Reverse Engineering a Closed Mobile Platform

The web endpoints were fortified: TLS fingerprinting, JavaScript challenges, DataDome behavioral scoring. The mobile API was the only viable path. Challenge: the app used certificate pinning, obfuscated class names, and split the API key across multiple initialization paths. Dynamic analysis required bypassing certificate pinning without triggering the app's tamper detection.

Four-phase methodology: Phase 1 — Reconnaissance: HTTP archive analysis, common endpoint pattern testing, CDN behavior mapping. Establishes baseline before touching the APK. Phase 2 — Static Analysis: APK decompilation with JADX. Systematic search for API base URLs, Authorization header construction, request signing logic, and hardcoded credentials across 40k+ decompiled classes. Framework detection (Flutter vs Kotlin vs React Native) determines the correct toolchain. Phase 3 — Dynamic Instrumentation: Frida hooks on SSL_write/SSL_read at the native layer — bypasses certificate pinning at the TLS level, before the app's pinning check runs. Captures every request/response in plaintext regardless of app-level protections. Phase 4 — Validation & Specification: Replay captured requests, test parameter boundaries, document auth token lifecycle, map rate limits. Output: a complete OpenAPI-style spec with authentication flow, all endpoints, request/response schemas, and rate limit thresholds.