# Web App Logic

> Web application logic testing - business logic flaws, race conditions, access control, cache poisoning/deception, and information disclosure.

- Skill: `transilienceai/web-app-logic` (Agent Skill, multi-file: 56 files)
- Install (CLI): `npx skillmds@latest add transilienceai/web-app-logic`
- Raw SKILL.md: https://api.skillmd.com/api/skills/transilienceai/web-app-logic/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: transilienceai (https://skillmd.com/u/transilienceai)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/transilienceai/web-app-logic

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# Web Application Logic

Test for logic flaws and application-specific vulnerabilities that automated scanners miss.

## Techniques

| Type | Key Vectors |
|------|-------------|
| **Business Logic** | Workflow bypass, price manipulation, feature abuse |
| **Race Conditions** | TOCTOU, limit bypass, double-spend, parallel requests |
| **Access Control** | IDOR, horizontal/vertical privilege escalation, forced browsing |
| **Cache Poisoning** | Unkeyed headers/parameters, fat GET, response splitting |
| **Cache Deception** | Path confusion, static extension tricks, normalization |
| **Info Disclosure** | Error messages, debug endpoints, source code, metadata |

## Workflow

1. Map application workflows and business rules
2. Identify state-dependent operations and trust boundaries
3. Test logic assumptions with edge cases and race conditions
4. Verify access control across user roles
5. Document impact with PoC demonstrations

## Reference

- `reference/business-logic*.md` - Business logic testing techniques
- `reference/race-conditions*.md` - Race condition exploitation
- `reference/access-control*.md` - Access control bypass methods
- `reference/web-cache-poisoning*.md` - Cache poisoning techniques
- `reference/web-cache-deception*.md` - Cache deception attacks
- `reference/information-disclosure*.md` - Information disclosure testing