Adyen Integration Penetration Testing
Adyen signs its notifications with an HMAC key for a reason. The integrations we pen test do not always check it, and an unverified notification is a free order marked as paid. CREST-certified testers, fixed price from £3,040, 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, CelloriAdyen’s platform, drop-in components and libraries are well engineered, and attacking them is neither useful nor permitted. What is worth testing is the code around them, because that is where your order state, your entitlements and your money actually live.
Why the integration carries the risk
Notification handling is the recurring serious finding. Adyen sends asynchronous notifications carrying the authorisation result, signed with an HMAC key. Where the receiver does not verify that signature, or verifies it incorrectly, a forged notification can mark an order authorised without any payment having occurred.
After that it is amount integrity and recurring contracts: whether the value sent to Adyen is recomputed server-side, and whether a stored payment method can be used by anyone other than the shopper it belongs to.
ISO 27001, SOC 2, PCI DSS and Cyber Essentials Plus audits accept manual penetration test evidence. Scan-only evidence is generally insufficient.
NOTIFICATIONS, AMOUNTS + 3DS
What we actually pen test on an Adyen integration
Manual pen testing across notification verification, payment session and amount integrity, 3-D Secure handling, recurring contracts and credential exposure.
Notification verification
Whether the HMAC signature on every notification is verified, key rotation handling, replay of a captured notification, duplicate and out-of-order delivery, and what a forged authorisation notification achieves.
Amount and session integrity
Whether the payment amount and currency are recomputed server-side, session creation parameters, tampering with the payment request between browser and server, and multi-currency rounding.
3-D Secure and authentication
Whether 3-D Secure results are validated rather than assumed, whether a frictionless result can be forged, exemption handling, and whether an authentication failure can still produce a completed order.
Recurring and stored payment methods
Tokenised payment method storage, whether one shopper can use another’s stored method, recurring contract reuse, and subscription state against entitlement.
API credentials and key exposure
API key and HMAC key storage and rotation, whether credentials have reached client-side code or version control, web service user permissions, and what an exposed client key permits.
Refunds, captures and modifications
Authorisation to capture, refund and cancel, whether a shopper can trigger a modification against another order, and partial capture and refund logic.
METHODOLOGY
Adyen 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 Adyen 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 Adyen 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
Adyen 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 Adyen 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
Which Adyen integration types do you cover?
Drop-in, Components, Hosted Checkout and direct API integrations, plus Adyen for Platforms where you operate a marketplace. The integration type changes where the risk sits but not whether it is worth testing.
Can you test in the test environment?
Yes, and that is normally where we work. Adyen’s test environment supports the notification and authorisation flows we care about, including forged notification testing, without touching real money.
Do you check our PCI scope?
We flag anything that pulls cardholder data into your scope unnecessarily, which is a common and expensive mistake. Findings are mapped to PCI DSS Requirement 11.4 and written for a QSA.
What about Adyen for Platforms?
In scope if you use it. Marketplace and platform models introduce account holder separation, split payments and payout logic, all of which are worth attacking deliberately.
What do we receive?
A report mapped to PCI DSS, ISO 27001 and Cyber Essentials where relevant, a developer write-up with reproduction steps, a walkthrough call and unlimited free retesting.
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 Adyen integration
Tell us the integration type, whether recurring payments are in play and where your notifications land. Fixed-price quote from a named CREST assessor within one business day.
