important than fast emergency changes.

What documents and evidence should be prepared?

Architecture documents

  • IT/OT network map
  • zone list
  • conduit matrix
  • data flow diagram
  • zone boundary list
  • firewall and control point list
  • remote access list
  • IT/OT integration list

Risk documents

  • OT risk assessment
  • critical asset list
  • process impact analysis
  • incident scenarios
  • security requirements mapped to zones
  • exception and risk acceptance list

Technical evidence

  • firewall configurations
  • inter-zone rule list
  • zone boundary logs
  • segmentation test report
  • real traffic discovery report
  • supplier access report
  • network configuration backup report

Operational documents

  • firewall rule change procedure
  • supplier remote access procedure
  • IT/OT isolation procedure
  • emergency OT access procedure
  • zone owner list
  • emergency contact list

Common OT segmentation mistakes

Mistake 1: the project starts with VLANs

Addressing and VLANs matter, but they do not replace process, risk, zone and conduit analysis.

Mistake 2: one large production network

Many plants have one large OT network where SCADA, HMI, PLCs, engineering workstations and suppliers see too much. This increases incident impact.

Mistake 3: direct IT to OT connection

Direct connections from ERP, office laptops or reporting systems to OT create an easy attack path.

Mistake 4: no industrial DMZ

A DMZ is often the best place for controlled data exchange between IT and OT. Without it, integrations become random and hard to control.

Mistake 5: standing supplier access

A supplier should have access only when needed, through a controlled path and with logging.

Mistake 6: no communication matrix

If the company does not know which traffic is required, it cannot safely close unnecessary connections.

Mistake 7: no testing after changes

In OT, a rule change may have production impact. Every change must be tested and documented.

Mistake 8: no zone owners

If nobody owns a zone, nobody makes decisions about risk, changes and exceptions.

Mistake 9: segmentation without monitoring

Segmentation blocks some traffic, but monitoring shows whether someone is trying to cross zone boundaries and whether rules work.

Mistake 10: no documentation update

OT networks change with every project, modernization and service action. Documentation must live with the change process.

How to measure OT segmentation effectiveness?

Architecture metrics

  • number of defined zones
  • number of defined conduits
  • percentage of OT assets assigned to zones
  • number of conduits without owner
  • number of IT/OT connections without DMZ or control

Traffic metrics

  • number of allowed flows
  • number of detected undocumented flows
  • number of blocked communication attempts
  • number of high-risk protocols
  • number of expired temporary exceptions

Access metrics

  • number of active supplier accesses
  • number of accesses without MFA
  • number of standing remote accesses
  • number of engineering workstations with access to multiple zones
  • number of OT administrator accounts

Operational metrics

  • number of firewall rule changes per month
  • number of changes without full documentation
  • number of segmentation incidents
  • change approval time
  • date of latest IT/OT isolation test

30, 60 and 90-day action plan

First 30 days

  • assign owner for the zones and conduits project
  • identify critical systems and processes
  • prepare initial OT asset inventory
  • check existing IT/OT connections
  • check supplier remote access
  • collect existing network diagrams
  • identify the most important communication flows
  • define first high-risk zones

Days 31 to 60

  • prepare a more complete zone map
  • prepare conduit matrix
  • mark required, optional and suspicious flows
  • define zone boundaries
  • define security requirements for critical zones
  • prepare industrial DMZ design if missing
  • prepare supplier remote access rules
  • identify quick risk reduction actions

Days 61 to 90

  • implement first segmentation rules for high-risk zones
  • test rules with production and OT
  • enable monitoring at zone boundaries
  • prepare conduit change procedure
  • remove unused connections
  • reduce standing supplier access
  • prepare report for the board
  • plan full 12-month IEC 62443 roadmap

Business example

A manufacturing plant has one large OT network. SCADA, HMI, engineering workstations, historians, several production lines and supplier remote access operate in the same address space. IT connects to MES and reporting. Documentation is outdated and some system traffic has no owner.

During the first review, the company discovers that a supplier can connect to more than one line, an engineering workstation has access to many PLCs, the historian communicates directly with the office network and the reporting system queries OT sources without a DMZ.

The company does not start by replacing the whole network. First, it creates a map of assets, flows, zones and conduits. It separates the SCADA zone, engineering workstation zone, production line zones, industrial DMZ and supplier access zone. Then it defines conduits, limits traffic, introduces a jump server for suppliers, removes unused connections and logs boundary traffic.

After 90 days, the plant still has a lot of work, but the biggest risks are visible. Instead of one flat network, it has the beginning of a zones and conduits architecture, documentation, owners and a further segmentation plan.

How can ccyber.io help?

ccyber.io helps industrial companies translate IEC 62443 into a practical zones, conduits and OT segmentation project. We do not start from buying a firewall. We start from processes, assets, flows, risk and production dependencies.

We can support your organization with:

  • IEC 62443 gap analysis
  • OT risk assessment
  • OT asset inventory
  • zone and conduit mapping
  • IT/OT communication matrix
  • industrial DMZ design
  • supplier remote access review
  • OT network segmentation
  • IT/OT isolation procedure
  • monitoring at zone boundaries
  • plant ransomware tabletop
  • 30, 60, 90-day and 12-month OT security roadmap

The best first step is an IEC 62443 Zones and Conduits Workshop. In a short workshop, the company can determine which zones exist today, which conduits are critical, where the biggest risks are, which connections should be restricted and how to prepare a realistic segmentation roadmap without stopping production.

FAQ

What is a zone in IEC 62443?

A zone is a group of OT or IT/OT assets with similar function, risk and security requirements. It may include a line, SCADA system, engineering workstations, DMZ or process safety systems.

What is a conduit in IEC 62443?

A conduit is controlled communication between zones. It defines who can communicate with whom, using which protocol, in which direction, for what purpose and under which conditions.

Is a VLAN enough for OT segmentation?

No. A VLAN can be part of segmentation, but traffic rules, firewalls, owners, monitoring, documentation, testing and change process are also needed.

Where should a zones and conduits project start?

Start with OT asset inventory, process map, communication flows, supplier remote access and IT/OT connections.

Is an industrial DMZ always needed?

Not always in the same form, but in many plants it is a very good way to control data exchange between IT and OT without direct access to control systems.

Who should own a zone?

Ideally the process or system owner, such as production, maintenance, OT, quality or IT. Security supports, but the owner must understand process impact.

How often should communication conduits be reviewed?

At least annually and after every major change, modernization, new line, new supplier, incident or architecture change.

Does IEC 62443 require certification?

Not every project needs to end with certification. Many companies start with practical gap analysis, zones, conduits, risk management and roadmap, then decide whether formal assessment or certification is needed.

Summary

IEC 62443 helps organize OT security through a risk-based approach, zones and communication conduits. A zone answers which assets have similar security requirements. A conduit answers which communication between zones is needed and how it should be controlled.

In practice, OT segmentation is not only a network project. It is a joint project for production, OT, IT, security, maintenance, quality and suppliers. It must consider the physical process, availability, human safety, remote access, legacy systems, backup, monitoring and change management.

The best first step is not buying another firewall, but creating a map: assets, zones, conduits, flows, owners, risks and quick actions that reduce the biggest risk. Only then does technology support a real OT security architecture.

Sources

Ransomware in Manufacturing: How to Prepare a Plant for Downtime?

Ransomware in manufacturing is not only a problem of encrypted computers. For a plant, it means the risk of halted production lines, loss of access to MES, ERP, recipes, documentation, HMI panels, engineering workstations, quality systems, warehouse and suppliers. Plant readiness starts with defining minimum production capability, IT/OT dependencies, emergency procedures, backups, manual workarounds, communications and exercises.

Prepared by: CCyber Editorial Team

Short answer

A manufacturing plant should prepare for ransomware as a real operational downtime scenario, not only as an IT issue. The key is to determine what minimum production can safely operate without some IT and OT systems, which lines are critical, which systems are required for safe startup, shutdown, quality, logistics and shipping, and who makes crisis decisions. Backup alone is not enough. The plant needs recovery tests, manual workarounds, emergency contact lists, safe IT/OT isolation, communication plan, tabletop exercises and a clear decision process for when production can safely return.

Last updated

July 2026

Who this article is for

  • manufacturing boards
  • plant managers and operations directors
  • production, maintenance and quality managers
  • CTOs, CISOs, vCISOs, IT directors and OT security teams
  • automation engineers, OT engineers, SCADA, PLC, DCS and MES teams
  • manufacturers using ERP, MES, WMS, SCADA, HMI, PLC, historians and quality systems
  • industrial, energy, food, chemical, pharmaceutical and automotive organizations
  • companies preparing for NIS2, KSC, IEC 62443, ISO 27001, cyber insurance or customer audits
  • plants that want to prepare a downtime plan for a ransomware scenario

Key takeaways

  1. Ransomware in manufacturing does not end with computers. It may stop planning, production, quality, warehouse, shipping, maintenance, communication and supplier cooperation.
  2. The key question is: what is the plant’s minimum safe production capability when some IT or OT systems are unavailable?
  3. The plant must understand IT/OT dependencies: ERP, MES, WMS, Active Directory, engineering workstations, HMI, SCADA, PLC, recipes, production plans, quality and backup.
  4. IT data backup does not equal production recovery. PLC configurations, SCADA projects, engineering workstation images, recipes, documentation, accounts, licenses and manual procedures must also be checked.
  5. The best preparation is an exercise: who stops the line, who isolates the network, who contacts suppliers, who decides to restart production and how to prove the environment is clean.

What does ransomware mean in a manufacturing plant?

Ransomware in a manufacturing plant is an attack that may block access to systems, encrypt data, steal information, stop production planning, prevent machine support, disrupt quality, warehouse, logistics or customer and supplier communication.

In a typical office, ransomware often means no access to computers, email and files. In manufacturing, it means more: possible line downtime, delivery delay, inability to release product, no access to recipes, missing quality documentation, no warehouse visibility or need for safe process shutdown.

Ransomware in manufacturing is simultaneously a problem of:

  • IT
  • OT
  • physical safety
  • business continuity
  • quality
  • logistics
  • finance
  • customer communication
  • risk management

Why is manufacturing harder than normal IT?

In IT, the main priorities are often confidentiality, integrity and availability. In OT and manufacturing, there is also safety of people, machines, processes, quality and physical continuity.

Key differences

  • not every machine can simply be turned off
  • not every OT system can be quickly patched
  • engineering workstations may run old operating systems
  • PLC and DCS may require vendor specialists
  • downtime may destroy a batch or raw material
  • production restart requires quality and safety validation
  • server backup does not mean the whole line is ready
  • system recovery may require licenses, configurations and supplier access

That is why a manufacturing ransomware plan must be prepared jointly by IT, OT, production, maintenance, quality, safety, logistics, legal, communications and the board.

Which systems can stop production?

Ransomware does not need to encrypt PLCs to stop a plant. Sometimes it is enough to encrypt the planning system, domain, engineering workstation, license server or quality documentation.

IT systems critical for production

  • ERP
  • MES
  • WMS
  • production planning system
  • finance and accounting system
  • email and messaging
  • Active Directory or Entra ID
  • backup systems
  • document management systems
  • customer and supplier service systems

OT systems critical for production

  • PLC
  • DCS
  • SCADA
  • HMI
  • engineering workstations
  • historian servers
  • recipe servers
  • visualization systems
  • process safety systems
  • online quality control systems
  • OT vendor license systems
  • remote service access

Data critical for production recovery

  • recipes
  • PLC programs
  • HMI and SCADA projects
  • DCS configurations
  • machine parameters
  • technical documentation
  • work instructions
  • quality procedures
  • bills of materials
  • production plans
  • batch status
  • product release documents

Evidence to prepare: map of systems and data required for minimum production recovery.

The key concept: minimum production capability

In a manufacturing plant, the objective is not always immediate return to full production. Often the first realistic target is minimum safe production capability: the smallest operating scope that allows production or maintenance of the most important processes without unacceptable risk.

Minimum production capability should answer:

  • which lines must return first?
  • which products are critical for customers?
  • which processes can run manually?
  • which systems must work for production to be safe?
  • which data is required for quality and compliance?
  • how many people are needed for emergency work?
  • how long can the plant operate in limited mode?
  • who approves line restart after an incident?

Without this, the company may restore servers but still not be ready for production because planning, quality, recipes, trusted engineering workstations or OT safety confirmation are missing.

How to prepare the plant for ransomware downtime?

Step 1: map IT/OT dependencies

First, understand what production depends on. A server list is not enough. A dependency map between processes, systems, data, networks, suppliers and people is required.

The map should show:

  • production lines
  • critical processes
  • IT systems supporting production
  • OT systems controlling production
  • quality systems
  • warehouse and logistics systems
  • service suppliers
  • remote access
  • domain controllers
  • backup systems
  • manual workaround points

Evidence to prepare: IT/OT dependency map for production and minimum operating capability.

Step 2: define recovery priorities

During a crisis, not everything can be restored at once. The plant must know which systems return first and why.

Example order

  1. people and process safety
  2. crisis communication
  3. identity and accounts required for recovery
  4. emergency network and administrative access
  5. backup and recovery repositories
  6. engineering workstations and OT systems required for startup
  7. MES or minimum production planning capability
  8. quality and product release
  9. warehouse and shipping
  10. ERP and full reporting

Evidence to prepare: recovery priority list approved by production, OT, IT, quality and the board.

Step 3: prepare safe production shutdown plan

Not every downtime starts with a full stop. Sometimes only part of the systems should be stopped, and sometimes IT must be disconnected from OT. The plant must make these decisions before the incident.

The plan should define:

  • when to stop a line
  • when to continue in limited mode
  • when to disconnect IT from OT
  • who can make the shutdown decision
  • how to secure work in progress
  • how to secure equipment
  • how to prevent harm to people and environment
  • how to document line status at shutdown

Evidence to prepare: safe production shutdown procedure for cyber incident scenarios.

Step 4: prepare manual or limited operation mode

Some processes can operate manually for a short time, others cannot. The worst time to determine this is the day of the incident.

Check:

  • whether paper work instructions exist
  • whether operators know how to work without MES
  • whether production can be recorded manually
  • whether quality can be handled manually
  • whether warehouse can operate without WMS
  • whether shipping can operate without full ERP
  • whether recipes are available offline
  • whether labels and documents can be issued in emergency mode

Evidence to prepare: emergency work procedures for production, quality, warehouse and shipping.

Step 5: prepare OT backups

Manufacturing backup must include more than office files. Configuration, programs, projects, workstation images and technical documentation must be backed up.

What should be backed up?

  • PLC programs
  • HMI projects
  • SCADA projects
  • DCS configurations
  • OT network configurations
  • engineering workstation images
  • OT server images
  • recipes
  • historian databases
  • licenses and license files
  • technical documentation
  • emergency instructions
  • firmware and software version list

OT backup should be separated, tested and available even when domain, email or the main IT network is unavailable.

Evidence to prepare: OT backup register and recovery test report for a selected workstation or project.

Step 6: test recovery, not only backup existence

The key question is not “do we have backup?”. The key question is “can we safely return to production from backup?”.

The test should verify:

  • whether the copy is complete
  • whether the copy is clean
  • whether passwords and licenses are available
  • whether the restored workstation works with the right software version
  • whether the PLC or SCADA project can be opened
  • whether configuration matches the actual line state
  • whether documentation allows recovery without one specific person
  • how long recovery takes

Evidence to prepare: recovery test report with time, issues and remediation actions.

Step 7: prepare a clean recovery environment

After ransomware, backups and workstations must not be connected to an environment that may still be infected. The plant should have a clean recovery network plan.

A clean environment should include:

  • separate recovery network
  • clean system images
  • verified administrator accounts
  • scanning tools
  • access to offline copies
  • verification procedure before reconnecting to OT
  • OT owner decision to return to production

Evidence to prepare: clean room recovery procedure for IT/OT.

Step 8: define IT/OT isolation rules

In many ransomware incidents, the attack starts in IT and the risk is spread to OT. The plant must know when and how to disconnect environments.

The isolation plan should define:

  • which IT/OT connections exist
  • who can decide on isolation
  • how to technically disconnect segments
  • which systems stop working after isolation
  • how production operates after isolation
  • how to reconnect after the incident
  • how to document the decision

Evidence to prepare: IT/OT isolation procedure and connection diagram between zones.

Step 9: prepare OT suppliers

In manufacturing, the company often cannot restore everything alone. An integrator, machine vendor, SCADA vendor, DCS vendor, external automation engineer or license provider may be required.

For each supplier, check:

  • who to contact in emergency mode
  • whether an SLA exists
  • whether the supplier has remote access
  • whether remote access has MFA
  • whether access can be quickly disconnected
  • whether the supplier has a copy of the project or configuration
  • whether the supplier can work offline on site
  • whether the supplier knows cyber incident procedures

Evidence to prepare: OT supplier list, emergency contacts and service dependencies.

Step 10: prepare crisis communication

Production downtime after ransomware requires communication to employees, customers, suppliers, board, insurer, regulator and sometimes media.

Prepare message templates for:

  • production employees
  • shift managers
  • suppliers
  • customers
  • board
  • insurer
  • regulator if applicable
  • media if downtime has public impact

The key: communication must be aligned with facts. Do not promise a production restart date unless you have technical, quality and operational confirmation.

Evidence to prepare: crisis communication plan for production downtime.

What do the first 24 hours look like after ransomware in a plant?

0 to 1 hour

  • confirm whether this is ransomware or suspicion
  • activate IT/OT/production/quality/board crisis team
  • secure people and the physical process
  • stop automatic actions that may increase damage
  • do not connect backups to a suspicious network
  • start timeline and decision log

1 to 4 hours

  • identify affected systems
  • decide on IT/OT segment isolation
  • check whether lines can operate safely
  • block compromised accounts and sessions
  • preserve logs and evidence
  • contact key suppliers
  • start internal communication

4 to 12 hours

  • define minimum operating scope for the plant
  • assess backup availability
  • check which data may have been stolen
  • prepare recovery plan for priority systems
  • define manual or limited work mode
  • prepare customer communication if the impact is material

12 to 24 hours

  • start the clean recovery environment
  • test copies before restoration
  • prepare decision to return first systems
  • verify administrator account security
  • align legal and insurance requirements
  • prepare status report for the board
  • confirm priorities for the next 48 hours

How to prepare a 7-day downtime plan?

The plant should have a scenario not only for several hours, but also for several days of limited operation. Ransomware downtime may last longer if the domain, workstations, backups, OT and quality need to be rebuilt and validated.

Day 1

  • people and process safety
  • isolation and containment
  • timeline and evidence
  • internal communication
  • manual work decisions

Day 2 to 3

  • critical service recovery
  • backup verification
  • work with OT suppliers
  • quality control of data and products
  • customer communication

Day 4 to 7

  • minimum production restart
  • system validation
  • return of additional lines
  • cost and loss report
  • remediation plan
  • post-incident review

Evidence to prepare: 7-day downtime scenario and minimum production capability plan.

What documents and evidence should be prepared?

Governance documents

  • plant ransomware scenario
  • business continuity plan for production
  • IT/OT incident response plan
  • crisis decision matrix
  • minimum production capability list
  • recovery priority list
  • board report

IT/OT technical documents

  • IT/OT network map
  • critical system list
  • OT asset list
  • system and firmware version list
  • administrator account list
  • remote access list
  • IT/OT isolation procedure
  • clean room recovery procedure

Backup and recovery evidence

  • IT backup register
  • OT backup register
  • recovery test report
  • offline copy list
  • people with backup access
  • procedure to scan copies before recovery
  • confirmation of license and emergency password availability

Production documents

  • manual work procedures
  • paper operator instructions
  • emergency quality procedures
  • warehouse and shipping procedures in limited mode
  • critical product and customer list
  • production release procedure after downtime

Communication documents

  • emergency contact list
  • OT supplier contacts
  • message templates
  • communication procedure outside corporate email
  • decision maker list
  • customer and supplier communication register

Which exercises should be performed?

Exercise 1: account takeover and ransomware entry into IT

Goal: check whether the company can quickly block the account, revoke sessions, stop spread and assess OT impact.

Exercise 2: no MES for 48 hours

Goal: check whether production can run manually and how to record production, quality and materials.

Exercise 3: IT/OT isolation

Goal: check which connections must be cut, who makes the decision and how production operates after disconnection.

Exercise 4: engineering workstation recovery

Goal: check whether the company has the image, licenses, projects, passwords, documentation and specialists.

Exercise 5: line return to operation

Goal: check who approves safety, quality, parameters, data and restart decision.

Exercise 6: customer communication after downtime

Goal: check how the company communicates delays, supply risk, production status and recovery plan.

Evidence to prepare: tabletop and technical recovery exercise report.

Common manufacturing plant mistakes

Mistake 1: treating ransomware as an IT problem

Ransomware in manufacturing affects the whole plant. IT may lead system recovery, but production, OT, quality and the board must make operational decisions.

Mistake 2: backup only for IT

The company backs up files and ERP, but has no current PLC programs, SCADA projects, engineering workstation images, licenses or recipes.

Mistake 3: no OT recovery test

Having a project copy does not mean it can be restored. Real recovery of selected workstations and configurations must be tested.

Mistake 4: no manual procedures

If MES, WMS or ERP does not work, operators and shift managers must know whether production can continue and how it should be documented.

Mistake 5: uncontrolled supplier remote access

Remote service access without MFA, logs, owner and end date may be an entry path or a risk during the incident.

Mistake 6: no IT/OT isolation decision

In a crisis, nobody wants to decide to disconnect systems because they do not know the impact. Decisions must be practiced earlier.

Mistake 7: recovery into an unclean environment

Restoring copies into an environment where the attacker still has access may recreate the problem or cause re-encryption.

Mistake 8: no quality involvement

Production may technically restart, but product cannot be shipped if quality data, batch traceability, validation or documentation is missing.

Mistake 9: communication without facts

Premature customer statements can cause harm. Communicate confirmed facts, impact scope and next steps.

Mistake 10: no post-incident review

If the company does not update plans, backups, segmentation, procedures and training after an incident, recurrence risk remains high.

How to measure plant readiness?

Business metrics

  • maximum acceptable downtime for each line
  • cost of one hour of downtime
  • number of critical products with emergency work plan
  • time to restart minimum production
  • number of critical customers covered by communication plan

IT/OT metrics

  • number of OT systems with current backup
  • number of tested OT recoveries
  • number of engineering workstations with system image
  • number of active supplier remote accesses
  • number of IT/OT connections with documented isolation decision

Response metrics

  • time to activate crisis team
  • time to decide on IT/OT isolation
  • time to contact key OT supplier
  • time to prepare first board status report
  • time to recover first critical system

Exercise metrics

  • number of tabletop exercises per year
  • number of technical recovery tests
  • number of departments included in exercise
  • number of gaps found during exercise
  • number of remediation actions closed on time

30, 60 and 90-day action plan

First 30 days

  • assign the ransomware readiness owner for the plant
  • identify critical lines and processes
  • prepare IT/OT dependency map
  • check connections between IT and OT
  • review supplier remote access
  • check which OT backups exist
  • define minimum production capability
  • prepare emergency contact list
  • check whether an IT/OT isolation plan exists

Days 31 to 60

  • prepare system recovery priorities
  • update backups of PLC, SCADA, HMI projects and engineering workstations
  • test recovery of one OT system or engineering workstation
  • prepare manual procedures for production, quality and warehouse
  • update crisis communication plan
  • define line restart rules
  • prepare plant ransomware playbook
  • align the role of OT suppliers during an incident

Days 61 to 90

  • run a tabletop exercise with board, IT, OT, production, quality and logistics
  • test IT/OT isolation decision
  • test scenario of working without MES or ERP
  • prepare gaps and remediation report
  • close top gaps in backup, remote access and documentation
  • prepare ransomware readiness dashboard for the board
  • define annual exercise schedule
  • decide whether OT risk assessment or IEC 62443 gap analysis is needed

Business example

A manufacturing plant uses ERP, MES, quality system, WMS, SCADA and several engineering workstations. Ransomware starts with IT account takeover and encrypts part of the office servers and planning system. Physical lines still run, but shift managers do not have access to the current plan, warehouse cannot see material status and quality cannot release batches.

The company initially assumes that restoring ERP is enough. After several hours, it turns out the problem is broader: MES depends on the domain, engineering workstations have old accounts, recipe documentation backup is outdated, and the SCADA supplier has remote access nobody can quickly disconnect.

After the incident, the plant prepares a minimum production capability plan. It defines critical lines, which documents must be available offline, how quality works manually, how to operate without MES for 48 hours, which OT backups are required and who decides on IT/OT isolation.

After 90 days, the company has an IT/OT dependency map, PLC and SCADA project backups, an engineering workstation recovery test, manual work procedures and a tabletop exercise. The plant is not immune to every attack, but has a much better chance to avoid chaos and return safely.

How can ccyber.io help?

ccyber.io helps manufacturing plants prepare for ransomware and downtime in IT/OT environments. We combine cybersecurity, OT, business continuity, production, quality, supplier and board perspectives.

We can support your organization with:

  • OT ransomware readiness assessment
  • IT/OT dependency mapping
  • minimum production capability definition
  • backup and recovery review for OT
  • engineering workstation or OT system recovery test
  • IT/OT isolation procedure
  • supplier remote access review
  • plant ransomware tabletop exercise
  • manual and emergency work procedures
  • crisis communication plan
  • IEC 62443 gap analysis
  • 30, 60, 90-day and 12-month OT security roadmap

The best first step is an OT Ransomware Readiness Workshop. In a short workshop, the plant can define which lines are critical, which systems they depend on, which backups are needed, what minimum production capability looks like and which decisions must be practiced before an incident.

FAQ

Can ransomware stop production even if it does not encrypt PLCs?

Yes. It is enough to stop ERP, MES, WMS, documentation, quality, engineering workstations, domain accounts or supplier communication. Production depends on many IT and OT systems.

Is IT backup enough for a manufacturing plant?

No. The company also needs copies of PLC, HMI, SCADA and DCS configurations, recipes, engineering workstation images, licenses, technical documentation and emergency procedures.

What is minimum production capability?

It is the smallest safe and operationally meaningful plant operating scope after an incident. It does not mean full production, but controlled return of the most important lines or processes.

Who should decide that a line can return to operation?

The decision should be joint: production, OT, IT, quality, safety and the board. It should not be only a technical “the server works, so we restart”.

Can production continue without MES?

Sometimes yes, but only if manual procedures, quality control, production recording, access to the plan and a clear decision on acceptable duration exist.

Should OT be disconnected from IT during ransomware?

It depends on the situation, but the plant should have a prepared and exercised IT/OT isolation procedure. During crisis, the impact of the decision must be known.

How often should OT recovery be tested?

At least annually for key systems and after major changes. For the most critical lines, selected elements should be tested more often.

Where should preparation start?

Start with an IT/OT dependency map, critical line list, OT backup review, supplier remote access, isolation procedure and a ransomware tabletop exercise.

Summary

Ransomware in manufacturing is an operational problem, not only an IT problem. It can stop lines, quality, warehouse, shipping, planning, documentation and customer communication. That is why a plant must prepare for downtime as a real crisis event.

The most important elements are IT/OT dependency map, minimum production capability, recovery priorities, OT backups, recovery tests, manual procedures, IT/OT isolation, supplier remote access, crisis communication and exercises.

The best rule is: do not ask only whether you can recover data. Ask whether the plant can safely, quality-wise and operationally return to production even when some systems are unavailable for several days.

Sources

IEC 62443 vs ISO/IEC 27001: Which One Should Industrial Companies Choose?

Industrial companies usually should not choose between IEC 62443 and ISO/IEC 27001. ISO/IEC 27001 builds an information security management system for the whole organization, while IEC 62443 helps secure OT, SCADA, PLC, DCS, zones, conduits, integrators and automation suppliers. The best approach is ISO/IEC 27001 for governance and IEC 62443 for the industrial environment.

Prepared by: CCyber Editorial Team

Short answer

In industrial companies, the best answer is usually: use both standards, but for different purposes. Choose ISO/IEC 27001 as the information security management system for the whole organization: policies, risks, roles, audits, board oversight, suppliers and continual improvement. Choose IEC 62443 as the specialist standard for OT: zones, conduits, security levels, requirements for control systems, components, integrators and automation suppliers. ISO/IEC 27001 helps manage security. IEC 62443 helps secure the industrial environment.

Last updated

July 2026

Who this article is for

  • boards of manufacturing companies
  • operations and production directors
  • maintenance managers
  • automation engineers and OT engineers
  • CISOs, CTOs and IT directors
  • people responsible for ISO 27001
  • people responsible for IEC 62443
  • critical infrastructure operators
  • industrial, energy, water, transport, logistics and healthcare organizations
  • OT integrators and automation suppliers
  • companies preparing for NIS2, KSC, customer audits or supply chain requirements

Key takeaways

  1. ISO/IEC 27001 and IEC 62443 are not substitutes. ISO/IEC 27001 is an information security management system standard, while IEC 62443 is a family of standards for industrial automation and control systems security.
  2. ISO/IEC 27001 works well as a governance framework for the whole company: risks, policies, audits, suppliers, board oversight and continual improvement.
  3. IEC 62443 is the better choice for securing OT in practice: PLC, SCADA, DCS, HMI, engineering workstations, zones, conduits, integrators and automation service providers.
  4. An ISO/IEC 27001 certificate does not automatically mean that a plant has well-secured OT. The certification scope and actual industrial controls must be checked.
  5. The best model for industry is ISO/IEC 27001 as the management system and IEC 62443 as the specialist technical and organizational requirements for OT.

What is ISO/IEC 27001?

ISO/IEC 27001 is an international standard defining requirements for an information security management system, or ISMS. It helps an organization establish, implement, maintain and improve information security using a risk-based approach.

ISO/IEC 27001 covers, among other areas:

  • organizational context
  • leadership and board accountability
  • information security policies
  • risk assessment
  • risk treatment
  • security objectives
  • employee competence and awareness
  • documented information control
  • monitoring and measurement
  • internal audits
  • management reviews
  • corrective actions
  • Annex A controls

The greatest value of ISO/IEC 27001 is organizing security management across the organization. The standard helps answer: does the company have a repeatable system for managing information risk?

What is IEC 62443?

IEC 62443 is a family of cybersecurity standards for industrial automation and control systems, often referred to as IACS. It applies to OT environments where digital systems affect physical processes.

IEC 62443 is especially important for:

  • manufacturing plants
  • energy
  • water utilities
  • transport
  • logistics
  • critical infrastructure
  • building automation
  • medical and technical systems
  • industrial integrators
  • OT component suppliers
  • OT maintenance service providers

IEC 62443 helps answer: how do we secure control systems, automation and OT in a way that matches industrial risk?

The simplest comparison

ISO/IEC 27001

  • type: information security management system
  • scope: whole organization or selected ISMS scope
  • main goal: managing information security risk
  • strongest value: governance, auditability, certification, continual improvement
  • best for: board, IT, compliance, suppliers, policies, risks, processes
  • limitation: does not automatically provide detailed OT security architecture

IEC 62443

  • type: family of standards for IACS and OT security
  • scope: industrial systems, automation, control, components and suppliers
  • main goal: control system security throughout the lifecycle
  • strongest value: zones, conduits, security levels, OT technical requirements
  • best for: SCADA, PLC, DCS, HMI, OT, integrators, automation suppliers, industrial systems
  • limitation: does not replace a full organization-wide information security management system

When should ISO/IEC 27001 be chosen?

When the company needs a certificate for customers

ISO/IEC 27001 is recognized in B2B sales, tenders, customer audits and partner discussions. When customers ask for an information security certificate, they usually mean ISO/IEC 27001.

It is a strong choice when the company:

  • sells to large B2B customers
  • handles customer data
  • participates in tenders
  • must answer security questionnaires
  • wants to show security management maturity
  • needs a formal ISMS

When the company wants to organize governance

ISO/IEC 27001 is very useful for organizing information security management: roles, policies, risk assessments, documentation, corrective actions and management reviews.

In industry, ISO/IEC 27001 can help with:

  • board-level cyber risk management
  • security policies
  • supplier management
  • employee training
  • incident response
  • business continuity
  • internal audit
  • board reporting

When the company prepares for NIS2, KSC or customer requirements

ISO/IEC 27001 can be a good backbone for risk management and evidence. It helps create a risk register, risk treatment plan, policies, procedures and evidence needed in audits and regulatory requirements.

Important note: ISO/IEC 27001 helps, but does not automatically replace detailed NIS2, KSC or OT requirement analysis.

When should IEC 62443 be chosen?

When the problem concerns OT, not only IT

If the company has PLC, SCADA, DCS, HMI, engineering workstations, supplier remote access, industrial networks or production lines, IEC 62443 is the more natural technical and operational standard.

It is a strong choice when the company wants to secure:

  • PLC controllers
  • SCADA system
  • DCS
  • HMI
  • engineering workstations
  • safety systems
  • industrial networks
  • integrator remote access
  • IT-OT segmentation
  • configuration and program backups

When the company needs zones and conduits

IEC 62443 helps divide the OT environment into zones and conduits. This is very practical in OT because not every system should communicate with every other system.

Example:

  • IT zone
  • industrial DMZ zone
  • SCADA zone
  • production line zone
  • safety zone
  • supplier zone
  • conduits between zones

This approach helps determine where industrial firewalls, jump servers, monitoring, protocol restrictions, MFA and access control are needed.

When the company works with integrators and automation suppliers

IEC 62443 distinguishes roles in the industrial ecosystem: asset owners, integrators, service providers and component manufacturers. This matters because OT security depends on many parties.

The standard helps define requirements for:

  • plant owner
  • system integrator
  • maintenance service provider
  • device manufacturer
  • software and hardware component supplier
  • remote access provider

Best recommendation for industry

The best approach is not “IEC 62443 or ISO/IEC 27001”. The best approach is:

  • ISO/IEC 27001 as the organization-wide information security management system
  • IEC 62443 as the specialist standard for OT and industrial systems
  • NIST CSF as an additional framework for risk communication and roadmap where the company needs simpler board language

In practice:

  • ISO/IEC 27001 says how to manage security
  • IEC 62443 says how to secure industrial systems
  • NIST SP 800-82 helps understand OT specifics and differences from IT
  • MITRE ATT&CK for ICS helps build realistic industrial threat scenarios

Example combined model

Layer 1: governance and ISMS

Use ISO/IEC 27001 here.

  • information security policy
  • ISMS scope
  • risk register
  • risk treatment plan
  • roles and responsibilities
  • internal audits
  • management reviews
  • corrective actions

Layer 2: OT and control systems

Use IEC 62443 here.

  • zones and conduits
  • security levels
  • control system requirements
  • IT-OT segmentation
  • supplier remote access
  • patch management in OT
  • PLC, SCADA, DCS and HMI configuration backups
  • requirements for integrators and suppliers

Layer 3: plant operational resilience

Combine ISO/IEC 27001, IEC 62443, business continuity and operational practice here.

  • OT incident response plan
  • minimum production operating plan
  • configuration recovery test
  • tabletop exercises for IT, OT and production
  • crisis communication
  • board risk reporting

Key practical differences

1. Scope

ISO/IEC 27001 covers the information security management system within a defined organizational scope. It can cover OT, but only if the company deliberately includes OT in the scope, risks and controls.

IEC 62443 is designed from the start for industrial environments, automation and control systems.

2. Language

ISO/IEC 27001 uses management language: context, risk, policies, objectives, audit, management review and improvement.

IEC 62443 uses OT language: IACS, zones, conduits, security levels, control systems, components, integrators and industrial lifecycle.

3. Certification

ISO/IEC 27001 is widely used as a certifiable management system for organizations. The certificate can be important for customers, tenders and partners.

IEC 62443 can be used to assess systems, components, development processes and suppliers, but it is not the same type of organization-wide certificate as ISO/IEC 27001. In practice, it must be clear what is being assessed: a plant, system, component, integrator process or manufacturer process.

4. Risk approach

ISO/IEC 27001 requires an information security risk management process.

IEC 62443 guides risk assessment in the context of industrial systems, zones, conduits and target security levels.

5. Security priorities

ISO/IEC 27001 often works with confidentiality, integrity and availability.

In OT, priorities are often different: safety, process availability, control integrity, product quality, environmental protection and then data confidentiality.

What to choose by company type?

Manufacturing company without ISO 27001 and without an OT security programme

Best choice: start with a short IT-OT risk assessment, then build ISO/IEC 27001 basics and IEC 62443 basics in parallel.

First actions:

  • OT asset inventory
  • IT-OT connection map
  • supplier remote access review
  • MFA for remote access
  • PLC and SCADA configuration backups
  • risk register
  • board report

Manufacturing company with ISO 27001 but without detailed OT security

Best choice: extend the existing ISMS with OT risks and use IEC 62443 for detailed industrial requirements.

Check:

  • whether OT is in the ISMS scope
  • whether the risk register includes OT
  • whether internal audits include OT
  • whether OT suppliers are assessed
  • whether zones and conduits exist
  • whether the incident plan covers OT

Plant with critical production lines

Best choice: IEC 62443 as the technical priority for OT, ISO/IEC 27001 as governance and risk management.

Priorities:

  • IT-OT segmentation
  • zones and conduits
  • supplier remote access
  • OT monitoring
  • configuration backups
  • operator emergency procedures
  • recovery test

OT integrator or automation service provider

Best choice: IEC 62443 for service and integration requirements, ISO/IEC 27001 for information security management in the company.

Priorities:

  • secure design and integration process
  • customer access control
  • remote access management
  • security of service laptops
  • change and deployment procedures
  • evidence for industrial customers

OT component or industrial device manufacturer

Best choice: IEC 62443-4-1 and IEC 62443-4-2 for product security and development process, ISO/IEC 27001 for organizational ISMS.

Priorities:

  • secure development lifecycle
  • product vulnerability management
  • secure updates
  • secure default configuration
  • product security documentation
  • customer lifecycle support

How to combine ISO/IEC 27001 and IEC 62443 step by step?

Step 1: define ISMS scope and OT scope

First determine whether OT is formally included in the information security management system. Many companies have ISO/IEC 27001 only for IT, office, data center or digital services, not for the plant and production control.

Evidence to prepare: ISMS scope and decision on which OT processes are included in the management system.

Step 2: perform an OT risk assessment

The OT risk assessment should include the physical process, safety, availability, product quality, environment, remote access, suppliers and IT-OT connections.

Evidence to prepare: OT risk register and production impact scenario map.

Step 3: design zones and conduits

Use IEC 62443 to divide the OT environment into zones and conduits. This is a practical foundation for segmentation, traffic control and security requirements.

Evidence to prepare: zones and conduits model.

Step 4: map IEC 62443 requirements to ISO/IEC 27001

Do not create two separate documentation systems. Map IEC 62443 requirements to the risk register, risk treatment plan, policies, procedures and ISMS evidence.

Evidence to prepare: ISO/IEC 27001 and IEC 62443 matrix.

Step 5: set 30, 60 and 90-day priorities

Do not try to implement everything at once. Start with actions that reduce the risk of production stoppage or incident movement from IT to OT the fastest.

Evidence to prepare: OT security roadmap linked to the ISMS.

30, 60 and 90-day action plan

First 30 days

  • determine whether OT is in the ISO/IEC 27001 scope
  • assign an OT risk owner
  • identify critical production processes
  • perform initial OT asset inventory
  • review supplier remote access
  • review IT-OT connections
  • prepare the first high-level risk list
  • prepare a board report with the recommended ISO/IEC 27001 plus IEC 62443 model

Days 31 to 60

  • complete the OT asset register
  • prepare OT network and flow map
  • define zones and conduits according to IEC 62443
  • map OT risks to the ISMS risk register
  • define requirements for supplier remote access
  • check PLC, SCADA, DCS and HMI configuration backups
  • prepare OT risk treatment plan

Days 61 to 90

  • implement quick controls for high risks
  • enable MFA for OT remote access
  • restrict critical IT-OT connections
  • prepare an OT incident response procedure
  • test recovery of one critical configuration
  • update ISMS policies and procedures with OT
  • prepare a 12-month roadmap
  • agree residual risks with the board

Selection checklist: IEC 62443 or ISO/IEC 27001?

Choose ISO/IEC 27001 first if

  • you need a certificate for customers
  • you do not have a formal ISMS
  • the board does not receive regular cyber risk reporting
  • policies, risk register and management reviews are missing
  • the company receives many security questionnaires
  • you want to organize information security across the whole organization

Choose IEC 62443 first if

  • you have PLC, SCADA, DCS or HMI systems
  • the biggest risk is production downtime
  • IT-OT connections are unclear
  • suppliers have remote access to OT
  • segmentation and zone model are missing
  • requirements for integrators and automation suppliers are missing
  • you need to secure specific control systems

Use both if

  • the company has a production plant and demanding B2B customers
  • the board wants certification, but production needs real OT controls
  • the company is preparing for NIS2 or KSC
  • customer audits cover both governance and OT
  • the company has IT, OT, cloud and remote suppliers
  • cyber risk may stop production or critical services

What documents and evidence should be prepared?

ISO/IEC 27001 documents

  • ISMS scope
  • information security policy
  • risk assessment methodology
  • risk register
  • risk treatment plan
  • statement of applicability
  • internal audit programme
  • management review
  • corrective action register

IEC 62443 documents

  • OT asset register
  • zones and conduits model
  • OT risk assessment
  • target security levels
  • system security requirements
  • requirements for integrators and service providers
  • IT-OT segmentation plan
  • supplier remote access procedure
  • OT change management procedure
  • OT patch management procedure

Documents combining both approaches

  • ISO/IEC 27001 and IEC 62443 matrix
  • one risk register covering IT and OT
  • one risk treatment plan
  • board-level cyber risk report
  • OT security roadmap
  • customer audit evidence pack
  • incident response plan covering IT and OT
  • critical system recovery plan

Common mistakes

Mistake 1: believing that ISO/IEC 27001 automatically secures OT

ISO/IEC 27001 can include OT, but only when OT is actually in scope, in the risk register, in audits and in the risk treatment plan. The certificate alone does not guarantee SCADA segmentation or secure supplier remote access.

Mistake 2: implementing IEC 62443 without governance

IEC 62443 can provide strong OT requirements, but without owners, budget, board decisions, risk register and recurring oversight, actions will remain isolated.

Mistake 3: two separate documentation worlds

Separate ISO documentation and separate IEC documentation create chaos. Requirement mapping, one risk register and one roadmap are better.

Mistake 4: treating OT like a normal IT network

OT has production constraints, safety, availability, legacy systems and physical impact risk. Standard IT methods such as aggressive scanning or fast patching must not be applied without agreement with production.

Mistake 5: ignoring OT suppliers

Integrators, maintenance teams, automation suppliers and device manufacturers strongly affect OT security. IEC 62443 helps assign requirements and responsibilities.

Mistake 6: no production involvement

Without production, maintenance and automation teams, the risk assessment will be incomplete. IT and security do not always know which systems can really stop the process.

Mistake 7: no residual risk decisions

In OT, not everything can be fixed immediately. Some changes require a maintenance window, modernization or supplier approval. Residual risk must be consciously accepted by the right people.

How to measure progress?

ISO/IEC 27001 metrics

  • number of risks with assigned owner
  • percentage of risks with treatment plan
  • number of controls with evidence
  • number of audit nonconformities
  • management review timeliness
  • number of corrective actions closed on time

IEC 62443 metrics

  • percentage of inventoried OT assets
  • number of OT zones with described requirements
  • number of conduits with technical control
  • number of IT-OT connections without owner
  • number of OT suppliers with controlled access
  • percentage of critical systems with configuration backup

Shared metrics

  • number of OT risks reported to the board
  • number of roadmap actions completed on time
  • time to restore critical system configuration
  • number of IT-OT incident exercises
  • number of accepted risks with review date
  • time to close high risks

Business example

A manufacturing company has an ISO/IEC 27001 certificate for headquarters, IT and office systems. The board assumes security is organized. During a customer audit, however, the customer asks about OT: IT-OT segmentation, supplier remote access, PLC program backups, zones, industrial traffic monitoring and OT incident response procedure.

It turns out that ISO/IEC 27001 certification does not cover production lines in detail. The risk register includes general cyber risk, but not scenarios such as production downtime, engineering workstation compromise, HMI loss or PLC program change.

The company does not abandon ISO/IEC 27001. It extends the approach. The ISMS is updated with OT risks, and IEC 62443 is used to create zones, review remote access, design segmentation and define integrator requirements. A shared IT-OT risk register, roadmap and board report are created.

After 90 days, the company has better control over production risk. ISO/IEC 27001 provides governance, while IEC 62443 provides OT language and requirements. The customer receives more credible answers, and the plant has a concrete security improvement plan.

How can ccyber.io help?

ccyber.io helps industrial companies combine ISO/IEC 27001 and IEC 62443 into one practical cybersecurity programme. The goal is not to choose a standard for the standard’s sake. The goal is to reduce production downtime risk, improve governance, prepare customer evidence and build real OT resilience.

We can support your organization with:

  • IEC 62443 gap analysis
  • ISO/IEC 27001 readiness with OT coverage
  • ISO/IEC 27001 and IEC 62443 mapping
  • OT risk assessment
  • zones and conduits model
  • IT-OT segmentation review
  • OT supplier remote access review
  • IT-OT risk register
  • 30, 60, 90-day and 12-month OT security roadmap
  • workshop for board, IT, OT and production

The best first step is a short IEC 62443 vs ISO/IEC 27001 workshop for industry. It helps determine whether the company first needs an ISMS, OT risk assessment, zone model, certification readiness or a quick plan to secure the most critical IT-OT connections.

FAQ

Are IEC 62443 and ISO/IEC 27001 competing standards?

No. They serve different purposes. ISO/IEC 27001 is for information security management systems, while IEC 62443 is for industrial automation and control systems security.

Is ISO/IEC 27001 certification enough for OT?

Not always. A certificate helps demonstrate a management system, but does not automatically prove that OT has proper segmentation, secure remote access, zones or control system recovery procedures.

When is IEC 62443 the better choice?

IEC 62443 is the better choice when the project concerns PLC, SCADA, DCS, HMI, integrators, remote access, OT segmentation, zones, conduits or requirements for control systems.

When is ISO/IEC 27001 the better choice?

ISO/IEC 27001 is the better choice when the company needs a certifiable information security management system, policies, risk register, audits, management reviews and evidence for customers.

Should a manufacturing company use both standards?

In many cases, yes. ISO/IEC 27001 can manage security at organizational level, while IEC 62443 can define requirements for OT and industrial systems.

Can IEC 62443 be implemented without ISO/IEC 27001?

Yes, especially if the company wants to secure OT quickly. However, without governance, owners, budget and reporting, actions may be hard to sustain. This is why connection with an ISMS is practical.

Can ISO/IEC 27001 be extended to OT?

Yes. OT must be deliberately included in scope, risk register, audits, risk treatment plans, supplier management, incidents and business continuity.

Where should a company start?

Start with a short assessment: does the company have an ISMS, is OT in scope, which production processes are critical, what IT-OT connections exist and which risks may stop production.

Summary

In industry, the question “IEC 62443 or ISO/IEC 27001?” is often the wrong question. A better question is: which standard solves which problem?

Choose ISO/IEC 27001 for systematic information security management, risk, audits, documentation, accountability and customer evidence. Choose IEC 62443 for securing OT, control systems, segmentation, zones, conduits, integrators and automation suppliers.

The best model for an industrial company is combining both approaches. ISO/IEC 27001 provides governance, while IEC 62443 provides detailed industrial language and requirements. This means the company does not only have a certificate or documents, but materially reduces the risk of production downtime, OT incident and loss of customer trust.

Sources

We write about regulations such as NIS2, DORA, CRA and ISO 27001, cybersecurity for SMEs and critical infrastructure, as well as cyber hygiene, emerging threats and building security awareness within organisations.

Every article delivers practical knowledge - no jargon, just concrete steps you can act on to effectively protect your data, people and business continuity.