Stripe Integration Penetration Testing
Stripe is not the weak point. Your integration might be. We pen test the part you wrote: the webhook that trusts an unsigned request, the amount that comes from the browser, and the subscription that keeps delivering after cancellation. CREST-certified testers, fixed price from £3,120, 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, CelloriStripe’s own platform and libraries are excellent, and we have no interest in attacking them. The question worth asking is what your application does with them, because that code carries the business logic and the business logic carries the money.
Why the integration is the attack surface
The single most common serious finding is webhook handling. A receiver that does not verify the Stripe signature will accept a forged event, and a forged payment_intent.succeeded marks an order paid that never was. We see it regularly, including in production systems that have been live for years.
Close behind it is the amount. If the price or quantity used to create a payment intent originates in the browser rather than being recomputed server-side from your own catalogue, it can be changed. Where a checkout is in scope, findings are mapped to PCI DSS.
ISO 27001, SOC 2, PCI DSS and Cyber Essentials Plus audits accept manual penetration test evidence. Scan-only evidence is generally insufficient.
WEBHOOKS, AMOUNTS + SUBSCRIPTIONS
What we actually pen test on a Stripe integration
Manual pen testing across webhook verification, payment intent and amount handling, subscription and entitlement logic, refunds and API key exposure.
Webhook signature verification
Whether the endpoint verifies the Stripe signature and rejects everything else, replay of a captured event, tolerance window handling, idempotency on repeated events, and what a forged success event achieves.
Amount and price integrity
Whether the charged amount is recomputed server-side from your own data, currency and zero-decimal handling, quantity and discount manipulation, and rounding abuse across multi-item carts.
Payment intent and session handling
Payment intent and checkout session creation, whether a session can be reused or attached to another user, confirmation flow tampering, and 3-D Secure handling where authentication is required.
Subscription and entitlement logic
Whether entitlement follows subscription state accurately, cancelled or past-due subscriptions that keep delivering, trial abuse and repeated trials, proration manipulation and plan switching.
API key and secret exposure
Whether a secret key has reached client-side code, key scoping and restricted keys, key rotation, and what an exposed publishable key can and cannot do.
Refunds, disputes and customer data
Refund authorisation logic, whether one customer can trigger operations against another’s payment methods, and what card and customer data your application stores that it need not.
METHODOLOGY
Stripe 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 Stripe 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 Stripe 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
Stripe 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 Stripe 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
Is this a PCI DSS assessment?
It is not a full PCI assessment, but findings are mapped to PCI DSS Requirement 11.4 and written so a QSA can use them. If you need the complete PCI scope we have a dedicated page for that and can run the two together.
Can you test without taking real payments?
Yes. We work in Stripe test mode wherever your environment supports it, which covers almost everything including webhook forgery and amount tampering. Anything genuinely requiring live mode is agreed with you first.
Will you touch our live customer data?
No. We use test accounts and test data that you provision. Where a check requires production, it is read-only, agreed in advance and logged.
Do you cover Stripe Connect?
Yes, and it deserves the attention. Platform and connected account separation, transfer and payout logic, and whether one connected account can reach another’s data are exactly the questions Connect raises.
What if we use Stripe Checkout rather than Elements?
Still worth testing. Hosted Checkout removes some client-side risk but leaves the session creation, the success and cancel handling and the webhook entirely with you, and that is where the findings are.
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 Stripe integration
Tell us whether you use Checkout or Elements, whether subscriptions or Connect are in play, and where your webhooks land. Fixed-price quote within one business day.
