A mobile app is not a sealed box. Once it is on someone's phone, they can decompile it, inspect its files, watch its network traffic and change how it behaves while it runs. Security that relies on "nobody will look" fails the moment somebody does.
1. Secrets hidden in the app
API keys, cloud storage credentials, encryption keys and internal URLs are regularly found inside app packages. Obfuscation slows attackers down, but it does not hide secrets. Fix: keep real secrets on the server; anything shipped in the app should be considered public.
2. Sensitive data stored on the device
Tokens, personal data and even passwords stored in plain files, databases, logs or caches can be read on a lost, rooted or compromised phone. Fix: store as little as possible, use the iOS Keychain and Android Keystore for secrets, and clear data on logout.
3. Weak protection of network traffic
Apps that accept any certificate, allow plain HTTP, or don't verify that they are talking to your real server let attackers on the same network read or alter traffic. Fix: enforce TLS everywhere, validate certificates properly, and consider certificate pinning for high-risk apps.
4. Security checks that only happen in the app
If the app decides whether a user is premium, whether a price is correct or whether a feature is allowed, an attacker can change that decision. Fix: the server must enforce every rule that matters. The app is just the display.
5. An API that trusts the app too much
Most serious mobile breaches actually happen on the backend: endpoints that return other users' data, accept changes to fields they shouldn't, or have no rate limits. See our list of the API flaws we find most often.
6. Leftovers from development
Debug logging, test endpoints, verbose error messages and WebViews that load untrusted content often survive into production builds. Fix: use separate build configurations and review release builds before they ship.
How to find out whether your app is affected
A mobile app penetration test checks all of the above on iOS and Android, against the OWASP MASVS standard, together with the APIs behind the app. Testing a build before launch is the cheapest moment to fix what we find.
Send us your app for a free scoping call.
