From e7a22d6d94a5a94f58f01a01aecb87f8943d77d5 Mon Sep 17 00:00:00 2001 From: Santosh Tripathi Date: Thu, 26 Feb 2026 21:00:44 -0800 Subject: [PATCH] [SAFE-UC-0034] Added Saved Credit Card Payment Flow usecase Signed-off-by: Santosh Tripathi --- use-cases/SAFE-UC-0034/README.md | 208 +++++++++++++++++++++++++++---- 1 file changed, 187 insertions(+), 21 deletions(-) diff --git a/use-cases/SAFE-UC-0034/README.md b/use-cases/SAFE-UC-0034/README.md index 6acbec4..8142cd8 100644 --- a/use-cases/SAFE-UC-0034/README.md +++ b/use-cases/SAFE-UC-0034/README.md @@ -1,32 +1,198 @@ -# Saved credit card payment flow +# SAFE-AUCA Industry Reference Guide: Saved Credit Card Payment Flow -> Seed page for **SAFE-AUCA**. Expand this into a full analysis using [`templates/use-case-template.md`](../../templates/use-case-template.md). +This use case describes a secure saved credit card payment workflow, focused on tokenized transaction processing, 3D Secure (SCA) enforcement, and protection against fraud and payment payload manipulation within an e-commerce environment. -## Metadata +## Table of Contents -| Field | Value | -|---|---| -| **SAFE Use Case ID** | `SAFE-UC-0034` | -| **Status** | `seed` | -| **NAICS 2022** | `Finance and Insurance (52)`, `Financial Transactions Processing, Reserve, and Clearinghouse Activities (522320)` | -| **Last updated** | `2026-02-24` | +1. [Use Case Metadata](#use-case-metadata) +2. [Executive Summary](#1-executive-summary-what--why) +3. [Industry Context & Constraints](#2-industry-context--constraints) +4. [Workflow Description & Scope](#3-workflow-description--scope) +5. [System Architecture](#4-system-architecture) +6. [Operating Modes & Agentic Flow Variants](#5-operating-modes--agentic-flow-variants) +7. [Threat Model Overview](#6-threat-model-overview-high-level) +8. [Kill-Chain Analysis](#7-kill-chain-analysis-stages----likely-failure-modes) +9. [Controls and Mitigations](#9-controls-and-mitigations-organized) +10. [Validation and Testing Plan](#10-validation-and-testing-plan) +11. [Contributors & Version History](#contributors--version-history) -## Workflow Description (Seed) +--- -Secure tokenized transaction processing, 3D Secure (SCA) enforcement, and protection against fraud and payment payload manipulation within e-commerce. +## Use Case Metadata -## In Scope / Out Of Scope +| Field | Value | +|---------------------------|---------------------------------------------------------------------------------------------| +| **SAFE Use Case ID** | SAFE-UC-0034 | +| **Status** | Draft | +| **NAICS 2022** | Finance and Insurance (52), Financial Transactions Processing, Reserve, and Clearinghouse Activities (522320) | +| **Workflow Family** | E-commerce & Payment Processing | +| **Last Updated** | 2026-02-19 | -- **In scope:** TBD -- **Out of scope:** TBD +--- -## SAFE-MCP Mapping (Seed Skeleton) +## 1. Executive Summary (What + Why) -| Kill-chain stage | Failure/attack pattern | SAFE-MCP technique(s) | Recommended controls | Tests | -|---|---|---|---|---| -| TBD | TBD | TBD | TBD | TBD | +### What this workflow does: +This workflow defines the operational and security boundaries for processing user transactions via a saved credit card flow. It details the retrieval of vaulted payment methods, communication with the Payment System (EPS), and the execution of 3D Secure step-up verification for transaction authorization. -## Next Steps +### Why it matters (Business Value): +A frictionless saved-card experience dramatically reduces cart abandonment and improves conversion rates for returning customers. Relying on vaulted tokens rather than raw Primary Account Numbers (PAN) minimizes the merchant's compliance footprint. -- Expand this page to `draft` using the full template in `templates/use-case-template.md`. -- Add public evidence links and concrete control/test mappings. +### Why it is risky / What can go wrong: +- **High-value target**: Financial transactions are attractive to attackers. +- **Account Takeover (ATO)**: Risk of attackers abusing saved payment methods. +- **Tampering or payload manipulation**: Potential for altering transaction amounts. +- **3D Secure bypass**: Attempts to evade verification challenge prompts. + +--- + +## 2. Industry Context & Constraints + +- **Industry-specific constraints**: Strict adherence to PCI-DSS, PSD2 SCA requirements, and localized data residency laws. +- **Typical workflows**: + - Customer Identity and Access Management (CIAM) + - E-Commerce Storefront + - Payment Platform + - Payment Gateway + - 3D Secure Access Control Server (ACS) +- **Must-not-fail outcomes**: + - No raw PAN exposure in logs. + - No bypass of 3D Secure challenges. + - No manipulation of final transaction amounts or currencies. +- **Operational constraints**: + - Millisecond-level latency for authorization loops. + - Graceful degradation during gateway timeouts. + - Strict least-privilege access for API tokens. + +--- + +## 3. Workflow Description & Scope + +### 3.1 Workflow Steps (Happy Path) +1. Authenticated user initiates checkout and selects a previously saved credit card. +2. Application securely retrieves the customer's vaulted payment token. +3. Frontend initiates the payment gateway interaction to evaluate transaction risks. +4. If required, the issuing bank triggers the user challenge via 3D Secure. +5. Upon successful 3D Secure authentication, the payment gateway issues a one-time cryptographic authorization payload (nonce). +6. Backend validates transaction details and submits the nonce for settlement. + +### 3.2 In-Scope / Out-of-Scope + +#### In-Scope: +- Token retrieval +- 3D Secure challenge execution +- Payload tampering prevention +- Gateway API communication +- Failure state handling + +#### Out-of-Scope: +- Raw card ingestion or vaulting process +- Merchant payout reconciliation +- Physical point-of-sale (POS) systems + +### 3.3 Assumptions: +- Application operates on tokenized data; no processing, storage, or transmission of PAN. +- Customer accounts utilize MFA. + +--- + +## 4. System Architecture + +### 4.1 Actors and Systems: +- **Human Roles**: Consumers, fraud analysts, payment engineers. +- **Systems**: + - Frontend app + - Backend Order Management System + - Payment Gateway + - Issuing Bank ACS + +### 4.2 Trusted vs. Untrusted Inputs: + +| Input/Source | Trusted? | Risk | Mitigation | +|----------------------------|--------------|--------------------------------------------|--------------------------------------| +| **Transaction Amount** | Untrusted | User/browser-supplied price manipulation | Server-side validation. | +| **Nonce** | Semi-trusted | Risk of reuse | Single-use validation. | +| **3D Secure JWT** | Mixed | Replay/signature stripping attacks | Strict signature checks. | +| **Gateway API Keys** | Sensitive | Risk of fraudulent transaction generation | Vault storage, IP restrictions. | + +### 4.3 Trust Boundaries: +- **Boundary 1**: Browser -> Backend (verify client inputs like cart totals, nonce match). +- **Boundary 2**: Backend -> Payment Gateway (Mutual TLS, API security). + +--- + +## 5. Operating Modes & Agentic Flow Variants + +### 5.1 Manual Baseline (No Agent) +- User selects saved card -> Vault token retrieved -> Payment processed. + +### 5.2 Human-in-the-Loop (HITL) +- Assistant Agent prepares the cart autonomously; human approves sensitive actions like price confirmations or 3D Secure prompts. + +### 5.3 Fully Autonomous +- Checkout Agent completes all steps autonomously, scoped within pre-approved safety thresholds. Hard caps ensure safety and prevent risks. + +--- + +## 6. Threat Model Overview (High-Level) + +### 6.1 Security Goals +- Prevent unauthorized saved-card transactions. +- Detect/stop payload tampering. +- Ensure full auditability. + +### 6.2 Threat Actors +- External attackers (e.g., ATO via stolen credentials). +- Malicious insiders. + +### 6.4 High-Impact Failures: +- Consumer harm: Unauthorized billing. +- Merchant reputation harm: Chargebacks, compliance penalties. +- Security compromises: API key leaks leading to fraudulent charges. + +--- + +## 7. Kill-Chain Analysis (Stages -> Likely Failure Modes) + +### Sample Failure Modes Include: +1. **Entry/Trigger**: Accounts are compromised (ATO). +2. **Execution**: Checkout payload tampered to alter price. +3. **Authorization**: Removal of 3D Secure challenge. +4. **Persistence**: Addition of "hidden" devices to whitelist. +5. **Exfiltration or Final Harm**: Fraud settlement or data leaks. + +Details on HITL and Full Agent variants provided in team review documents. + +--- + +## 9. Controls and Mitigations (Organized) + +### 9.1 Prevent: +- Recalculate cart totals server-side; enforce 3D Secure. +- Cryptographically bind agent tokens to verified device enclaves. + +### 9.2 Detect: +- Monitor abnormal transaction velocity + flag spikes. +- Enforce cryptographic tagging for auditability. + +### 9.3 Recover: +- Implement kill-switches for compromised agent tokens. +- Graceful fallback to HITL if automation exceeds safety policies. + +--- + +## 10. Validation and Testing Plan + +| Test Name | Scenario | Expected Outcome | +|----------------------------|------------------------------------------------------|--------------------------------------| +| **Baseline Price Check** | Tampered cart value | Server-side rejection. | +| **Token Binding** | Replay of Agent token | Signature rejection. | +| **Hard Caps** | Exceeded cart value; HITL fallback | Agent degrades; human prompt shown. | +| **Rapid Transactions** | Excessive velocity by an Agent | Circuit breaker triggers revocation. | + +--- + +## Contributors & Version History + +- **Contributors**: @santoshtrip (Initial draft), SAFE team. +- **Version 1.0**: Initial Draft (2026-02-28). \ No newline at end of file