Where payment gateways break
The complex relationships between processors, issuers, acquirers, and merchants create countless edge cases. We focus on the logical flaws that automated scanners miss entirely.
Webhook spoofing & bypass
If an attacker can forge a "payment successful" webhook to a merchant, they get goods for free. We test signature validation, replay protections, and payload tampering.
Merchant account isolation
Testing for BOLA/IDOR vulnerabilities that would allow a malicious merchant to view another merchant's transactions, modify webhooks, or alter payout accounts.
Settlement manipulation
Attacking the logic controlling how and when funds are settled. We test for negative amount injection, currency conversion rounding exploits, and delayed-capture bypasses.
Checkout manipulation
Testing the customer-facing payment pages for parameter tampering, price modification, and bypasses of 3D-Secure or OTP verification paths.
Webhook signature replay attack
The gateway correctly signed webhooks to merchants, but lacked replay protection. An attacker could capture a single $1 successful webhook payload and replay it 100 times to the merchant's endpoint, resulting in $100 of credited value. Fix priority: immediate.
PCI DSS & Security Assurance
While compliance checks are necessary, they don't catch business logic flaws. Our reviews dig into how a determined attacker would exploit the bespoke features of your transaction engine, providing real security beyond the baseline PCI requirements.
Ensure your gateway APIs are bulletproof.
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