Cyber due diligence is a focused security review carried out during mergers, acquisitions or investments to surface material cyber risk, estimate likely remediation costs and feed findings into deal terms. At CyPro, we run scoped technical testing and governance reviews so deal teams get a clear risk rating and a priced remediation plan.
In the UK and EU, buyers increasingly commission cyber due diligence because threats are rising: the European Union Agency for Cybersecurity's ENISA Threat Landscape 2025 highlights growing ransomware and supply‑chain risk, IBM's 2025 X‑Force Threat Index reports notable increases in credential theft and infostealers, and the UK Department for Science, Innovation and Technology summarises research estimating the average cost to a UK business after a cyber incident at about £195,000 (DSIT, 2025).
- What it is: Cyber due diligence reviews a target's security, incidents, third parties and identity controls so buyers can quantify cyber risk.
- Why it matters: The European Union Agency for Cybersecurity, IBM and the UK Department for Science, Innovation and Technology report rising ransomware, supply‑chain and credential‑theft activity, and DSIT notes average incident costs of about £195,000 (DSIT, 2025).
- Typical outputs: Risk rating, itemised remediation plan with estimated costs, suggested warranties and price adjustments.
- Timing: Initial findings are delivered based on scope and access; delivery can be expedited where targets provide rapid access to systems and documentation.
What is cyber due diligence?
Cyber due diligence is a focused security review carried out during mergers, acquisitions or investments to surface material cyber risk, quantify likely remediation cost and feed into deal terms. In the UK, cyber due diligence typically checks past incidents, third party exposure, patching, identity and access controls, and data flows.
Scope and typical outputs
Typical outputs are a risk rating, an itemised remediation plan, estimated costs and suggested warranties or price adjustments. Cyber due diligence often produces technical findings (vulnerabilities, misconfigurations), governance issues (missing policies, unclear roles) and commercial inputs (estimated fixing cost, residual risk rating). The review may also recommend specific contractual protections under UK GDPR and commercial warranties for cyber incidents.
Why deals need it
Deal teams use cyber due diligence because cyber incidents materially affect valuation and post‑deal liabilities. The UK Department for Science, Innovation and Technology found the average cost to an individual UK business of a cyber incident is approximately £195,000 in 2025 (DSIT, 2025). The ENISA Threat Landscape describes rising attacker sophistication, which increases the chance that target organisations hide historic compromises (ENISA, 2025).
Who commissions the work
Private equity buyers, strategic acquirers, boards and legal teams commonly request cyber due diligence. Technical teams supply the findings, while legal and finance use the remediation estimate to draft warranties, escrow arrangements and indemnities. In our experience at CyPro, the most valuable reviews combine technical testing with governance assessment so buyers get both an attack surface picture and a clear commercial remediation cost.
For UK organisations negotiating or accepting investment, strong cyber due diligence reduces surprise liabilities, informs warranty drafting under UK GDPR risk expectations, and helps buyers decide whether to proceed, adjust price or set conditions precedent.
How does cyber due diligence work in practice?
Cyber due diligence is a staged review that assesses an asset's real cyber risk, typically scoping, evidence collection, technical testing, findings review and remediation prioritisation within weeks. The process produces a risk-ranked report that buyers and lawyers use to set warranties, price adjustments and conditions precedent.
A practical cyber due diligence programme delivers fast, evidence-backed findings and a remediation plan so deal teams can quantify cyber risk and negotiate appropriately.
Typical stages
Scoping answers which systems, data and third parties are in scope and who on the deal team will provide access. A data request list follows, covering architecture diagrams, policies, incident logs and supplier contracts. Technical testing runs in parallel and is confined to agreed systems and time windows.
Technical methods and evidence
Technical work commonly includes authenticated vulnerability scanning, configuration reviews, log sampling and selected penetration testing of high‑risk assets. Reviewers check for unpatched CVEs, exposed services and weak identity controls. Findings are evidence-tagged so legal teams can trace each item to source documents or test output.
Deliverables and timing
Initial high-level findings typically arrive within a few days. A full report with risk-ranked issues, compliance notes and an estimated remediation cost is usually delivered in two to four weeks for a mid-market deal. Practical due diligence also provides a short remit for post-completion remediation and likely time-to-fix estimates.
Recent industry data shows third-party and credential theft remain top causes of breaches, which is why focused technical checks matter: Verizon, 2025 reports on third-party compromises and breach patterns, and the Information Commissioner’s Office (ICO, 2025) highlights the ongoing prevalence and cost of data incidents in the UK. Using targeted cyber due diligence gives deal teams the facts they need to price and contract risk sensibly.
Who needs cyber due diligence and when do PE and acquirers ask for it?
Private equity firms, strategic acquirers and boards running M&A typically ask for cyber due diligence when a target holds valuable IP, processes regulated data, runs cloud-native platforms or has had a recent incident; the check usually happens in the exclusive period or pre-sign stages.
Cyber due diligence focuses on three buyer questions: what can go wrong, how likely it is, and how much remediation will cost. For targets with third-party integrations or SaaS delivery, technical checks such as external penetration testing and logs review matter because threat actors increasingly exploit compromised credentials and supplier weaknesses. 2025 IBM X-Force Threat Index highlights the rise in credential theft that makes supplier and identity checks important.
Typical triggers that prompt buyers
Buyers commonly request cyber due diligence when a target has: high-value intellectual property, access to regulated financial or healthcare data, cloud-native or multi-tenant architectures, critical supplier roles, or a recent security incident. Regulatory exposure under UK GDPR, potential NIS2 applicability for digital service providers, and buyer appetite for warranty framing drive the timing and depth of checks.
What buyers expect from the findings
Buyers expect a concise risk rating, a remediation plan with costs and timelines, and evidence to support warranties, indemnities and escrows. Technical findings map to commercial outcomes: material vulnerabilities can become price adjustments, specific indemnities or completion conditions. The National Cyber Security Centre's guidance on securing supply chains explains why third-party weaknesses often transfer risk to buyers, making supply-chain checks a frequent part of diligence (NCSC supply-chain guidance).
How much does cyber due diligence cost in the UK?
Typical costs range by depth: a light review costs about £3,000, £8,000, a standard technical plus documentation package costs around £12,000, £50,000, and a deep technical engagement with penetration testing costs £40,000, £200,000, depending on host counts and cloud complexity.
Costs rise with the number of servers, cloud estates, codebases reviewed and whether encrypted backups, log retention analysis or source code review are included. A focused cyber due diligence engagement on a small SaaS target will sit at the low end, while a large enterprise with complex integrations and recent incidents will hit the high end.
What drives price differences?
Staff time, technical depth and testing breadth drive price. Labour-intensive tasks include authenticated penetration testing, source code review, privileged access mapping and forensic review of recent incidents. Tooling and lab time (for safe exploit testing) add fixed costs. The number of IP addresses, cloud accounts and distinct applications creates near-linear effort increases for the provider.
Regulatory context changes scope: work for targets in regulated sectors often needs evidence for UK GDPR (UK General Data Protection Regulation) and the Information Commissioner’s Office (ICO) audit trails, which lengthen reports and add cost. The ICO’s guidance on IT supplier relationships shows the kind of paperwork buyers expect when assessing third parties Information Commissioner’s Office (ICO).
Fixed price versus time and materials
Fixed-price bids suit narrow, well-scoped targets with known host counts. Time and materials suit acquisitions with limited discovery windows or uncertain complexity. For carve-outs, escrow and warranty structuring, buyers often budget both the diligence fee and a 20, 50% remediation holdback.
Threat trends affect your buyer budget: the National Cyber Security Centre’s annual analysis emphasises supply‑chain compromise and credential theft, which increases demand for deeper tests and third‑party checks National Cyber Security Centre (NCSC). In our experience, a clear scope, an accurate asset inventory and early agreement on what counts as a blocker keep cyber due diligence costs predictable and proportionate.
| Tier | Typical UK price (2026) | Included |
|---|---|---|
| Light review | £3,000, £8,000 | Documentation review, short interview, high‑level vuln scan |
| Standard technical | £12,000, £50,000 | Auth vuln scan, basic pen test, findings report, remediation plan |
| Deep technical | £40,000, £200,000 | Full pen test, code review, cloud config review, forensic checks |
What is the difference between cyber due diligence and related capabilities?
Cyber due diligence is a point‑in‑time assessment of a target’s security posture to support a deal decision, while vulnerability management and Managed Detection and Response (MDR) are ongoing services that reduce operational risk.
Scope and purpose
Cyber due diligence focuses on evidence for warranties, indemnities and pricing, not on delivering long‑term remediation. Vulnerability management is continuous discovery and patching, and MDR provides 24x7 detection and response capabilities. Buyers use cyber due diligence to quantify deal risk; security teams use vulnerability management and MDR to reduce day‑to‑day exposure.
Coverage differences and handoffs
Cyber due diligence typically includes architecture review, selective penetration testing, code review and policy checks, producing a remediation plan and a risk rating. Vulnerability management produces a repeated list of technical vulnerabilities with patching priorities, and MDR supplies telemetry and incident investigations. Findings from cyber due diligence feed into a remediation plan that a buyer may hand over to a remediation team, a retained MDR provider, or an integration programme.
For evidence of how threats are shifting, Gartner’s 2025 commentary on cyber trends highlights the rise of credential theft and cloud‑native risk, which often changes what diligence needs to cover Gartner, 2025.
When targets should fix immediately and when buyers accept risk
Buyers usually insist on immediate remediation for issues that affect deal valuation or regulatory compliance, such as active data breaches or absent encryption on regulated data. For lower severity findings, buyers may accept a remediation timetable backed by escrow or enhanced warranties. The choice depends on the buyer’s risk appetite, insurance cover and the sector’s regulator requirements, particularly where UK regulators like the Information Commissioner’s Office and the National Cyber Security Centre have explicit expectations around data protection and supply chain security.
Practical implication: include a clear scope and acceptance criteria in the sales and purchase agreement so cyber due diligence findings map cleanly to who will remediate, whether that is the seller, the buyer post‑close, or a retained MDR provider. Mandiant’s 2025 intelligence releases also show targeted campaigns that increase the value of having up‑to‑date telemetry when completing diligence Mandiant, 2025.
Using cyber due diligence alongside a matched remediation plan and an ongoing MDR or vulnerability management service gives a buyer both a defensible acquisition stance and a path to operational security. In our experience, cyber due diligence gives the deal team an actionable risk picture, while ongoing capabilities protect the business after integration.
⏰ When should you commission cyber due diligence during a deal? ⏰
Commission cyber due diligence at four decision points: early screening, before exclusivity, pre-signing for warranties and indemnities, and immediately after signing for remediation planning.
Early screening answers whether a target is worth pursuing, saving time and legal fees. Before exclusivity, a focused technical review limits deal-stopping surprises. Pre-signing diligence supports sellers and buyers to quantify warranty caps and compute cyber insurance pricing. Post-sign remediation work turns findings into an executable fix plan and budget for integration.
Speed versus depth
Fast, narrow assessments (7 to 14 days) suit early screening; deep technical diligence (30 to 90 days) suits pre-sign legal certainty. The trade-off is clear: short reviews reduce cost and speed the process, deep reviews reduce residual risk and improve warranty negotiation leverage. The UK National Cyber Security Centre (NCSC) materials on supplier assurance show why staged checks make sense for complex supply chains and regulated sectors, helping prioritise effort where risk concentrates (NCSC, 2025).
Regulatory and insurance timing
Under UK GDPR and in regulated sectors overseen by the Information Commissioner’s Office (ICO) or the Financial Conduct Authority (FCA), buyers should move from screening to a substantive review if the target holds regulated data or critical functions. Government analysis estimates an average cyber incident cost to a UK business around £195,000, so insurers and warranties will expect material evidence of controls before allocation of risk (ICO toolkit).
In our experience, staging cyber due diligence into a light-touch triage followed by a scoped technical phase keeps deals on schedule while giving legal teams evidence to set warranty limits. Use the 30 to 90 day window for targets with cloud complexity, recent incidents or multiple third parties.
How to choose a cyber due diligence provider?
Choose a provider that matches the deal speed, legal defensibility and technical depth your transaction needs, and whose reports your legal and IT teams will trust.
A good cyber due diligence provider combines fast triage, evidence-based technical testing and clear legal-grade reporting so buyers can price warranties and remediation correctly.
Start by asking whether the supplier has transaction experience in the target sector and whether their output stands up in warranties and indemnities negotiations. Next confirm scope options: desktop questionnaire only, light technical triage, or a deep technical assessment with forensic artefacts. A mixed approach often works: quick triage to meet deal timelines, then a focused technical phase on the riskiest assets.
Selection criteria
Prioritise providers who list past transactions, can deliver within 30 to 90 days and offer a legal‑grade chain of custody for evidence. Check whether the supplier performs cloud configuration checks, code review and live penetration testing, and whether they integrate their findings with remediation plans and estimated remediation effort.
Questions to ask suppliers
Ask for three priced scenarios, sample report pages, their approach to handling known vulnerabilities (CVE triage) and how they evidence access and findings. Confirm whether they will liaise with your legal advisers and insurers, and whether they can redact sensitive data from reports for wider distribution.
In our experience, a provider who can link technical findings to contractual remedies and to a post‑deal remediation roadmap reduces friction. For transactions touching designated suppliers or critical infrastructure, check government guidance on supplier designation and expectations in acquisitions via GOV.UK. For supply chain checks and practical controls, see the National Cyber Security Centre guidance on secure supply chains at NCSC.
Finally, choose a provider who will price remediation scenarios separately and who offers clear SLAs on delivery and evidence retention. That keeps the deal moving and gives the buyer defensible negotiating leverage.
Frequently asked questions
Do I need cyber due diligence if the target has Cyber Essentials or ISO 27001?
Certification alone does not replace cyber due diligence. Certifications are point-in-time and may not reflect production configurations or recent vulnerabilities. A proper diligence exercise verifies controls actually work, surfaces unpatched CVEs and uncovers recent incident history. Buyers in the UK commonly ask for both certification evidence and an independent diligence report to inform warranties and price adjustments.
How long does a typical cyber due diligence take?
A light cyber due diligence can run about five business days, while a standard technical plus documentation review usually takes two to four weeks. Deep technical or code reviews extend timelines. Urgent fast-tracks compress scope into 48 to 72 hours, but timing must be agreed with legal and deal teams to align with exclusivity and signing windows.
Can cyber due diligence be outsourced entirely to an external firm?
Yes, external firms commonly run end-to-end cyber due diligence, including technical testing, evidence review and remediation planning. Buyers should choose a supplier with deal experience, forensic capability and the ability to present findings in a legal-friendly format. Maintaining a vCISO or internal security lead helps validate commercial implications and prioritise remediation actions.
What does a cyber due diligence report typically include?
A typical cyber due diligence report includes an executive summary, risk ratings, technical findings with CVE references, a remediation plan and estimated fix costs. Reports should reference frameworks such as MITRE ATT&CK and flag any UK GDPR or ICO exposure. Buyers use these reports to shape warranties, escrows and holdbacks in the sale and purchase agreement.
How does cyber due diligence affect deal price or indemnities?
Findings from cyber due diligence commonly lead to price adjustments, bespoke indemnities or escrow amounts to cover remediation. Severe issues may trigger pre-sign remediation, a price reduction or conditional completion. Private equity buyers typically quantify remediation risk and present a costed remediation plan during negotiations to justify adjustments.
Can findings from cyber due diligence be used in regulatory notifications after a breach?
Yes, diligence discoveries can reveal incidents or data exposures that create UK GDPR notification duties to the Information Commissioner's Office (ICO). Buyers should consider legal privilege and confidentiality before sharing reports with regulators. If material incidents are found, coordinate a follow-up incident response plan and legal counsel to manage notification obligations and regulatory engagement.
