Mobile Security

Scope

End-to-end mobile application VAPT for Android (APK/AAB) and iOS (IPA), aligned to the OWASP MASVS v2.x control groups and the MASTG testing process. Four complementary tiers:

1. Static reverse engineering of compiled artifacts — Dart AOT snapshots, Unity IL2CPP, React Native/Hermes bytecode, native ARM64 .so/Mach-O, smali. Recover secrets, endpoints, and the crypto contract without a device.
2. SAST — manifest / Info.plist, exported-component & IPC surface, WebView, local storage, cryptographic-primitive weakness, code-signing, and automated baseline (MobSF/apkid/apkleaks) → then manual deep-dive.
3. Dynamic analysis (DAST) — Frida/objection instrumentation, traffic interception, TLS-pinning bypass across stacks, Keychain/Keystore runtime dumps, IPC probing, and root/jailbreak/anti-tamper defeat for MAS-L2 / MASA scope.
4. Privacy — data-collection inventory, tracker/SDK enumeration, PII leakage, declared-vs-actual (Play Data Safety / Apple Privacy Manifest).

Static dump first (faster, no device); dynamic is a first-class phase whenever a control can only be proven at runtime (enforced pinning, Keystore-backed keys, root reaction, IPC guards). Cross-asset stitching, scoring, and reporting are owned by sibling skills — this skill produces MASVS/MASTG-tagged findings and hands them off.

Coverage contract

In a coverage-mode engagement (pentest-engagement mobile mode) completion is code-enforced, not narrative. Two surfaces are gated, and both are mandatory:

Surface	File	Classes
The app bundle	recon/inventory/mobile-surface.json	the 15 MAS-* MASVS classes
The backend recovered from the bundle	<apex>-api/recon/inventory/surface.json	the ordinary OWASP API/web classes

The second row is where the material risk has historically been. A decompiled bundle hands you the full server contract, and that surface is not browser-reachable — so it is systematically under-tested by everyone, including the app's own developers. Recovering the endpoint inventory and driving it through the API classes is not an optional extra; a bundle that yields zero endpoints is treated as a failed acquisition.

Per-class detail: reference/masvs-class-map.md. Two rules worth internalising before you write a negative:

• proof_mode: runtime cannot be closed statically. Pinning and root detection are the classic traps: static analysis can prove a control is inert (a CertificatePinner built and never attached, a RootBeer that no DEX references) — raise that as a positive. It can never prove the control is effective; that needs a bypass attempt that failed, and a failed bypass is a legitimate, reportable result.
• proof_mode: static can never be device-deferred. No device does not excuse the manifest, the signature, the bundled dependencies, or the secrets in the artifact.

When to use

• Target ships an Android APK/AAB or iOS IPA — extract and inspect before any runtime testing.
• Built with Flutter (lib/arm64-v8a/libapp.so / iOS App.framework), Unity (libil2cpp.so + global-metadata.dat), or React Native + Hermes (libhermes.so + index.android.bundle) — needs a runtime-aware decompiler, not just jadx.
• Stock Android/iOS app — you need the manifest/IPC/storage/crypto/signing attack surface (SAST) and, where a control is runtime-only, dynamic confirmation.
• App uses encrypted API envelopes (KEY/IV/SALT/SIGNATURE headers) and you need to reverse the crypto contract, then replay against the live API.
• TLS pinning / root / jailbreak detection blocks testing — bypass it dynamically (or defeat it statically) and demonstrate the protected flow.
• You suspect IDOR / mass assignment / business-logic flaws easier to find in the dumped client, then confirmed server-side.
• You need a MASVS-PRIVACY pass (trackers, over-collection, PII leakage, declared-vs-actual).

Methodology

Start at reference/methodology.md — the phase backbone (ACQUIRE → TRIAGE → STATIC → DYNAMIC → NETWORK → STORAGE → PLATFORM/IPC → BACKEND PIVOT → REPORT), app acquisition + evidence integrity, the MASVS→file coverage map, finding-tagging convention, and the client→API pivot. It routes to every reference below. Do preflight (../coordination/reference/preflight-checklist.md) first.

References

Cross-cutting

• reference/methodology.md — the hub: phases, acquisition (adb pull / bundletool / ipatool), MASVS/MASTG tagging, backend pivot.
• reference/privacy-testing.md — MASVS-PRIVACY for both platforms: trackers/SDKs, PII channels, declared-vs-actual.

Android

• reference/android-static-analysis.md — SAST: MobSF/apkid/apkleaks baseline, manifest & exported-component/IPC, ContentProvider SQLi/traversal, PendingIntent, deep links, native WebView RCE, storage & Keystore review, crypto-primitive weakness pass, NSC, apksigner/Janus, SBOM.
• reference/android-dynamic-analysis.md — DAST: device/Magisk/Zygisk setup, frida-server bring-up, objection recipes, interception + Android-7 user-CA workarounds, cross-stack pinning bypass (OkHttp/BoringSSL-Flutter/RN), drozer IPC, runtime storage, RESILIENCE active bypass + repack/resign.

iOS

• reference/ios-static-analysis.md — SAST: IPA acquisition + FairPlay decrypt (cryptid), Mach-O/ObjC/Swift RE, ATS, entitlements/provisioning, binary hardening, Keychain accessibility + Data Protection, URL schemes/Universal Links, WKWebView, pasteboard/snapshot, MobSF/SBOM.
• reference/ios-dynamic-analysis.md — DAST: jailbroken vs non-JB (objection patchipa / frida-gadget) bring-up, objection/Frida on iOS, SSL Kill Switch / SecTrust pinning bypass, Keychain dump, LAContext biometric bypass, jailbreak/anti-debug defeat, method tracing.

Framework-specific reverse engineering

• reference/flutter-aot-reversing.md — Flutter/Dart AOT with blutter; HTTP crypto-envelope patterns (fast_rsa OAEP-SHA256 + AES-256-CBC) and the weaknesses to report.
• reference/scenarios/android/react-native-hermes.md — RN+Hermes: HBC-version check, decompile index.android.bundle with hermes-dec, BuildConfig secret fast-path, RN-specific MASVS surface.
• reference/scenarios/android/native-lib-host-extraction.md — host-side dlopen of an Android .so with a Bionic→glibc forwarder + strcmp/memcmp interceptor (no Frida/emulator).

Cross-skill (reused capabilities — cross-linked, not duplicated)

• ../reverse-engineering/reference/scenarios/static-analysis/unity-il2cpp-recipe.md — Unity libil2cpp.so + global-metadata.dat dump (Il2CppDumper/Il2CppInspector).
• ../reverse-engineering/reference/scenarios/dynamic-analysis/frida-hooking.md — Frida hooking primitives (spawn/attach, Interceptor, Stalker, Java.perform, ObjC hooks) used by both dynamic files.
• ../reverse-engineering/reference/scenarios/obfuscation/packed-binaries.md — packer / anti-analysis unpacking for obfuscated APKs/.so.
• ../reverse-engineering/reference/scenarios/obfuscation/hash-dispatcher-chain.md — Z3 over polynomial-hash dispatcher chains in a native .so.
• ../api-security/reference/scenarios/rest/owasp-bola-bopla.md · ../api-security/reference/scenarios/rest/mass-assignment.md — the client→API pivot for endpoints/IDOR recovered from the client.

Deterministic control-wiring detector

• ../../tools/apk_control_wiring.py — static cross-reference over a decompiled Android tree that distinguishes a REAL applied control from an ORPHANED one: RootBeer/SafetyNet/Play-Integrity shipped-but-unwired (referenced but the result gates nothing), CertificatePinner built-but-not-attached to an OkHttpClient, hardcoded AES/DES key literals + their invoke-sites, and bundled-but-never-loaded .so. Run it in the STATIC phase BEFORE authoring remediation verdicts — a naive re-test that only greps for the control's presence wrongly reports an inert control "fixed" (a recurring mobile re-test crux).

Anti-patterns

• Reaching for Frida/emulator before the static dump exists — static-first is faster and needs no device. But do not treat dynamic as out of scope: pinning enforcement, Keystore binding, root reaction, and IPC reachability are runtime-only.
• Reporting a control as present (root/pinning/tamper detection) without an active bypass attempt — MAS-L2 / MASA require you defeat it or prove you can't.
• Concluding "no pinning" from an empty network_security_config.xml, or "no secrets" from a cryptid 1 iOS binary — check the JS/native pin layers, and decrypt the IPA first.
• Stopping at a client-side IDOR — it is a server-side hypothesis; confirm via the api-security pivot.
• Reporting a CVE from a library's mere presence — confirm the exact version and a reachable code path.