Pentest Business Logic

Purpose

Identify flaws in application workflow enforcement, business rule validation, and state machine integrity that cannot be found by taint analysis or pattern matching. These vulnerabilities require understanding intended behavior and finding deviations.

Prerequisites

Authorization Requirements

• Written authorization with explicit scope for business logic testing
• Test accounts at multiple privilege levels (user, admin, premium, etc.)
• Test payment methods or sandbox payment environment for financial testing
• Rollback plan for any data-mutating tests (order creation, account changes)

Environment Setup

• Burp Suite Professional with Repeater/Intruder configured
• Playwright or Selenium for multi-step browser automation
• Proxy configured to capture all application traffic
• Test data seeded for workflow testing (products, coupons, user accounts)

Core Workflow

1. Workflow Mapping: Extract multi-step flows (checkout, registration, approval chains, onboarding) from recon deliverables and source code. Document expected state transitions and business constraints.
2. Rule Extraction: Identify server-side business constraints — price validation, quantity limits, role-gated actions, time-based restrictions, coupon rules, referral limits.
3. Step Circumvention: Skip, replay, reorder steps in multi-step workflows. Access final-step endpoints directly without completing prerequisites (WSTG-BUSL-06).
4. Data Integrity Abuse: Submit negative quantities, zero-price items, boundary values, type confusion in business fields. Test forged request parameters (WSTG-BUSL-02/03).
5. Function Limit Bypass: Test coupon reuse, referral loops, vote stuffing, resource exhaustion through legitimate endpoints (WSTG-BUSL-05).
6. File Upload Logic: Upload unexpected file types, oversized files, polyglot files, content-type mismatch, path traversal in filenames (WSTG-BUSL-08/09).
7. Payment Testing: Price manipulation at each checkout stage, currency confusion, discount stacking, partial payment abuse (WSTG-BUSL-10).

WSTG Coverage

WSTG ID	Test Name	Status
WSTG-BUSL-01	Test Business Logic Data Validation	✅
WSTG-BUSL-02	Test Ability to Forge Requests	✅
WSTG-BUSL-03	Test Integrity Checks	✅
WSTG-BUSL-04	Test for Process Timing	✅
WSTG-BUSL-05	Test Number of Times a Function Can Be Used Limits	✅
WSTG-BUSL-06	Testing for the Circumvention of Work Flows	✅
WSTG-BUSL-07	Test Defenses Against Application Misuse	✅
WSTG-BUSL-08	Test Upload of Unexpected File Types	✅
WSTG-BUSL-09	Test Upload of Malicious Files	✅
WSTG-BUSL-10	Test Payment Functionality	✅

Tool Categories

Category	Tools	Purpose
Request Manipulation	Burp Repeater, Burp Intruder, mitmproxy	Modify request parameters, replay/reorder steps
Browser Automation	Playwright, Selenium	Multi-step workflow testing, UI interaction
Scripting	Python requests, aiohttp	Custom workflow abuse scripts, parallel requests
File Upload	custom polyglot generators, ExifTool	File type confusion, metadata injection
Payment Testing	Stripe test mode, PayPal sandbox	Safe payment manipulation testing

References

• references/tools.md - Tool function signatures and parameters
• references/workflows.md - Attack pattern definitions and test vectors