FinTech security testing: what you need beyond pen tests

Introduction

Penetration tests are important — but they’re not enough. In FinTech, where money, identities, and legal exposure are at stake, real security testing needs to go deeper.

This article explores the critical security testing activities FinTech teams should implement beyond standard pen testing — and how to bake these into your QA and SDLC process.

🔒 Why FinTech Requires Deeper Security Testing

You handle money movement, KYC data, tax records, and account access
A misconfigured API, exposed webhook, or faulty logic can cost millions
You must pass compliance audits (e.g., SOC 2, ISO 27001, PCI DSS)
Modern attacks target logic flaws, not just infrastructure

✅ What to Test (Beyond Traditional Pen Testing)

1. Authentication & Session Handling

Token expiration and refresh flows
Session hijacking and replay prevention
Multi-device session behavior
Forced logout after suspicious activity
Brute-force and credential stuffing resistance

2. Role and Permission Logic

User A cannot access User B’s account (horizontal privilege)
Finance/Admin roles behave as scoped
Approver-only actions can’t be triggered via dev tools or APIs
UI + API permissions are aligned
Role escalation attempts blocked (e.g., spoofed JWT)

3. KYC, AML, and Compliance Edge Cases

Invalid/incomplete KYC uploads handled securely
Bypassing KYC via API is impossible
AML logic can’t be skipped with crafted data
Country restrictions enforced server-side
Audit logs and versioning protected from tampering

4. Secure Data Flow Testing

Encryption of PII at rest and in transit
Internal APIs don’t expose sensitive data by default
Token/ID obfuscation in URLs and logs
Secure webhook signing and verification
Secrets never returned in API responses

5. Fraud Scenarios

Double-payment prevention under race conditions
Refund abuse (partial/full loops, duplicate requests)
Fake user/invoice/payment generation
Accessing other users’ invoices or reports via predictable URLs
Bonus/fee manipulation via crafted payloads

6. Automated Security Tests in CI/CD

Static code analysis for secrets (e.g., GitLeaks, TruffleHog)
Dependency scanning for CVEs (e.g., Snyk, Dependabot)
API security regression tests (Postman, Rest Assured)
Schema enforcement and validation (OpenAPI, ZAP rulesets)
Security smoke tests in pre-release pipelines

🔧 Tools That Complement Pen Testing

Tool	Use Case
ZAP / Burp Suite	Manual/automated HTTP testing
OWASP Amass / Nuclei	Surface asset discovery and scanning
TruffleHog / GitLeaks	Secrets detection in source code
Snyk / Dependabot	Dependency CVE tracking and fixes
OpenAPI validators	Schema-based contract validation
Postman / Newman	Automated security and permission checks

📋 Sample Security Test Matrix for QA Teams

Area	Test	Automated?	Run Frequency
Session management	Expired token + reuse attempt	✅	Per build
KYC bypass	Submit payment before doc approval	✅	Per release
Role abuse	Finance user tries admin-only export	✅	Daily
API response validation	Ensure no internal IDs or tokens leaked	✅	CI
Invoice manipulation	Modify total via API payload	❌	Manual audit
Dependency scan	Known CVEs in payment libraries	✅	Weekly
Log and trace review	Sensitive info in logs during failure	❌	Monthly

🧠 Tips for Integrating Security into FinTech QA

Add security checks into test case reviews (not just separate audits)
Include fraud edge cases in exploratory testing
Use your own sandbox/staging environments to simulate attacker scenarios
Map every key flow (login, KYC, payment) to its security controls and failure states
Train QA engineers on basic secure coding and attack vectors

Final Thoughts

Security testing in FinTech isn’t a checkbox — it’s a mindset shift. While pen tests help you uncover infrastructure flaws, real security testing starts when QA teams simulate fraud, broken business logic, and unexpected flows across real features.

Build test coverage that covers:

What users can do
What they shouldn’t be able to do
What attackers might try to do

✅ FinTech Security Test Case Checklist

🔐 Authentication & Session Management

Test Case	Automated?	Status
Test token expiration and rejection of reused JWT/refresh tokens	✅	[ ]
Attempt login with invalid credentials repeatedly (rate limiting / lockout)	✅	[ ]
Confirm session termination on logout (all devices / only one)	✅	[ ]
Check that auth tokens aren’t exposed in URLs, logs, or error messages	✅	[ ]
Simulate simultaneous logins and session hijack attempt	❌	[ ]

🔐 Role & Access Control

Test Case	Automated?	Status
Finance user tries to access admin-only routes or actions via UI/API	✅	[ ]
Validate permission boundaries between roles (read/write/delete)	✅	[ ]
Attempt to escalate role via modified JWT or API payload	✅	[ ]
Test whether unassigned users can view or edit restricted invoices/payments	✅	[ ]

🔍 KYC, AML, and Compliance Logic

Test Case	Automated?	Status
Submit payment without completing KYC (via UI or direct API call)	✅	[ ]
Upload unsupported document types (e.g., .exe, .svg)	✅	[ ]
Test rejection of oversized or corrupted KYC files	✅	[ ]
Bypass country restrictions using a modified payload or proxy	❌	[ ]

💳 Payment & Transaction Security

Test Case	Automated?	Status
Duplicate a payment request by resending the same payload (idempotency check)	✅	[ ]
Test tampering with amount or currency field via client-side override	✅	[ ]
Simulate race condition (same account, same timestamp) for double-spending	❌	[ ]
Refund abuse: multiple refund requests on same transaction	✅	[ ]
Inspect if sensitive transaction data leaks in logs or exports	❌	[ ]

🔐 API & Webhook Security

Test Case	Automated?	Status
Send unsigned webhook → validate rejection	✅	[ ]
Replay a signed webhook → ensure no duplicate action taken	✅	[ ]
Tamper with API payload schema (extra fields, incorrect types)	✅	[ ]
Confirm APIs enforce auth and role-based access	✅	[ ]
Scan for exposure of internal fields or PII in API responses	✅	[ ]

🧼 Data Privacy & Storage

Test Case	Automated?	Status
Verify that PII and sensitive data are encrypted in transit (HTTPS, TLS config)	❌	[ ]
Test secure storage of tokens, account numbers, and tax IDs (masked or encrypted)	✅	[ ]
Attempt to access cached sensitive data post logout or token expiration	✅	[ ]
Confirm that exported reports don’t include unmasked sensitive fields	✅	[ ]

🧪 CI/CD Security Scanning

Test Case	Automated?	Status
Scan codebase for hardcoded credentials or secrets	✅	[ ]
Run dependency checks for known vulnerabilities (e.g., in crypto or payment libs)	✅	[ ]
Validate test environments don’t expose real user or payment data	✅	[ ]