GoCardless Integration Penetration Testing
Direct debit moves slower than card payments and that changes the attack. Nobody is stealing a card number. They are setting up a mandate against an account that is not theirs, or collecting against one that was cancelled. CREST-certified testers, fixed price from £2,790, scoped in 24 hours.
- Unlimited retesting
- No rescheduling or cancellation fees
- Fixed quote within 24 hours
“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.”
Imran SaghirProject Lead, SquareOne“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.”
Dan WilcocksonCo-Founder, CelloriCard integrations fail at the moment of payment. Direct debit integrations fail across time, because a mandate is a standing authority that outlives the checkout that created it and frequently outlives the customer relationship too.
Why direct debit integrations fail differently
The questions that follow are about authority. Can a customer create a mandate against a bank account they do not own. Does cancelling a subscription cancel the mandate. Can a payment be collected after a customer has left, and would anyone notice before the Direct Debit Guarantee claim arrives.
Webhook verification matters here as much as anywhere. GoCardless signs its webhooks, and a receiver that does not check the signature will accept a forged payment confirmation and grant whatever entitlement follows from it.
ISO 27001, SOC 2, PCI DSS and Cyber Essentials Plus audits accept manual penetration test evidence. Scan-only evidence is generally insufficient.
MANDATES, WEBHOOKS + COLLECTIONS
What we actually pen test on a GoCardless integration
Manual pen testing across mandate setup and authorisation, webhook verification, subscription and collection logic, customer data exposure and credential handling.
Mandate setup and authorisation
Whether a mandate can be created against an account the customer has not demonstrably authorised, the redirect flow and its completion handling, and whether mandate references can be enumerated or reused.
Webhook signature verification
Whether the webhook signature is verified on every event, replay of captured events, idempotency on duplicate delivery, and what a forged payment confirmation grants.
Subscription and collection logic
Whether cancelling a subscription actually cancels collection, retry handling on failed payments, amount changes applied without re-authorisation, and collections continuing past the end of a plan.
Customer and mandate data exposure
Whether one customer can reach another’s mandates, payments or bank details through your endpoints, and what account information your application stores and displays.
API credentials and access tokens
Access token storage, scoping and rotation, whether credentials have reached client-side code or version control, and what a compromised token could collect.
Guarantee and dispute handling
Refund and dispute flows, whether a customer can trigger operations against another’s payments, and whether your reconciliation would detect an unauthorised collection.
METHODOLOGY
GoCardless Integration Penetration Testing: From Scope to Attestation
CREST-aligned methodology built on OWASP Web Security Testing Guide, OWASP ASVS, NIST SP 800-115, and PTES. Each finding maps to all four standards plus your specific compliance regime.
Reconnaissance
Application mapping, technology fingerprinting, content discovery, parameter enumeration, authentication-flow analysis, role-matrix construction.
Vulnerability Assessment
Authenticated and unauthenticated automated scanning across every user role, plus targeted manual checks for known weakness patterns.
Manual Exploitation
Hands-on testing by a CREST-certified pentester. Business-logic exploitation, chained vulnerabilities, privilege escalation, impact validation.
Reporting + Retest
Executive summary, technical report with CVSS scores and reproduction steps, walkthrough call, free retest after remediation, attestation letter.
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 GoCardless integration 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 WilcocksonCo-Founder, 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
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COMPLIANCE READY
Reports Mapped to Every Framework
Findings are explicitly tagged to the relevant control reference. Your audit team submits the report directly without translation work.
ISO 27001:2022
Annex A.8.8 management of technical vulnerabilities plus A.5.15-5.18 and A.8.2-8.5 access control validation.
SOC 2 Type I & II
CC6 logical access, CC7 system operations, CC8 change management evidence.
PCI DSS
Requirement 11.4 application penetration testing across cardholder data environments, including ecommerce penetration testing for online retail platforms.
FCA SYSC
SYSC 4.1.1R, 6.1.1R, 13 mapped to each finding for FCA-regulated firms.
UK GDPR
Article 32 effectiveness testing, customer-data security controls, ICO-acceptable evidence.
Cyber Essentials Plus
Direct certification through our IASME body status, single-vendor delivery.
PRICING
Transparent GoCardless Integration Penetration Testing Pricing
Pricing depends on app complexity, user-role count, business-logic depth, and integration surface. The day count flexes; the included deliverables stay the same across all engagements.
2 to 3 testing days
Single user role, basic CRUD application, marketing website with auth. Around 5 working days from kickoff to report.
Get a fixed quote3 to 5 testing days
Multi-role SaaS, business application with payment integration. Around 8 to 12 working days from kickoff to report.
Get a fixed quote5 to 7 testing days
Multi-tenant platform, complex authorisation matrix, integration-heavy applications. Around 15 to 20 working days from kickoff to report.
Get a fixed quotePart of Technologies We Pen Test. These are examples of the stacks we publish pages for, not a complete list. If yours is not here we still test it. Related pages:
BY SECTOR
GoCardless Integration Penetration Testing for Your Sector
Sector-specialist scoping for UK businesses with sector-specific compliance regimes and threat models.
Fintech & FCA-Regulated
FCA SYSC, Open Banking FAPI 1.0, PSD2 SCA, payment-flow scrutiny, KYC/AML testing.
Fintech sector pageSaaS Companies
SOC 2 Type I & II evidence, multi-tenant boundaries, role escalation, customer-tenant isolation.
SaaS sector pageLaw Firms
SRA Cyber Standard, privileged data, conveyancing fraud defence, partner-tier procurement.
Law firm sector pageHealthcare
NHS DTAC, DSP Toolkit v6, UK GDPR Article 32, EHR systems, telehealth platforms.
Healthcare sector pageInsurance
FCA / PRA Operational Resilience, cyber underwriting, claims data, broker portals.
Insurance sector pagePublic Sector
CCS / G-Cloud framework, NCSC-aligned, citizen-facing services, PSN-compliance scrutiny.
Public sector pageWHY EJN LABS
What You Get From GoCardless Integration 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
Can you test without collecting real money?
Yes. GoCardless provides a sandbox that supports mandate creation, webhooks and payment simulation, which covers the great majority of what we test. Anything requiring live is agreed and kept minimal.
Do you cover the Direct Debit Guarantee?
We pen test the technical controls behind it: whether unauthorised collections are possible, whether they would be detected, and whether your refund handling works. The scheme obligations themselves are a compliance question rather than a testing one.
What if we use GoCardless alongside a card processor?
Common, and worth scoping together. Mixed payment estates tend to have inconsistent entitlement logic, where cancelling on one rail does not revoke access granted by the other.
Is Billing Requests in scope?
Yes. The newer Billing Requests flow changes how mandates and payments are created, so we pen test whichever flow you actually run rather than assuming the legacy redirect.
What do we receive?
A report mapped to ISO 27001 and Cyber Essentials, a developer write-up with reproduction steps, a walkthrough call, and unlimited free retesting until every finding closes.
20+ CREST-accredited testing services in one place
Web, mobile, API, cloud, AI, infrastructure, red team. Pick the test that fits your environment.
Get a fixed price for your GoCardless integration
Tell us which flow you use, whether subscriptions are in play and where your webhooks land. Fixed-price quote from a named CREST assessor within one business day.
