Penetration Testing for UK Accountancy and Professional Services Firms
CREST-accredited penetration testing for UK accountancy practices, auditors, tax advisers and consulting firms. Evidence for UK GDPR Article 32, Cyber Essentials buyer requirements and cyber insurance proposal forms, across client portals, tax upload, audit data rooms and practice management platforms. Client-confidentiality-strict.
- Unlimited retesting
- Unlimited pre-retesting
- No hidden fees
“I would highly recommend EJN Labs to any organisation seeking reliable, detailed, and well-managed penetration testing services, particularly for government or enterprise-level projects.”
“There wasn’t another company we could find that could deliver what we needed in the timeframe we needed. The client loved it, and we got instant ROI from the engagement.”
penetration test, scoped to your client portal, tax upload and practice management systems, gives you evidence for UK GDPR Article 32, Cyber Essentials buyer checks and the questions on your cyber insurance proposal form.
What UK GDPR, Cyber Essentials Buyers & ICAEW Guidance Expect
UK GDPR Article 32. Client tax records, identity documents and audit working papers are personal data, much of it financially sensitive. Article 32(1)(d) requires a process for regularly testing, assessing and evaluating the effectiveness of your security measures. It does not name penetration testing as the method, but a test is the most direct evidence that your controls work. See our GDPR penetration testing page, and UK GDPR Article 32.
Cyber Essentials & cyber insurance. In our experience, some audit clients, corporate customers and referral networks ask an accountancy or professional-services firm to hold Cyber Essentials Plus before they engage. Cyber Essentials Plus is an assessor-led technical audit, not a penetration test. We certify firms directly as an IASME Cyber Essentials certification body. Separately, some UK cyber insurance applications ask whether you conduct vulnerability assessments or penetration tests and remediate critical findings. Requirements vary by insurer and policy, and we document findings and remediation against the specific questions your broker or insurer asks. DUAL cyber proposal form.
ICAEW & ACCA guidance. Professional bodies including ICAEW and ACCA publish cyber security guidance for member firms, but in our experience neither mandates a specific technical control framework or a penetration test. Our guide looks at where a penetration test fits that guidance in practice. ICAEW cyber guidance and penetration testing.
Who we test for. Accountancy practices, auditors, tax advisers, bookkeeping firms and management consultancies running client portals, tax upload systems, audit data rooms or practice management platforms. For adjacent professional-services confidentiality work see our law firm page. Our Congruent case study covers a web application and API test finished to a fixed deadline before the client’s first customer engagement.
SCOPE
What We Test for UK Accountancy & Professional Services Firms
Client Portals & Tax Upload
Client-facing portals, tax document upload and identity-document verification. Client-to-client isolation (IDOR), upload validation, and confidential report sharing between practice and client.
Audit Data Rooms & Document Sharing
Virtual data rooms, audit data rooms and file-sharing platforms. Folder and matter access boundaries, share-link leakage, document-preview API authorisation, and expired invitations that still grant access.
Practice Management Platforms
Practice management and workflow software used across a firm. Partner review and sign-off stages, staff-to-partner permission boundaries, and cross-client visibility inside a single practice platform.
Payment-Instruction & Invoice Fraud
Targeted phishing simulation against finance and practice staff. Business email compromise, invoice-fraud lures, lookalike domains and payment-instruction interception aimed at client money and firm payroll.
Accounting Software & HMRC Integrations
APIs connecting practice systems to cloud accounting software, bank-feed providers and HMRC Making Tax Digital submissions. Token scope, client-account separation, and data exposed across the integration boundary.
Microsoft 365 & Email Security
Common accountancy-firm cloud setups. Conditional access, MFA bypass, OAuth app abuse, mailbox auto-forward rules used in invoice fraud, and shared-mailbox privilege boundaries.
Internal Network & Active Directory
Internal Active Directory attacks and segregation between partner, audit, tax and admin teams. Privileged access, file-share scoping and remote-access pathway testing.
OUR PROCESS
From Scope to Attestation in 4-6 Weeks
Scoping Call
30-minute technical scoping call. Define attack surface, methodology, rules of engagement, and timeline. Fixed-price quote within 24 hours.
Active Testing
3-15 days of hands-on testing by CREST-certified pen testers, against non-production environments with synthetic client data wherever possible. Daily status updates.
Reporting
Executive summary plus full technical report with CVSS scores, reproduction steps, screenshots, and specific remediation. 60-minute walkthrough call.
Free Retest
After remediation, we retest at no extra charge. Letter of attestation provided for buyer due diligence, Cyber Essentials evidence packs, or cyber insurance underwriting.
CREDENTIALS
Verified Accreditations Auditors Accept
Every credential below is independently verifiable. UK procurement teams, FCA supervisors, ISO 27001 / SOC 2 auditors, and cyber insurance underwriters all recognise these standards.
GET YOUR QUOTE
Get a CREST Accountancy pen test quote in 24 hours
A fixed-price quote back in one business day, from a named CREST assessor. No sales pipeline, no chasing.
- CREST and IASME accredited. Testing your auditors and clients already recognise.
- Fast-track testing within 24 hours where required. Free retest of every fix included.
- Live findings via your client portal, not a four-week PDF.
- Fixed price from £3,500 for a single-role, single-app scope, agreed up front. Most engagements run £5,000 and up. No day-rate surprises.
Dan WilcocksonFounder, CelloriUnder NDA Further named references available on a scoping call.
- We reply within one business day with a fixed-price quote from a named CREST assessor.
- You approve the scope and we book a start date, usually within 24 hours.
- Live findings land in your client portal as we test, with a free retest of every fix.
Get your fixed pen test quote in 24 hours
Quote request received
We will reply within one business day with your fixed-price quote from a named CREST assessor.
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or book a 20-min scoping call first
We reply within one business day. Your data stays with us. No newsletter signup.
COMPLIANCE READY
Reports Aligned to Every Framework
Findings map to specific control references in each framework, so your audit team submits the report directly without translation work.
UK GDPR
Article 32(1)(d) evidence that you regularly test the effectiveness of your security measures.
Cyber Essentials Plus
An assessor-led technical audit, not a penetration test. IASME-direct certification through our certification body status.
ISO 27001
Annex A 8.8 technical vulnerability management, once you declare that control applicable.
Cyber Insurance
Findings and remediation documented against the questions on your proposal form. Requirements vary by insurer and policy.
ICAEW / ACCA Guidance
Neither mandates a specific technical framework or a penetration test; our report supports the due-diligence evidence a member firm chooses to keep.
SOC 2 Vendor Assurance
CC4.1 names penetration testing as an example evaluation method corporate clients use to assess supplier risk. Not a mandate.
PRICING
Indicative Engagement Pricing
Fixed-price quotes confirmed during scoping. Free retest, executive summary, walkthrough call, and letter of attestation included.
Depends on service + scope
External / web / API / mobile single-target engagement. CREST-certified delivery. Around 3 to 5 working days from kickoff to report.
Get a fixed quoteDepends on service + scope
Multi-target combined engagement (web + API + external + AD), or single complex target. Typically 7-10 days.
Get a fixed quoteDepends on service + scope
Full-stack engagement (multiple cloud accounts, hybrid AD, complex web + API + mobile). Typically 12-15+ days.
Get a fixed quoteWHY EJN LABS
What You Get From Accountancy & Professional Services Penetration Testing
Six concrete differentiators competitors don’t all match.
CREST-Certified Testers, Verifiable
Every test by a CREST-certified pen tester (CRT, CCT APP, CCT INF where applicable). Verify our company status at crest-approved.org.
24-Hour Startup, Where Required
From signed scope to active testing in a single business day for incident response, audit deadlines, or regulator-driven timelines.
Live Findings, Not 4-Week PDFs
Critical issues reported during testing through your client portal. Your team remediates while testing continues.
Audit-Ready Reports
Executive summary plus full technical report with CVSS scores and explicit framework mappings (ISO 27001, SOC 2, PCI DSS, FCA SYSC).
Free Retests, Standard
Verify remediation of every finding before close-out. Letter of attestation for audit submission included. Most competitors charge £1,500-£3,000 per retest.
UK-Based CREST Testers
Every engagement performed by vetted, UK-based CREST-certified testers, matched to your needs, security clearance, and compliance scope.
FAQ
Frequently Asked
Which accountancy and professional-services organisations do you test for?
Accountancy practices, auditors, tax advisers, bookkeeping firms and management consultancies using client portals, tax upload systems, audit data rooms or practice management platforms.
What does an accountancy test check that a standard web app test does not?
Client-to-client isolation across the portal, partner review and sign-off boundaries in practice management workflows, how identity documents and tax records are stored, and whether a client or shared link can reach another client’s confidential report.
We only have a client portal, not a full internal IT estate. Is a web application test enough?
In our experience a web application and API test covers most of the risk for a practice built around a client portal, tax upload and practice management platform. We scope internal network and Microsoft 365 testing alongside it where the practice also manages its own domain and email.
Can you test our tax-upload portal built on Xero or QuickBooks before we launch it to clients, with evidence for UK GDPR?
Yes. We test the portal and its integration with your accounting software, covering client-to-client isolation, upload validation and API token scope, and the report maps to UK GDPR Article 32(1)(d) evidence of regular security testing.
Can you test our practice management software, or is that the vendor’s responsibility?
We test how your firm has configured and connects to practice management software: partner review and staff permission boundaries, exports, and integrations. Vulnerabilities in the vendor’s own codebase are reported to you for escalation to the vendor.
Can you help with payment-instruction and invoice fraud specifically?
Yes. Our phishing assessments include invoice-fraud and business email compromise scenarios aimed at finance and practice staff: lookalike domains, payment-instruction interception, and partner-impersonation lures.
Does your report help with Cyber Essentials or a corporate client’s supplier due diligence?
Yes. Cyber Essentials Plus is a separate assessor-led audit, and we certify firms directly as an IASME Cyber Essentials certification body. Our penetration test report and letter of attestation give you additional technical evidence for corporate clients and audit networks that ask about supplier security as part of their due diligence.
What’s in the report?
Executive summary (board-ready), technical report with CVSS 3.1 scores, reproduction steps, screenshots, specific remediation guidance, and a 60-minute walkthrough call. Letter of attestation issued after free retest.
Do you sign NDAs?
Yes. We sign client-supplied NDAs as standard. Engagement data is protected under our ISO 27001 (BSI-audited) information security management system.
How quickly can you start?
From signed scope to active testing in 24 hours where required. Standard pipeline is 3-5 business days from initial scoping call to test start.
Are your testers UK-based and what certifications do they hold?
Every engagement is performed by vetted UK-based CREST-certified testers matched to your engagement based on security clearance, compliance scope, and sector specialism. Testers hold CREST certifications relevant to their discipline (CRT, CCT APP, CCT INF, CCSAM).
20+ CREST-accredited testing services in one place
Web, mobile, API, cloud, AI, infrastructure, red team. Pick the test that fits your environment.
Get my Accountancy pen test scope
A CREST-certified pen tester will contact you within one business day with a fixed price aligned to your client-confidentiality and UK GDPR needs.
