Skill: Mobile Security

Supplementary Files:

• payloads.md — Complete mobile security attack/defense chain payloads (APK/IPA analysis, Frida hooks, SSL bypass, storage extraction, Intent attacks, etc.)
• test-cases.md — Structured test cases (static analysis, dynamic analysis, runtime manipulation, network testing, data protection)

Summary

Mobile Security skill domain covering mobile operations.

Tools: frida, objection, apktool, jadx, mobsf, drozer

Domain: mobile

Description

Mobile security covers the complete attack/defense chain of Android/iOS application security testing, APK/IPA reverse engineering, runtime manipulation, certificate pinning bypass, and mobile data protection. The core objective is to identify security flaws in mobile applications, assess client-side defense strength, extract sensitive data, and develop hardening strategies.

Mastering this skill requires a deep understanding of Android APK structure (DEX, Manifest, Resources), iOS IPA structure (Mach-O, Info.plist), mobile sandbox mechanisms, Keychain/Keystore secure storage, and Frida dynamic instrumentation. The agent can comprehensively use tools such as apktool, jadx, Frida, objection, and MobSF to complete the full workflow from application decompilation to runtime manipulation.

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Use Cases

1. Android/iOS Application Penetration Testing - Perform security assessments on target mobile applications, discovering vulnerabilities such as data leakage, insecure storage, and exposed components
2. APK Reverse Engineering and Code Audit - Decompile Android applications, auditing source code for hardcoded credentials, insecure API calls, and logic flaws
3. SSL Pinning Bypass - Bypass application certificate pinning mechanisms to intercept and analyze encrypted HTTPS traffic
4. Runtime Hooking and Data Extraction - Use Frida for dynamic instrumentation of running applications, hooking encryption functions, bypassing security checks, and extracting sensitive data from memory
5. Mobile Malware Analysis - Analyze behavioral characteristics of suspicious APKs/IPAs, extract IoCs, and assess threat levels

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Core Tools

Tool	Purpose	Command Example
frida	Dynamic instrumentation framework, runtime hooks, function tracing, memory read/write	frida -U -f com.target.app -l hook.js
objection	Frida-based mobile runtime exploration toolkit	objection -g com.target.app explore
apktool	APK decompilation and repackaging, restoring Manifest and smali	apktool d app.apk -o app_source
jadx	DEX decompilation to readable Java source code	jadx app.apk -d app_java
mobsf	Mobile application automated security analysis framework (static + dynamic)	docker run -p 8000:8000 opensecurity/mobsf
drozer	Android IPC vulnerability scanning and exploitation framework	drozer console connect

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Methodology

Attack Chain

App Decompilation     Static Analysis       Dynamic Analysis     Runtime Manipulation
(apktool, jadx)     (Code audit, Manifest) (Proxy, traffic)   (Frida, objection)
      |                 |                 |                |
      v                 v                 v                v
Information          Vulnerability      Communication        Data Extraction
Collection           Identification     Analysis             & Exploitation
(Package name,      (Hardcoded         (API endpoints,     (Sensitive data
 components,         credentials,       authentication       export,
 permissions, SDK)   exported            mechanisms,         auth bypass,
                       components,       SSL Pinning)        security check
                       insecure                              bypass)
                       storage)

1. App Decompilation - apktool restores Manifest and smali code, jadx decompiles to readable Java, obtaining complete application structure
2. Static Analysis - Audit AndroidManifest.xml (exported components, permissions, debuggable flag), scan for hardcoded credentials and API keys
3. Dynamic Analysis - Configure proxy to intercept network traffic, analyze API communication patterns and authentication mechanisms, identify certificate pinning implementations
4. Runtime Manipulation - Use Frida to hook key functions (encryption, authentication, checks), bypass security protections, extract runtime sensitive data
5. Data Extraction and Exploitation - Export plaintext data from SharedPreferences/SQLite, exploit exported component vulnerabilities, construct Intent attack chains

Defense Perspective

Defense Measure	Purpose	Bypass Approach
Code Obfuscation	ProGuard/R8 obfuscate code, increasing reverse engineering difficulty	Spend time analyzing obfuscation mappings, dynamically hook to bypass static protections
Certificate Pinning	Pin server certificate fingerprints, preventing MITM attacks	Frida hook TrustManager / OkHttp CertificatePinner
Root/Jailbreak Detection	Detect whether device is rooted/jailbroken, blocking dangerous environments	Frida hook detection function return values, modify file existence checks
Anti-Tampering	Detect APK integrity, prevent repackaging	Modify signature verification logic, bypass integrity checks
Secure Storage	Use Android Keystore / iOS Keychain for sensitive data storage	Hook encryption functions to intercept plaintext before encryption / after decryption
Anti-Debug	Detect debugger attachment, preventing dynamic analysis	Modify anti-debugging flags, use Frida spawn mode to bypass

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Practical Steps

1. APK Decompilation and Static Analysis

Decompile APK to obtain Manifest and smali code, scan for hardcoded credentials and insecure storage patterns.

2. Frida Hook Basics

Use Frida Java.perform to hook login methods for credential interception, hook encryption functions to intercept plaintext data.

3. SSL Pinning Bypass

Bypass certificate pinning through Frida hooking OkHttp CertificatePinner or replacing TrustManager. Shortcut: objection -g com.target.app explore -> android sslpinning disable.

4. Data Storage Analysis

Check SharedPreferences plaintext storage, SQLite database contents, external storage leakage, exploit allowBackup to extract application data.

5. Intent Exploitation and Component Attacks

Use drozer to discover exported components, construct malicious Intents via adb to attack exported Activities, Content Providers, Broadcast Receivers, and Deep Links.

Detailed payloads in payloads.md, complete test checklist in test-cases.md.

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Cross-Platform Mobile Testing

Modern mobile apps increasingly use cross-platform frameworks that introduce unique attack surfaces:

Framework	Key Attack Surface	Primary Tools
React Native	JS bundle extraction, WebView bridges, AsyncStorage	jadx, Frida, Burp
Flutter	Dart snapshot, libapp.so, platform channels	Ghidra, Frida, reFlutter
Xamarin	DLL extraction, AOT compilation	dnSpy, ILDasm
Capacitor/Ionic	WebView exposure, plugin API	Chrome DevTools, Burp

See guides/react-native-flutter-security.md for framework-specific testing methodology.

Mobile-Cloud Integration Testing

Mobile apps connect to cloud backends (Firebase, AWS Amplify, custom APIs). Key test areas:

1. Backend API exposure: Enumerate and test all API endpoints accessible from the app
2. Cloud service misconfiguration: Firebase rules, Cognito pools, Storage buckets
3. Authentication flow: OAuth 2.0/OIDC implementation flaws on mobile
4. Third-party SDK security: Data collection, tracking, insecure defaults

See guides/mobile-api-security-testing.md and guides/mobile-cloud-integration.md.

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Detection Methods

Mobile App Static Analysis

• Hardcoded secrets: Strings analysis revealing API keys (AKIA...), JWT tokens, OAuth client secrets.
• Insecure storage: Credentials in SharedPreferences (Android), NSUserDefaults (iOS) without encryption.
• Exported components (Android): Activities/services/receivers exported without permission check.
• Insecure transit: Apps not enforcing TLS; cleartext traffic allowed.

Dynamic Analysis Detection

• Runtime manipulation: Frida-instrumented app accessing sensitive functions.
• Insecure IPC: Apps sharing sensitive data via Intent (Android) / URL scheme (iOS) without verification.
• WebView abuse: JavaScript bridge (addJavascriptInterface) exposing sensitive functions.

SIEM Detection Rules

• Splunk SPL (mobile): index=mobile sourcetype=apk:analysis | where permission matches "android.permission.SMS"
• MobSF (Mobile Security Framework): Automated static + dynamic analysis.
• NowSecure / Veracode Mobile: Commercial mobile app scanning.

Defense Evasion Techniques

Mobile Exploit Stealth

• Single-shot exploit: One exploit per app launch; below sustained-pattern detection.
• Memory-only execution: Run from RAM; no disk artifacts in /data/data/<package>/.
• Use legitimate intents: Abuse exported components that look legitimate (e.g., share, profile).

Anti-Analysis

• Root/Jailbreak detection: Detect and exit if compromised (defender-side; red team needs to bypass).
• Frida/Xposed detection: Check for Frida server on port 27042; check for Xposed hooks.
• Emulator detection: Check for emulator-specific properties (ro.kernel.qemu, iSimulator).
• SafetyNet / Play Integrity: Google's remote attestation; harder to bypass.

Persistence Stealth

• Device admin (Android): Use Device Admin for persistence; harder to remove.
• Accessibility service (Android): Use Accessibility for persistence; powerful and persistent.
• Background app refresh (iOS): Use Background App Refresh; killed less often.

Network Stealth

• Domain fronting: Use legitimate CDN for C2; appears as legitimate traffic.
• Protocol mimicry: C2 over legitimate-looking API (e.g., JSON to attacker's "analytics" endpoint).
• TLS fingerprinting: Match okhttp / URLSession JA3 signature.

Orchestration

ECC Loop Pattern

• Pattern: Sequential Pipeline
• Rationale: Mobile security testing follows a sequential approach — decompile → analyze → hook → verify — where each phase builds on the previous
• Integration: codebase-onboarding (app structure understanding), browser-qa (WebView testing), verification-loop (finding confirmation)

Cross-Skill Pipeline

codebase-onboarding → mobile-security → verification-loop → article-writing

Quality Gate

• Pre-condition: Target APK/IPA available, testing environment configured
• Post-condition: All attack surfaces documented, findings independently verified
• Verification: Use verification-loop Phase 4 (independent confirmation with different tool)

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Hacker Laws

Law	Application in Mobile Security
First Principles	Don't rely on tools for one-click results; understand APK internal structure (DEX, Manifest, Resources) and Android runtime mechanisms. Only by understanding the underlying principles of Frida instrumentation can you write precise hook scripts
Trust but Verify	All client-side security checks can be bypassed. Root Detection, SSL Pinning, and Anti-Debug are delays, not barriers, to attackers. Defense design must assume the client has been fully compromised
Minimize Attack Surface	Every exported=true component is an entry point. Follow the principle of least privilege: disable unnecessary exported components, remove debuggable flags, prohibit cleartext traffic, and implement Certificate Pinning

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Learning Resources

This skill's supplementary files: payloads.md, test-cases.md Related skills: skills/binary-reverse/SKILL.md, skills/web-xss/SKILL.md External resources:

• OWASP MSTG - Authoritative mobile security testing standard
• Frida Official Documentation - Complete reference for Frida dynamic instrumentation
• MobSF GitHub - Mobile security automated analysis framework
• HackTricks - Mobile Pentesting - Mobile penetration techniques collection