Mobile Security

Organized by the OWASP MASVS categories. Apply the general checks below, then the reference for the detected stack. In cross-platform apps, also apply the Android and iOS references to the native folders.

1. Pick the reference

Project	Read
Flutter	references/flutter.md
Native Android (Kotlin/Java), or android/ in any app	references/android.md
Native iOS (Swift/Objective-C), or ios/ in any app	references/ios.md
React Native or Expo	references/react-native.md
Kotlin Multiplatform shared code and platform implementations	references/kotlin-multiplatform.md
OAuth 2.0 / OIDC login, PKCE, tokens and biometric gating, on any stack	references/auth.md

Firebase-specific protection (security rules, App Check) is covered by mobile-firebase.

For implementing identity/session transitions, use mobile-auth. For consent, SDK collection and account/data deletion, use mobile-privacy. Keep this skill focused on the security properties of those flows.

2. Evidence and severity

Every finding needs evidence in the code or configuration at file:line. Severity:

• Critical: exposed credential or sensitive data, TLS validation disabled, exported component that performs a privileged action, backend authorization missing.
• High: token in insecure storage, cleartext traffic to the API, WebView with a JavaScript bridge exposed to remote content, deep link acting without validation.
• Medium/Low: missing hardening, verbose logs, backup enabled without need, missing screenshot protection.

3. General checks (all stacks)

MASVS-STORAGE

• Access token, refresh token and personal data kept in insecure storage (preferences, plain files, unencrypted database) instead of the Keychain or Keystore-backed storage.
• Sensitive data in logs, analytics events or crash reports.

MASVS-CRYPTO

• Private API keys, client secrets, signing keys or passwords in source code, assets or bundled configuration. Everything shipped in the app can be extracted; a real secret stays on the backend.
• Homemade cryptography, fixed IV or key, MD5/SHA-1 for passwords.

MASVS-AUTH

• Authorization decided only on the client (a local isAdmin flag, hiding a button as access control).
• Sessions without expiration, or refresh tokens never invalidated on logout.
• Biometrics used only as a local boolean, without unlocking a key in the Keychain or Keystore.

For anything involving a login flow — OAuth 2.0, OpenID Connect, PKCE, redirect URIs, token rotation or biometric-gated keys — read references/auth.md before reviewing the stack reference.

MASVS-NETWORK

• http:// URLs for APIs.
• Certificate validation disabled or overridden to accept everything.
• Pinning, if present, without a rotation strategy (a single pin with no backup).

MASVS-PLATFORM

• Deep links and universal/app links that perform actions without validating parameters or without authentication.
• WebViews loading remote content with JavaScript and a native bridge enabled.
• Sensitive data on the clipboard or visible in the app switcher snapshot.

MASVS-CODE / RESILIENCE

• Release builds without obfuscation or minification when the app has sensitive logic.
• Debug code, test endpoints or feature flags that bypass checks reachable in release.
• Dependencies with known vulnerabilities, or abandoned security-sensitive libraries.

MASVS-PRIVACY

• Permissions requested without real use in the code.
• Third-party SDKs collecting data that is not declared (privacy manifest and App Store privacy details on iOS, Data safety on Google Play).

4. Useful commands (read-only)

# Signing material and environment files that should not be in the repository
git ls-files | grep -Ei '\.(jks|keystore|p12|p8|pem|mobileprovision)$|key\.properties|(^|/)\.env(\.|$)'

# Android manifest flags worth reading in context
grep -rn --include='AndroidManifest.xml' -E 'usesCleartextTraffic|allowBackup|exported="true"|debuggable' . 2>/dev/null

# iOS App Transport Security exceptions
grep -rn --include='*.plist' 'NSAllowsArbitraryLoads' . 2>/dev/null

google-services.json and GoogleService-Info.plist identify a Firebase project and ship in every app; committing them is not a leak by itself. The findings there are unrestricted API keys and weak security rules.

Output

Report under Security (or Critical, when the severity is Critical), with the MASVS category, file:line, impact and fix.