Securing E-Banking Android Apps: Checklist & Tools

The rapid growth of mobile banking apps has revolutionized the way we manage our finances. However, with convenience comes the risk of cyberattacks targeting these apps. Ensuring the security of Android e-banking apps is critical for both developers and users. This post explores a robust checklist and the essential tools needed to secure Android e-banking apps.

TL;DR

• App Shielding
• Obfuscation & Shrinking
• SSL Pinning
• Biometrics
• Secure Data Storage
• Root Protection
• Screenshot Detection
• Session Timeout Protection

Why is Security Crucial for E-Banking Apps?

E-banking apps process sensitive user data, including personal identification information (PII), account credentials, and transaction details. Any vulnerability can lead to:

• Data breaches
• Financial theft
• Loss of customer trust
• Legal and regulatory penalties

1. App Shielding

App shielding provides runtime protection by defending your app against tampering and reverse engineering.

Key Features:

• Runtime Detection: Monitors the app for malicious behavior or environment changes during execution.
• Anti-Debugging Measures: Prevents attackers from using debugging tools to analyze your app.
• Tamper Detection: Detects and reacts to unauthorized modifications.

Tools for App Shielding:

• DexGuard: Offers advanced app shielding for Android apps.
• OneSpane:  a commercial platform for shielding Android apps with no code changing required

2. Obfuscation and Shrinking

Obfuscation makes your code harder to read and reverse-engineer, while shrinking reduces app size by removing unused code.

Key Practices:

• Code Obfuscation: Rename variables, classes, and methods to make the code incomprehensible to attackers.
• Resource Obfuscation: Hide sensitive resources like API keys and configurations.
• Shrinking: Remove unused libraries and dead code to reduce the attack surface.

Tools for Obfuscation and Shrinking:

• Android R8 : is the default code shrinker and obfuscation tool in Android Studio. It combines the functionalities of ProGuard with additional optimization and performance benefits.

How to Enable R8 in Your Android Project:

1. Open your project’s build.gradle file.
2. Ensure you are using minifyEnabled true in the release build type:

buildTypes {
    release {
        minifyEnabled true
        shrinkResources true 
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}

3. Customize rules in the proguard-rules.pro file for finer control over what to obfuscate or exclude from shrinking.

3. SSL Pinning & Tools for SSL Validation

SSL pinning ensures your app communicates only with trusted servers by validating their certificates.

Benefits:

• Prevents man-in-the-middle (MITM) attacks.
• Ensures secure communication with backend servers.

Implementation Steps:

1. Pinning Certificates: Embed server certificates or public keys directly in the app.
2. Validation: Check the server's certificate against the pinned certificate.

Tools to Check SSL:

• HttpCanary : A powerful packet capture and analysis tool designed for Android by inspecting HTTPS traffic and test the effectiveness of SSL pinning in your app.
• Charles Proxy: Helps test and monitor HTTPS traffic.

4. Biometrics

Biometrics add an extra layer of security by using fingerprint, facial recognition, or iris scanning for authentication.

Benefits:

• Strong, non-replicable authentication.
• Improved user experience with faster logins.

Implementation with Android:

• Use BiometricPrompt API to implement fingerprint and face recognition.
• Ensure biometric data is processed securely and never stored outside trusted hardware like Trusted Execution Environment (TEE).

5. Secure Data Storage and Encryption

Sensitive data must be stored securely to prevent unauthorized access, even if the device is compromised.

Best Practices:

• Use Encrypted Storage: Leverage Android’s EncryptedSharedPreferences and file encryption APIs.
• Avoid Storing Credentials: Use secure tokens like OAuth or JWT instead.
• Encrypt Sensitive Data: Use AES-256 encryption for local data storage.

6. Root Protection

Rooted devices bypass the default Android security model, exposing apps to malicious software.

Root Detection Techniques:

• Check Build Properties: Detect signs of rooting tools like Magisk.
• Look for Superuser Apps: Scan for apps that manage root access.
• Monitor File System Changes: Identify modifications in system directories.

Tools:

• RootBeer Library: Provides simple root detection capabilities.

7. Screenshot Detection

Preventing screenshots or screen recordings helps protect sensitive app content.

Implementation:

• FLAG_SECURE: Add this flag in your app’s activity to block screenshots and screen recordings:

window.setFlags(WindowManager.LayoutParams.FLAG_SECURE, WindowManager.LayoutParams.FLAG_SECURE)

Benefits:

• Protects sensitive information from being captured by third-party apps.
• Safeguards against shoulder-surfing attacks.

8. Session Timeout Protection

Session timeout ensures that user sessions are automatically logged out after a period of inactivity, reducing risks of unauthorized access.

Best Practices:

• Set Inactivity Thresholds: Define reasonable timeout durations based on use cases.
• Require Re-Authentication: Prompt the user to log in again after a session expires.
• Implement Token Expiry: For token-based apps, ensure short-lived tokens with refresh mechanisms.

Final Thoughts

Each of these security features—when implemented correctly—fortifies your Android e-banking app against a wide range of attacks. With cyber threats evolving daily, adopting these measures isn’t optional; it’s a necessity for protecting both users and their finances.

Ready to Implement?

If you have questions about any specific technique or need help with implementation, let’s discuss in the comments!