The Complete Guide to Cybersecurity Risk Assessment for IT and OT

Cyber risk does not stop at the boundary between corporate IT and operational technology.

For organisations operating connected IT and OT environments, a vulnerability in one part of the business can create consequences elsewhere. A compromised account might provide access to critical systems. An unpatched asset could become an entry point for an attacker. In operational environments, the resulting disruption can affect not only data, but also availability, production, service delivery and potentially safety.

A cybersecurity risk assessment helps organisations understand these connections. It identifies what needs protecting, where weaknesses exist, how credible threats could exploit them and what the consequences could be.

Done properly, it gives security leaders something more useful than a list of vulnerabilities. It provides a risk-based view of the environment that can guide investment, strengthen resilience and support business continuity.

What is a cybersecurity risk assessment?

A cybersecurity risk assessment is a structured process for identifying, analysing and evaluating cyber risks across an organisation.

Rather than asking only, “What vulnerabilities do we have?”, the assessment considers a broader set of questions:

• Which systems, assets and services are critical?

• What threats could affect them?

• Where are the vulnerabilities or weaknesses?

• How likely is a threat scenario to occur?

• What would the operational and business impact be?

• Which existing controls reduce that risk?

• What additional controls should be prioritised?

The result should help decision-makers understand both technical exposure and business impact.

For organisations with operational technology, this distinction becomes particularly important. The highest technical vulnerability score does not necessarily represent the organisation's highest operational risk.

Why IT and OT risk assessments need a different approach

IT and OT increasingly operate as interconnected environments, but they do not always have the same priorities.

Traditional IT security often places significant emphasis on protecting the confidentiality, integrity and availability of information. In OT, availability, integrity, operational continuity and safety can be particularly important.

An IT security team may, for example, see rapid patching as an obvious response to a vulnerability. An OT team may be responsible for equipment that cannot simply be taken offline during normal operations or where changes must first undergo extensive testing.

Legacy technology creates another challenge. Industrial environments can contain assets designed to remain operational for many years, sometimes considerably longer than typical enterprise IT equipment. Some may use older operating systems, proprietary protocols or equipment with limited native security capabilities.

Effective IT and OT security therefore requires risk assessments to account for the realities of both environments rather than applying a standard IT checklist to operational systems.

What should a cybersecurity risk assessment cover?

The scope will vary according to the organisation, environment and assessment objectives. However, a comprehensive assessment normally considers several interconnected areas.

1. Assets and critical systems

You cannot accurately assess cyber risk without understanding what you are protecting.

The first stage is therefore establishing visibility of relevant assets, systems, applications, devices, network infrastructure and dependencies.

In an OT environment, this might include:

• Industrial control systems

• SCADA systems

• HMIs and engineering workstations

• PLCs and other controllers

• Remote access infrastructure

• Safety-related systems

• Network and communications equipment

• Supporting IT services

The assessment should also consider how these assets support critical business or operational functions. This helps distinguish between an ordinary device and an asset whose loss could stop an essential service.

2. Threats and credible attack scenarios

The next question is not simply whether an asset can be attacked, but how a realistic attack could occur.

Relevant threats may include ransomware, credential theft, phishing, malicious insiders, compromised third parties, exploitation of vulnerabilities and unauthorised remote access.

For OT, threat scenarios should also consider how an attacker could move between connected IT and operational environments. This scenario-based approach gives cyber risk management greater context. Instead of treating every weakness independently, teams can understand potential attack paths and their consequences.

3. Vulnerabilities and security weaknesses

Assessments should identify technical and procedural weaknesses that could increase exposure.

These might include unsupported systems, weak authentication, excessive privileges, poor network segmentation, insecure remote access, missing patches, inadequate monitoring or weaknesses in backup and recovery processes.

Importantly, vulnerability identification is only part of the assessment. A vulnerability becomes much more meaningful when it is considered alongside the asset's importance, existing controls, realistic threat scenarios and potential impact.

4. Existing security controls

A good assessment should recognise what is already protecting the organisation.

This may include technical controls such as firewalls, network segmentation, endpoint protection, access controls and monitoring, alongside organisational measures such as policies, procedures, staff training and incident response plans.

Assessing control effectiveness helps establish the organisation's residual risk, rather than assuming every identified threat exists without mitigation.

5. Business and operational impact

This is where a cybersecurity risk assessment becomes particularly valuable to leadership. What actually happens if the risk materialises? Depending on the organisation, consequences could include:

• Operational disruption: Systems or services become unavailable.

• Financial loss: Downtime, recovery costs, contractual penalties or lost revenue.

• Safety consequences: A cyber incident affects systems supporting safe operations.

• Data exposure: Sensitive commercial, employee or customer information is compromised.

• Regulatory impact: The organisation fails to meet applicable cybersecurity or sector-specific obligations.

• Reputational damage: Customers, partners or stakeholders lose confidence.

Connecting technical findings with these outcomes makes prioritisation far more meaningful.

Cybersecurity risk assessment for operational technology security

OT deserves particular attention because the consequences of cyber risk can extend into the physical world. An assessment of operational technology security should therefore consider not only individual assets but also the architecture surrounding them.

That includes network zones and conduits, IT/OT interconnections, remote access routes, third-party connections, system dependencies and pathways through which an attacker could move.

For organisations operating critical systems, the assessment should also consider how cybersecurity controls interact with operational and safety requirements. A control that improves security but introduces unacceptable operational risk is unlikely to be an effective solution.

This is particularly relevant to critical infrastructure protection, where maintaining essential services can be as important as preventing unauthorised access.

A practical risk assessment process

While methodologies vary, a useful assessment generally follows a logical sequence.

• Define the scope. Establish which systems, locations, business processes and operational environments will be assessed.

• Identify critical assets and dependencies. Understand what supports essential operations and how different systems depend on one another.

• Identify threats and vulnerabilities. Examine credible threat scenarios and the weaknesses that could enable them.

• Review existing controls. Determine which safeguards are currently in place and whether they are effective.

• Assess likelihood and impact. Evaluate how plausible each risk scenario is and the consequences if it occurs.

• Determine and prioritise risk. Compare risks using a consistent methodology so resources can be focused appropriately.

• Develop a treatment plan. Define practical actions to reduce, transfer, avoid or accept identified risks.

• Review regularly. Risk assessments should be updated as systems, threats, business requirements and operating environments change.

From risk assessment to disruption risk reduction, How do cybersecurity risk assessments reduce IT and OT disruption likelihood?

Cybersecurity risk assessments reduce the likelihood of IT and OT disruption by identifying the systems and dependencies most critical to operations, assessing credible attack scenarios and highlighting weaknesses that could lead to downtime or service interruption.

By considering likelihood, operational impact and the effectiveness of existing controls, organisations can prioritise the risks most capable of disrupting critical services. This allows teams to focus remediation on areas such as network segmentation, access control, monitoring, patching, remote access and recovery planning before weaknesses are exploited.

For connected IT and OT environments, this is particularly important because an incident in one environment can affect the other. Understanding those dependencies helps organisations reduce potential attack paths, strengthen resilience and improve their ability to maintain operations during a cyber incident.

Finding risk is only useful if the organisation can act on it. A strong assessment should therefore produce a prioritised remediation roadmap rather than a long, undifferentiated list of findings. Some risks may require immediate technical remediation. Others might be better addressed through network segmentation, stronger monitoring, improved access control, revised procedures or compensating controls.

This approach supports disruption risk reduction because security investment is directed towards scenarios most capable of affecting critical operations. It can also help security leaders communicate priorities to senior management. Instead of saying, “We found 150 vulnerabilities,” they can explain which risks could interrupt an important service, how well those risks are currently controlled and what should be done next.

How risk assessments strengthen business continuity

Cybersecurity and business continuity are closely connected. A cyber incident does not need to involve data theft to cause serious damage. Ransomware, denial-of-service attacks, compromised operational systems and failures involving critical third parties can all interrupt normal operations.

Risk assessments help organisations identify these dependencies before an incident occurs.

They can reveal where a single system creates a critical point of failure, where recovery capabilities need improvement or where an organisation depends heavily on a supplier without sufficient contingency planning.

Those findings can then inform incident response, disaster recovery and business continuity planning.

The objective is not simply to prevent every possible attack. It is to make the organisation better prepared to prevent, withstand, respond to and recover from cyber disruption.

Common mistakes in IT and OT risk assessments

One of the biggest mistakes is treating the assessment as a compliance exercise rather than a decision-making tool. Other common problems include assessing IT and OT independently without considering their connections, relying exclusively on automated vulnerability scores, overlooking third-party access, failing to involve operational stakeholders and creating remediation plans without clear priorities or ownership.

Risk assessments can also become outdated quickly. New assets are introduced. Network architectures change. Suppliers gain access. New vulnerabilities emerge. Business priorities evolve.

For that reason, cyber risk management should be continuous, with formal assessments supplemented by ongoing monitoring and regular reviews.

What should you receive at the end of an assessment?

A useful cybersecurity risk assessment should leave the organisation with a clear understanding of:

• Its most important cyber risks

• The assets and operations exposed to those risks

• Existing security controls and identified gaps

• Potential business and operational consequences

• Risk priorities based on likelihood and impact

• Recommended remediation activities

• Residual risks that require ongoing management

For senior stakeholders, there should also be an understandable executive view of the findings.

Technical teams need enough detail to take action. Leadership needs enough context to make informed decisions about resources, priorities and acceptable risk.

Building a clearer picture of IT and OT cyber risk

Cybersecurity risk assessments are most valuable when they connect technology, operations and business consequences. For organisations with complex IT and OT environments, that means going beyond vulnerability scanning. It requires understanding how systems interact, what the organisation depends on, how credible attacks could develop and where security improvements will have the greatest impact.

That understanding supports stronger IT and OT security, better-informed investment, improved critical infrastructure protection and more resilient business operations.

At Complete Cyber, we help organisations assess cybersecurity risk across both IT and OT environments, translating technical findings into practical, prioritised actions.

Need a clearer view of your IT and OT cyber risk? Talk to Complete Cyber about a cybersecurity risk assessment built around your systems, operations and business priorities.