Mobile Application Security Testing: Complete Guide 2025

Mobile applications have become central to how we interact with digital services, handling sensitive personal data, financial transactions, and business-critical operations. With billions of mobile apps in use worldwide, securing mobile applications has never been more important.

This comprehensive guide covers everything you need to know about mobile application security testing, including iOS and Android-specific testing methodologies, common vulnerabilities, and best practices for securing mobile applications.

What is Mobile Application Security Testing?

Mobile application security testing is the process of evaluating mobile applications (iOS, Android, and hybrid apps) for security vulnerabilities, data protection issues, and potential attack vectors. It involves both static and dynamic analysis techniques to identify security weaknesses that could compromise user data or application functionality.

Mobile security testing helps organizations:

• Protect sensitive user data stored on mobile devices
• Prevent unauthorized access to application functionality
• Ensure secure communication between apps and backend services
• Comply with data protection regulations (GDPR, CCPA, etc.)
• Maintain user trust and brand reputation

Mobile Application Security Testing Types

1. Static Application Security Testing (SAST)

SAST analyzes source code and compiled binaries without executing the application:

• Source code analysis for security vulnerabilities
• Binary analysis for compiled applications
• Dependency scanning for vulnerable libraries
• Configuration file analysis

2. Dynamic Application Security Testing (DAST)

DAST tests running applications in real-time:

• Runtime behavior analysis
• Network traffic interception and analysis
• API security testing
• Authentication and authorization testing

3. Interactive Application Security Testing (IAST)

IAST combines static and dynamic analysis for comprehensive coverage:

• Real-time vulnerability detection
• Code coverage analysis
• Accurate vulnerability identification

4. Manual Penetration Testing

Manual testing by security experts provides deep analysis of complex vulnerabilities:

• Business logic testing
• Reverse engineering and code analysis
• Advanced attack techniques
• Social engineering testing

OWASP Mobile Top 10 Vulnerabilities

The OWASP Mobile Top 10 identifies the most critical security risks in mobile applications:

M1: Improper Platform Usage

Misuse of platform features or security controls:

• Incorrect use of TouchID, Keychain, or Android Keystore
• Improper implementation of platform security controls
• Misuse of platform APIs

Example: Insecure Keychain Usage (iOS)

// VULNERABLE: Storing sensitive data without proper protection
let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrAccount as String: "userToken",
    kSecValueData as String: token.data(using: .utf8)!
]
SecItemAdd(query as CFDictionary, nil)

// SECURE: Using proper access control
let query: [String: Any] = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrAccount as String: "userToken",
    kSecValueData as String: token.data(using: .utf8)!,
    kSecAttrAccessControl as String: SecAccessControlCreateWithFlags(
        nil,
        kSecAttrAccessibleWhenUnlockedThisDeviceOnly,
        .biometryAny,
        nil
    )!
]
SecItemAdd(query as CFDictionary, nil)

M2: Insecure Data Storage

Storing sensitive data insecurely on the device:

• Plaintext storage of credentials, tokens, or PII
• Insecure file permissions
• Logging sensitive information

Example: Insecure Data Storage (Android)

// VULNERABLE: Storing credentials in SharedPreferences
SharedPreferences prefs = getSharedPreferences("app_prefs", MODE_PRIVATE);
prefs.edit().putString("password", userPassword).apply();
// Data stored in plaintext XML file

// SECURE: Using Android Keystore for encryption
KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);
KeyGenerator keyGenerator = KeyGenerator.getInstance(
    KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
keyGenerator.init(new KeyGenParameterSpec.Builder(
    "MyKeyAlias",
    KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
    .setBlockModes(KeyProperties.BLOCK_MODE_GCM)
    .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
    .build());
keyGenerator.generateKey();

// Encrypt data before storage
Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, keyStore.getKey("MyKeyAlias", null));
byte[] encryptedData = cipher.doFinal(sensitiveData.getBytes());

M3: Insecure Communication

Insufficient protection of data in transit:

• Missing or weak SSL/TLS implementation
• Certificate pinning bypass vulnerabilities
• Cleartext communication

Example: SSL Pinning Implementation

// iOS: Certificate Pinning with NSURLSession
class PinningDelegate: NSObject, URLSessionDelegate {
    func urlSession(_ session: URLSession, 
                   didReceive challenge: URLAuthenticationChallenge,
                   completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        
        guard let serverTrust = challenge.protectionSpace.serverTrust else {
            completionHandler(.cancelAuthenticationChallenge, nil)
            return
        }
        
        // Load pinned certificate
        let pathToCert = Bundle.main.path(forResource: "certificate", ofType: "cer")!
        let localCertificate = NSData(contentsOfFile: pathToCert)!
        let pinnedCert = SecCertificateCreateWithData(nil, localCertificate)!
        
        // Verify certificate
        let policies = [SecPolicyCreateSSL(true, challenge.protectionSpace.host as CFString)]
        SecTrustSetPolicies(serverTrust, policies as CFTypeRef)
        
        var result: SecTrustResultType = .invalid
        SecTrustEvaluate(serverTrust, &result)
        
        if result == .unspecified || result == .proceed {
            completionHandler(.useCredential, URLCredential(trust: serverTrust))
        } else {
            completionHandler(.cancelAuthenticationChallenge, nil)
        }
    }
}

M4: Insecure Authentication

Weak authentication mechanisms:

• Biometric authentication bypass
• Weak session management
• Insecure token storage

M5: Insufficient Cryptography

Weak or improper use of cryptography:

• Weak encryption algorithms (DES, MD5, SHA-1)
• Hardcoded encryption keys
• Improper key management

M6: Insecure Authorization

Authorization flaws allowing unauthorized access:

• Client-side authorization checks
• Missing authorization on sensitive operations
• Privilege escalation vulnerabilities

M7: Client Code Quality

Code-level vulnerabilities:

• Buffer overflows
• Injection vulnerabilities
• Memory corruption issues

M8: Code Tampering

Lack of protection against code modification:

• Missing code obfuscation
• Insufficient anti-tampering controls
• Lack of runtime application self-protection (RASP)

M9: Reverse Engineering

Insufficient protection against reverse engineering:

• Lack of code obfuscation
• Exposed sensitive logic
• Readable application structure

Android Reverse Engineering Example

# Using APKTool to reverse engineer Android app
apktool d app.apk
# Decompiles APK to readable Smali code

# Using jadx to decompile to Java
jadx -d output app.apk
# Produces readable Java source code

# Using Frida for runtime manipulation
frida -U -f com.example.app -l script.js
# Hooks into running app to modify behavior

M10: Extraneous Functionality

Hidden or debug functionality left in production:

• Debug endpoints
• Test accounts
• Backdoor functionality

Manual testing by security experts identifies complex vulnerabilities:

• Business logic flaws
• Authentication bypasses
• Reverse engineering and tampering
• Runtime manipulation

iOS Application Security Testing

iOS-Specific Security Considerations

• App Transport Security (ATS): Verify HTTPS enforcement and certificate pinning
• Keychain Security: Test secure storage of sensitive data
• Code Signing: Verify proper code signing and provisioning
• Jailbreak Detection: Test for jailbreak detection mechanisms
• Runtime Protection: Assess anti-tampering and anti-debugging measures

Common iOS Vulnerabilities

• Insecure Data Storage: Sensitive data stored in plaintext
• Weak Cryptography: Use of deprecated or weak encryption algorithms
• Insecure Communication: Unencrypted or improperly encrypted network traffic
• Insecure Authentication: Weak authentication mechanisms or session management
• Insufficient Authorization: Missing or weak authorization checks
• Client-Side Injection: SQL injection, XSS, or other injection vulnerabilities
• Security Decisions via Untrusted Input: Security decisions based on user input
• Improper Error Handling: Information disclosure through error messages
• Use of Hardcoded Credentials: Hardcoded API keys, passwords, or tokens
• Insufficient Transport Layer Protection: Weak SSL/TLS configuration

iOS Testing Tools

• MobSF (Mobile Security Framework): Automated mobile app security testing
• Frida: Dynamic instrumentation toolkit
• class-dump: Objective-C runtime information extraction
• Hopper: Reverse engineering tool
• Keychain-Dumper: Keychain data extraction

Android Application Security Testing

Android-Specific Security Considerations

• APK Security: Verify APK signing and integrity
• Manifest Security: Review AndroidManifest.xml for security issues
• Permission Model: Test for excessive or unnecessary permissions
• Root Detection: Assess root detection mechanisms
• ProGuard/R8: Verify code obfuscation and minification
• Deep Link Security: Test deep link handling and validation

Common Android Vulnerabilities

• Insecure Data Storage: Unencrypted storage of sensitive data
• Insecure Communication: Unencrypted network traffic or weak SSL/TLS
• Insecure Cryptographic Storage: Weak encryption implementation
• Unintended Data Leakage: Data leakage through logs, cache, or backups
• Poor Authorization and Authentication: Weak authentication mechanisms
• Broken Cryptography: Use of weak or deprecated cryptographic functions
• Client-Side Injection: SQL injection, XSS, or command injection
• Security Decisions via Untrusted Input: Security decisions based on user input
• Improper Session Handling: Weak session management
• Lack of Binary Protections: Missing anti-tampering and anti-debugging

Android Testing Tools

• MobSF (Mobile Security Framework): Automated security testing
• APKTool: Reverse engineering Android applications
• Frida: Dynamic instrumentation
• Drozer: Android security assessment framework
• Burp Suite: Network traffic interception and analysis
• ADB (Android Debug Bridge): Device communication and debugging

Mobile Application Security Testing Methodology

Phase 1: Information Gathering

• Analyze application metadata and manifest files
• Identify third-party libraries and dependencies
• Review application architecture and design
• Map application functionality and user flows
• Identify API endpoints and backend services

Phase 2: Static Analysis

• Source code review (if available)
• Binary analysis and reverse engineering
• Configuration file analysis
• Dependency vulnerability scanning
• Hardcoded credential identification

Phase 3: Dynamic Analysis

• Runtime behavior analysis
• Network traffic interception
• API security testing
• Authentication and authorization testing
• Data storage analysis

Phase 4: Reverse Engineering and Tampering

• Application decompilation and analysis
• Runtime manipulation testing
• Anti-tampering bypass testing
• Code injection and modification testing

Phase 5: Reporting

• Document all findings with detailed descriptions
• Provide risk ratings and CVSS scores
• Include proof-of-concept examples
• Recommend remediation steps
• Prioritize vulnerabilities by severity

OWASP Mobile Top 10 Vulnerabilities

The OWASP Mobile Top 10 provides a framework for mobile app security testing:

1. Improper Platform Usage: Misuse of platform features or security controls
2. Insecure Data Storage: Unencrypted or improperly encrypted sensitive data
3. Insecure Communication: Weak or missing encryption for network traffic
4. Insecure Authentication: Weak authentication mechanisms
5. Insufficient Cryptography: Weak cryptographic implementation
6. Insecure Authorization: Missing or weak authorization checks
7. Client Code Quality: Code quality issues leading to vulnerabilities
8. Code Tampering: Lack of anti-tampering protections
9. Reverse Engineering: Insufficient code obfuscation
10. Extraneous Functionality: Hidden features or debug code in production

Best Practices for Mobile Application Security Testing

1. Test on Real Devices

While emulators are useful, testing on real devices provides more accurate results:

• Test on multiple device models and OS versions
• Test on both rooted/jailbroken and non-rooted devices
• Test on different network conditions

2. Test Both Static and Dynamic Aspects

Combine static code analysis with dynamic runtime testing for comprehensive coverage.

3. Focus on Data Protection

Mobile apps handle sensitive data. Ensure proper encryption and secure storage:

• Verify encryption at rest and in transit
• Test secure key management
• Verify secure deletion of sensitive data

4. Test Authentication and Authorization

Verify robust authentication and authorization mechanisms:

• Test for authentication bypasses
• Verify session management
• Test authorization checks at all levels

5. Test Network Security

Ensure secure communication with backend services:

• Verify certificate pinning
• Test SSL/TLS configuration
• Verify API security

Compliance and Regulatory Requirements

Mobile application security testing helps meet various compliance requirements:

• GDPR: Requires security measures to protect personal data
• CCPA: California Consumer Privacy Act requirements
• HIPAA: Healthcare data protection requirements
• PCI DSS: Payment card data protection for mobile payment apps
• OWASP MASVS: Mobile Application Security Verification Standard

Conclusion

Mobile application security testing is essential for protecting user data and maintaining application security. By combining automated scanning with manual penetration testing, organizations can identify and remediate vulnerabilities before they can be exploited.

Remember that mobile security is an ongoing process. Regular security assessments, continuous monitoring, and prompt remediation are essential for maintaining a strong security posture in the mobile threat landscape.