How to Conduct Cyber Due Diligence for UK Tech Deals in 2026

Cyber due diligence is the process of assessing an organisation’s cyber risk before a transaction, investment or major contract, focusing on technical controls, third parties and governance. In the UK, buyers use cyber due diligence to quantify likely remediation costs, warranty exposure and regulatory risk, including obligations under the Information Commissioner’s Office (ICO) guidance and the UK Network and Information Systems Regulations (National Cyber Security Centre, 2025), and, where EU operations are in scope, the EU NIS2 Directive (ENISA publications). At CyPro, we prioritise findings so boards can price risk and plan remediation quickly.

• What it is: Cyber due diligence inspects technical controls, supplier risk and governance to reveal liabilities that affect price and warranties.
• When to run it: Run cyber due diligence before deals, fundraises or major contracts where customer data, outsourced IT or cloud are material.
• Regulatory impact: UK regulators such as the Information Commissioner’s Office (ICO), the Financial Conduct Authority (FCA) and the UK Network and Information Systems Regulations increase post-deal exposure, and, where EU operations are in scope, the EU NIS2 Directive can also affect liability (National Cyber Security Centre, 2025).
• Practical output: Deliver clear, prioritised findings, multiple remediation scenarios and an estimated cost and timescale for decision makers.

🔍 What is cyber due diligence? 🔍

Cyber due diligence is the process of investigating an organisation’s cyber risk posture before a transaction, investment or contractual relationship, focusing on technical controls, third party relationships and governance. We use cyber due diligence to expose gaps that affect value, liability and remediation costs.

What cyber due diligence covers

Cyber due diligence typically covers four strands: Technical testing, documentation review, third party and supply chain checks, and governance and policies. Technical testing looks at vulnerability scanning, patching, identity controls and encryption. Documentation review examines policies, past incidents, incident response plans and certifications such as ISO 27001. Third party checks assess supplier risk, contractual SLAs and data flows, including the sorts of supplier controls described in the Information Commissioner’s Office guidance on IT supplier relationships (ICO). Governance checks validate board oversight, security roles, and evidence of security testing or audits.

Who commissions cyber due diligence

Buyers, investors, boards and legal teams commission cyber due diligence when a deal, fundraise or major contract is under consideration. Private equity and corporate acquirers pay most attention to cloud configuration, unresolved vulnerabilities and third party dependencies because those factors drive post-deal remediation costs. Regulators and insurers increasingly expect evidence of proportionate checks: ENISA’s 2025 analysis highlights the growing role of third parties in incidents, which makes supplier-focused due diligence more important (ENISA, 2025).

At CyPro, we structure cyber due diligence to give clear, prioritised findings, three realistic remediation scenarios and a practical estimate of cost and timescale. If you need a fast intake for bids or investor rounds, our Due Diligence as a Service and our Cyber Risk Assessment shorten decision cycles and focus remediation on the controls that matter most.

⚖️ Why do cyber due diligence in UK M&A, fundraising or procurement? ⚖️

Cyber due diligence is needed because cyber issues routinely change deal value, contract terms and post‑completion liability, so buyers, investors and procurement teams must quantify that risk before signing.

At CyPro, we see three commercial effects most often: Valuation reductions, bespoke warranty and indemnity wording, and conditional completion or escrow arrangements. Documentary reviews alone miss live technical gaps, and technical testing alone misses governance and supplier problems, so a blended approach gives the clearest picture of likely remediation costs and regulatory exposure.

What a focused cyber due diligence review looks like

Typical scope covers governance, incident history, asset inventories, patching, identity controls and supplier risk. Technical testing is usually targeted and timeboxed so it does not delay deals. Documentary checks map findings to warranties and insurance limits so legal and finance teams can model realistic tail risks.

Check type	Purpose	When to use
Documentary review	Assess policies, incident logs, contracts and certifications	Always, as the starting point
Targeted technical testing	Verify exploitability of key systems and estimate fix effort	When material systems or customer data are in scope
Supplier and third‑party review	Identify outsourced risks and gaps in supplier contracts	When services, cloud or managed providers underpin revenue
Insurance and liability mapping	Match findings to policy coverage and indemnity exposure	Before finalising warranties and escrow

Buyers must also factor wider industry trends into valuations. Verizon, 2025 shows a rising proportion of breaches involve third parties, which increases the value of supplier reviews. IBM’s 2025 Cost of a Data Breach Report highlights the large costs associated with ransomware and data loss, costs acquirers should model when setting indemnity caps.

At CyPro, we commonly combine a rapid documentary review with focused testing and a supplier check so the legal and finance teams receive a single report that includes estimated remediation costs and three priced remediation scenarios. If you need a bid‑ready option our Due Diligence as a Service shortens response times, and our Cyber Security Audit maps technical findings to warranties.

🧾 When should you do cyber due diligence during a deal? 🧾

Do it early and at three trigger points: At offer/heads of terms, before signing warranties, and again pre-completion if material changes occur. Early checks reduce transaction risk, while a pre-completion technical sweep catches recent incidents. Buyers must treat cyber due diligence as a deal-stage risk control, not a post-deal tick box.

Buyer-led triage versus full technical review

Buyer-led triage should happen with the initial offer. A triage is a documentary review of policies, recent incidents, insurance, and a brief external attack surface check. A full technical review follows when triage finds gaps, active incidents, or exposure to regulated obligations. A full review includes network tests, configuration checks and optionally live forensics to verify no ongoing compromise. At CyPro, we run a rapid triage then map findings to likely warranty exposure and remediation costs to inform price and indemnities. The phrase cyber due diligence applies to both the light-touch triage and the deep technical review.

Red flags that force immediate forensic checks

Immediate digital forensics are needed if you discover recent breaches, unexplained data exfiltration, missing incident response records, or insurers declining cover. Recent market data shows third-party risk and workforce pressures increase exposure, so sensible buyers prioritise an early technical sweep. Pre-completion checks should use forensics if triage reveals signs of compromise, and these are best run by a specialist to preserve evidence and legal privilege. We often link this to our Digital Forensics offering for fast response.

Timing matters: Move fast at offer, be thorough before signing warranties, and repeat checks pre-completion when circumstances change to reduce post-deal surprises.

🛠️ How do you run technical cyber due diligence? 🛠️

A technical review should deliver an asset-backed view of risk within a defined scope, completed with enough evidence to price remediation and warranties. We run focused testing, documentary checks and evidence collection so buyers can quantify supplier risk quickly.

Typical technical steps

Start with an inventory and scope, then move through vulnerability review, configuration checks, authentication and backup verification, and targeted exploitation where authorised. For inward-facing assets we check perimeter controls and web application security. For internal systems we review endpoint detection, patching state and privileged access controls. We include checks of CI/CD pipelines and IaC where relevant. Our sequence minimises disruption and maximises confidence in findings while keeping the review within a 5 to 15 day window.

Evidence sources, tools and practical deliverables

Evidence matters more than slides. We collect logs, configuration exports, vulnerability scan reports, authenticated test outputs, backup snapshots and source control evidence from CI/CD systems. Automated scanning tools and manual verification combine to reduce false positives. For regulatory context the ICO’s security guidance is a useful benchmark when supplier personal data processing is involved (ICO, guidance).

We package findings into three priced remediation scenarios: Quick fixes under 30 days, medium effort 30 to 90 days, and major work beyond 90 days. Each scenario includes estimated effort, likely costs and remaining residual risk. That lets commercial teams map warranty language to a realistic cost exposure.

Process and timing matter. For active deals run an initial 5 day rapid review at offer, then a deeper 10 to 15 day pre-completion review if the deal proceeds. External research shows third parties play an increasing role in breaches, which makes supplier checks legally and commercially important (Verizon, 2025).

At CyPro, we often deliver these outputs as part of our Cyber Security as a Service engagement so security teams can act on evidence immediately: The report, asset list, raw evidence and three remediation scenarios form the core deliverable.

📜 How do you assess legal and compliance risks in cyber due diligence? 📜

Answer: Identify the laws, licences and reporting duties that apply, then review contracts, SLAs, data flows, breach history and regulatory interactions to score risk and remediation urgency.

Checklist for contracts, warranties and licences

Begin by pulling executed contracts and supplier agreements that grant access to systems or data. For each contract, confirm the presence of security warranties, incident notification timescales and liability caps, and check whether third parties may subcontract processing. Under UK GDPR (the UK General Data Protection Regulation) and the Data Protection Act, data processing clauses must be explicit, so look for Data Processing Agreements and evidence of Data Protection Impact Assessments where high-risk processing exists. We include contract checks as a fixed task in our cyber strategy and roadmap engagements when clients require a remediation plan tied to legal obligations.

Data protection proof points and regulatory reporting

Verify ICO (Information Commissioner’s Office) registration or guidance alignment, breach reporting timelines and past regulatory history. Check whether the organisation has reported previous incidents to the ICO or other authorities and how they handled those reports. For third-party risk, note that industry studies show third parties feature heavily in breaches, which raises supply-chain reporting concerns; see Verizon’s 2025 DBIR and trend analysis from Gartner, 2025.

Practical outputs from this legal and compliance assessment include a scored register of contractual gaps, a short-list of GDPR evidence (DPIAs, retention schedules, consent records), and an escalated issues list for legal to negotiate before signing. Use the findings to drive board-level warranty negotiation and to set clear post-completion remediation budgets. Performing focused cyber due diligence on these points reduces the chance of surprise regulatory action, and the same checks help shape remediation timelines in our risk-led roadmaps.

☁️ How do you evaluate third-party and cloud supplier risk? ☁️

Start by treating supplier checks as a risk decision, not a checkbox: Confirm who has access, how identities are managed, whether backups are tested, and how incidents are reported. These core checks reveal whether a supplier’s weakness becomes your breach.

What questions to ask first

Ask for an asset map, a copy of the supplier’s identity and access policy, evidence of multi-factor authentication, recent penetration test reports, and backup recovery time objectives. Request contract language on incident notification timelines and data return or deletion. Use security questionnaires to capture this, but always validate answers with evidence: Screenshots, signed audit reports, or test results. Our approach to cyber due diligence treats questionnaire responses as the start of an investigation, not the end.

Key cloud technical checks

Verify Identity and Access Management (IAM) settings, role-based access control, logging and retention policies, network segmentation, and whether backups are encrypted and regularly restored. Check configuration drift in Infrastructure as Code and ensure secure default permissions on storage and databases. For public cloud, confirm whether the supplier uses customer-managed keys or platform-managed keys for encryption and who controls key rotation. Where services process personal data, check UK GDPR obligations and contractual data processing clauses.

When to escalate into deal terms

Escalate supplier risk into warranties, remediation schedules, or price adjustments when you find: Access rights that span multiple customers; backups without tested restores; no evidence of patching cadence; or unclear incident notification commitments. If a supplier cannot provide evidence within an agreed window, require a remediation plan and a deadline. Escalation can also include conditional go-live dates, holdbacks, or a requirement for a third-party audit.

For sector guidance and recent incident trends, consult the ENISA publications and specialist incident analyses from security vendors when prioritising checks: The ENISA publications and an independent incident feed from Mandiant provide useful context. Use those sources to focus your cyber due diligence effort where it matters most.

💷 How long does cyber due diligence take and how much does it cost in the UK? 💷

Typical cyber due diligence in the UK takes one week for a light triage, two to four weeks for a standard review, and four to eight weeks for a deep-dive, with prices from roughly £3,000 to £60,000 depending on scope, size and cloud footprint.

Typical timelines

A light triage, focused on security questionnaires, public exposure and a high-level risk register, usually completes within five working days. A standard review, which includes authenticated vulnerability scanning, review of policies and a small set of stakeholder interviews, typically runs two to four weeks. A full technical deep-dive, with architecture review, code checks, extended penetration testing windows and supplier contract review, often stretches four to eight weeks. Time is often driven by access delays, third-party co‑operation and the need for re-testing after fixes.

Price bands and what influences cost

Costs vary because teams price time, specialist skills and tooling. Smaller UK targets with simple, on-premise IT commonly fall in the £3,000 to £10,000 range for a standard review. Mid-market targets with cloud workloads, multiple SaaS integrations and wider user bases usually sit in the £10,000 to £30,000 band. Complex carve-outs, regulated sectors or engagements requiring deep forensic readiness checks tend towards £30,000 to £60,000. Key cost drivers include the number of IP ranges to scan, whether source code review is needed, the volume of third parties to assess and any required retesting. Third-party involvement also increases scope because supplier checks and contract reviews are required, which lengthens timelines and raises price.

Common deliverables and warranties

Standard deliverables include an executive summary, a scored issue register, a technical annex and a prioritised remediation plan. Buyers often ask for re-test clauses, time-limited warranties or an agreed statement of facts where legal teams need clearer liability positions. In our experience, combining a clear remediation timeline with a priced shortlist of fixes helps legal and finance teams set realistic post-completion budgets and supports warranty negotiation at handover.

❓ Frequently asked questions ❓