How Attackers Can Hack Your In-App Purchases (+ How You Protect Them)

Android in-app purchases can be bypassed through two main attack vectors: static analysis via reverse engineering (using Jadx to read decompiled code and APKTool to modify and repackage the APK with smali edits) and dynamic instrumentation using Frida to hook and replace runtime function calls without modifying the APK. Both attacks work even against apps using the official Google Play Billing Library. Defenses include server-side purchase token validation (so premium state is never stored client-side) and advanced obfuscation tools like DexGuard, which applies control flow obfuscation, string encryption, and code virtualization — making decompilation ineffective and detecting Frida hooks or APK repackaging at runtime.