Mastering ransomware attack simulation: a guide to cyber preparedness

Ransomware is now one of the most disruptive risks facing UK organisations of every size. In the last year alone, hundreds of significant ransomware incidents have been reported in the UK, impacting retailers, councils, healthcare providers, and critical national infrastructure, leading to a sharp rise in cyber insurance claims and business disruption.

If you are dealing with an attack or suspect that something is wrong, contact Zensec now and speak with a response specialist who can help you contain the threat, assess your exposure and guide your cybersecurity team through the next steps.

Technical controls are essential, but they are not enough on their own. To be genuinely prepared, you need to rehearse what happens when those controls fail. That is where ransomware attack simulations and structured cyber exercises come in.

Understanding ransomware attacks

Ransomware attacks involve malicious code that encrypts data, often steals it before encryption, and then demands payment in return for a decryption key or a promise not to leak the data. Typical entry points include phishing attacks, compromised remote access, exposed services and exploitation of unpatched vulnerabilities.

Real ransomware attacks show how quickly this can move from an IT problem to an operational crisis. The WannaCry outbreak in 2017 affected up to 70,000 NHS devices in England and Scotland, disrupting appointments, diverting ambulances and costing an estimated £92 million in lost output and remedial IT work.

NotPetya, initially appearing as ransomware in 2017, went on to cause an estimated 10 to 11 billion US dollars in global losses and forced organisations such as shipping giant Maersk to rebuild large parts of their infrastructure from scratch.

These such incidents highlight three key realities for UK organisations. First, ransomware is a business continuity issue, not just a technical one. Second, the blast radius often extends through supply chains and service providers. Third, the decisions taken in the first hours of an incident have long-term consequences for cost, reputation, regulatory exposure and recovery time.

Simulating ransomware attacks is about practising those decisions in a safe environment before real ransomware threatens your systems.

Simulating cyber attacks

Ransomware attack simulation is a structured way to test how your organisation would respond if real ransomware threat actors gained a foothold and started moving toward critical data and systems. There are several simulation styles, each answering slightly different questions.

Tabletop exercises

Tabletop exercises are discussion-based sessions where stakeholders walk through a realistic scenario, such as a critical file server being encrypted or backups failing at the exact moment they are needed. The UK National Cyber Security Centre (NCSC) provides free ransomware scenarios in its Exercise in a Box toolkit. It promotes tabletop exercises to stress-test incident response plans and decision-making.

Technical simulations

Technical simulations are more hands-on. In these, a specialist team emulates attacker behaviour in a controlled way. This might include attempts to move laterally, escalate privileges and reach high-value targets, while carefully avoiding any real encryption or destructive action. The focus is on testing controls such as endpoint detection, monitoring, network segmentation, and backup restoration in conditions as close to a real attack as safely possible.

For many organisations, the most valuable approach blends both. Tabletop sessions bring together IT, security personnel, legal, HR, and communications to practise the wider response, while technical ransomware simulations validate whether your defences can actually stop, detect, or contain realistic ransomware techniques.

Working with an experienced partner for ransomware attack simulation and penetration testing services helps ensure scenarios are grounded in current attacker behaviour, aligned with UK guidance and carried out safely without risking production systems.

Incident response planning

No simulation is complete without a clear incident response plan to test. A robust plan sets out who does what, in what order, and on what authority when a ransomware incident is suspected or confirmed.

At a minimum, your ransomware playbook should cover preparation, detection and triage, containment, eradication, recovery and post-incident review. In practice, that usually means defining how such incidents are escalated, who can disconnect systems or trigger disaster recovery, what evidence must be preserved for investigation, how legal and data protection obligations will be met, and how customers, regulators, and partners will be informed.

From a UK perspective, data protection obligations are critical. The Information Commissioner’s Office (ICO) stresses that organisations must implement appropriate technical and organisational measures to protect personal data, drawing on NCSC guidance for mitigating malware and ransomware. Where an incident compromises personal data, UK GDPR may require reporting to the ICO within 72 hours, as well as direct communication with affected individuals in some cases.

Simulations expose where a plan is vague, out of date or unworkable. Common gaps include uncertainty over who makes the final call on paying a ransom, confusion about when to engage insurers or law enforcement, and untested assumptions about how quickly systems can be rebuilt from backups. Each exercise should end with a concrete list of improvements to the plan and a timeline to implement them.

Security controls and vulnerabilities

Ransomware simulations are not only about people and process. They also provide a powerful way to validate the technical controls intended to prevent, detect, and limit an intrusion.

NCSC guidance emphasises fundamentals such as patch management, strong access controls including multi-factor authentication, and robust offline or ransomware-resistant backups. These basics remain among the most effective defences against ransomware gangs’ techniques.

Simulated attacks often reveal that networks are flatter than expected, that administrative privileges are too broad, that logging is incomplete, or that backups are either not recent enough or not easily restorable within the required time frame. They can also highlight risks in the supply chain, which is why the UK and partners such as Singapore have published specific guidance on managing ransomware risk in suppliers and service providers.

Running realistic ransomware scenarios in your environment under controlled conditions lets you see how these weaknesses play out in practice. For example, a ransomware simulation might explore what happens if an attacker compromises a managed service provider account, or if a single misconfigured endpoint provides a path into cloud workloads.

The aim is not to achieve perfect security, which is not realistic, but to make it significantly harder for attackers to succeed and to ensure that, if they do, you can detect and contain them quickly.

The role of security leaders

Security leaders have a central role in turning ransomware simulation from a one-off exercise into an ongoing practice.

They need to set expectations with the board that ransomware preparedness is not just about having tools and policies written down; it is about regularly testing those tools and policies against realistic scenarios. That includes ensuring senior executives participate in simulations so they understand what a real incident will feel like and what decisions they may be asked to make under pressure.

Leaders must also translate lessons from simulations into tangible improvements. That might mean prioritising network segmentation projects, improving identity and access management, funding better backup solutions or investing in user awareness and phishing resilience. It also means staying current on the latest ransomware trends, tools and initial access methods used by criminal groups targeting UK organisations.

Finally, security leaders should ensure that simulations are inclusive. Ransomware events rarely sit neatly within the security team. Legal, compliance, HR, operations, customer support, PR and executive leadership all have a role. Simulations are a chance to build relationships and rehearse cross-functional coordination before an actual crisis.

Getting started with ransomware attack simulation

If your organisation has never run a ransomware simulation, the first step is simply to start small and keep it focused.

Choose a realistic scenario based on your environment. For example, encrypted files used across the organisation, compromise of a line-of-business SaaS platform, or simultaneous impact on both production systems and backups. Decide whether your first exercise should be a tabletop discussion or a more technical engagement, and be clear about the objectives.

Are you testing decision-making, communication, detection capabilities, recovery times, or all of these? Testing your response capabilities is essential.

Use established guidance, such as NCSC’s Exercise in a Box scenarios as a foundation, then adapt them to your specific context, sector and regulatory obligations. Capture everything that worked, as well as everything that failed or took too long, and turn those findings into an action plan that is tracked to completion.

And if you are already dealing with an attack or suspect that something is wrong, you should not treat it as a drill. Contact Zensec now to speak with a response specialist who can help you contain the threat, assess your exposure and guide your cybersecurity team through the next steps.