Mobile App Security Mistakes Every Developer Makes (And How to Fix Them)

> Quick Summary: This guide shows you the 7 most common mobile app security mistakes and exactly how to fix them. You'll learn how to protect API keys, encrypt data, use HTTPS, secure authentication, validate inputs, remove debug code, and protect your source code. Works for React Native, iOS (Swift), and Android (Kotlin).

Here's the scary truth: 83 out of 100 mobile apps have at least one security issue in 2025. Even worse? App attacks surged to 83% this year, and 60% of iOS apps have absolutely NO code protection.

Real-world damage (2025 updated):

• Over 120,000 fake apps detected across major app stores
• 703% increase in credential phishing attacks
• Cybercrime costs will exceed $23 trillion by 2027
• 44% year-over-year increase in global cyberattacks
• 60% of data breaches involve unpatched vulnerabilities

Most security problems come from 7 common mistakes. Fix these, and your app becomes 10x safer. Let's learn what they are.

---

🚀 Quick Start: Fix These 3 Things Right Now (15 Minutes)

Before reading the full guide, fix these critical issues immediately:

1. Find Hardcoded API Keys (5 min) Search your entire project for exposed secrets. If you find any, move them to environment variables NOW.

2. Check for HTTP Connections (5 min) Search your code for http:// (not https://). Replace all HTTP URLs with HTTPS to prevent data theft.

3. Scan for Vulnerabilities (5 min) Run: npm audit Then fix critical issues with: npm audit fix

Done? Great! Now let's learn why these matter and what else you need to fix.

---

Table of Contents

1. The "Vibe Coding" Problem
2. Mistake #1: Hardcoded API Keys & Secrets
3. Mistake #2: Unencrypted Data Storage
4. Mistake #3: Trusting HTTP (No HTTPS)
5. Mistake #4: Weak Authentication
6. Mistake #5: No Input Validation
7. Mistake #6: Exposing Debug Code in Production
8. Mistake #7: No Code Protection
9. Platform-Specific Quick Wins
10. Security Testing Guide
11. Pre-Launch Security Checklist
12. Frequently Asked Questions (FAQ)

The "Vibe Coding" Problem

You know the feeling. Your app finally works. The buttons click, the screens look beautiful, users are happy. Time to launch!

But wait... Did you check your security? Are passwords safe? Can hackers steal user data?

"Vibe coding" means building apps that "just work" without thinking about security. It's like building a house with beautiful furniture but forgetting to install locks on the doors.

This guide will help you fix these problems. No computer science degree needed—just simple, practical steps you can follow today.

The 7 Deadly Security Mistakes

Mistake #1: Hardcoded API Keys & Secrets

This is the #1 security mistake developers make.

Think of it like this: Putting API keys in your code is like writing your bank PIN on your credit card. Anyone who sees it can steal everything.

#### ❌ What NOT to Do

Example 1: Hardcoded API Keys (React Native)

// ❌ WRONG - Never do this!
const API_KEY = "sk-1234567890abcdef";
const STRIPE_KEY = "pk_live_XXXXXXXXXX";

export const firebaseConfig = {
  apiKey: "AIzaSyXXXXXXXXXXXXX",
  authDomain: "myapp.firebaseapp.com",
  projectId: "myapp-12345"
};

Why this is bad: Anyone can decompile your app and extract these keys.

---

Example 2: Committing .env Files to Git

# ❌ WRONG - This file should be in .gitignore!
# .env
REACT_APP_API_KEY=sk-1234567890abcdef

Why this is bad: Git history is permanent. Once committed, the secret is compromised forever.

#### ✅ What to Do Instead

Solution 1: Use Environment Variables (React Native)

Step 1: Create .env file (add to .gitignore!)

# .env
API_KEY=sk-1234567890abcdef
STRIPE_KEY=pk_live_XXXXXXXXXX

Step 2: Load in your code

// ✅ CORRECT - Load from environment variables
import Config from 'react-native-config';

const apiKey = Config.API_KEY;
const stripeKey = Config.STRIPE_KEY;

---

Solution 2: Use Backend Proxy Pattern

Never call third-party APIs directly from your mobile app. Create a backend proxy:

Mobile App Code:

// ✅ Mobile App - Only calls your backend
const response = await fetch('https://yourbackend.com/api/data');
const data = await response.json();

Backend Server Code:

// ✅ Your Backend - Keeps API keys secure
app.get('/api/data', async (req, res) => {
  const apiKey = process.env.SECRET_API_KEY;
  const data = await fetch('https://thirdparty.com/api?key=' + apiKey);
  const json = await data.json();
  res.json(json);
});

Solution 3: Use Secrets Management (Production)

• AWS Secrets Manager - Enterprise-grade secret storage
• Google Cloud Secret Manager - GCP's secure secret solution
• Azure Key Vault - Microsoft's key management service
• HashiCorp Vault - Open-source secrets management

When you publish your app to the App Store or Play Store, hackers can download it and see inside. They use simple tools to read your code like opening a zip file. If your API keys are in the code, they're stolen in minutes.

Real damage: In 2023, hackers found AWS passwords in 2,000+ apps on Google Play. They used these passwords to access private databases and steal user data.

Bottom line: Hardcoded API keys = guaranteed security breach. It's not "if" but "when."

#### 🛠️ Tools to Help:

• TruffleHog: Scan Git repositories for secrets
• GitGuardian: Monitor your repos for exposed secrets
• git-secrets: Prevent committing secrets

Mistake #2: Unencrypted Data Storage

The Problem: Storing sensitive data in plain text on the device.

Think of it like this: Storing passwords without encryption is like writing your diary in a notebook and leaving it on a park bench. Anyone can pick it up and read your secrets.

#### ❌ What NOT to Do

Example 1: Using AsyncStorage for Sensitive Data

// ❌ WRONG - AsyncStorage is NOT encrypted!
await AsyncStorage.setItem('credit_card', '4111111111111111');
await AsyncStorage.setItem('password', 'myPassword123');
await AsyncStorage.setItem('auth_token', 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...');

Why this is bad: AsyncStorage stores data in plain text. Anyone with device access can read it.

---

Example 2: Using Base64 "Encryption"

// ❌ WRONG - Base64 is NOT encryption, it's just encoding!
const encoded = btoa(sensitiveData);
await AsyncStorage.setItem('data', encoded);
// Anyone can decode this with atob()

Why this is bad: Base64 is reversible encoding, not encryption. It provides zero security.

#### ✅ What to Do Instead

Solution 1: React Native - Use Encrypted Storage

// ✅ CORRECT - Use encrypted storage
import EncryptedStorage from 'react-native-encrypted-storage';

// Store sensitive data securely
await EncryptedStorage.setItem(
  'user_session',
  JSON.stringify({
    token: authToken,
    userId: userId,
    refreshToken: refreshToken
  })
);

// Retrieve when needed
const session = await EncryptedStorage.getItem('user_session');
const data = JSON.parse(session);

---

Solution 2: React Native - Use Secure Keychain

// ✅ CORRECT - Use native keychain
import * as Keychain from 'react-native-keychain';

// Store credentials
await Keychain.setGenericPassword('username', 'password', {
  service: 'com.myapp'
});

// Retrieve credentials
const credentials = await Keychain.getGenericPassword();
if (credentials) {
  console.log(credentials.username, credentials.password);
}

---

Solution 3: Android (Kotlin) - EncryptedSharedPreferences

// ✅ CORRECT - Android encrypted storage
import androidx.security.crypto.EncryptedSharedPreferences
import androidx.security.crypto.MasterKey

val masterKey = MasterKey.Builder(context)
    .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
    .build()

val sharedPreferences = EncryptedSharedPreferences.create(
    context,
    "secure_prefs",
    masterKey,
    EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
    EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)

// Store encrypted data
sharedPreferences.edit().putString("auth_token", token).apply()

---

Solution 4: iOS (Swift) - Use Keychain

// ✅ CORRECT - iOS keychain storage
import Security

func saveToKeychain(key: String, value: String) {
    let data = value.data(using: .utf8)!
    let query: [String: Any] = [
        kSecClass as String: kSecClassGenericPassword,
        kSecAttrAccount as String: key,
        kSecValueData as String: data,
        kSecAttrAccessible as String: kSecAttrAccessibleWhenUnlockedThisDeviceOnly
    ]

    SecItemDelete(query as CFDictionary)
    SecItemAdd(query as CFDictionary, nil)
}

#### 🔍 Why It Matters:

What to Encrypt:

• Authentication tokens
• Passwords
• Credit card information
• Personal Identifiable Information (PII)
• Health data
• Any data you wouldn't want displayed on a billboard

• Public app settings
• UI preferences (theme, language)
• Non-sensitive cache data

• react-native-encrypted-storage: Encrypted AsyncStorage alternative
• react-native-keychain: Access device keychain/keystore
• Jetpack Security (Android): EncryptedSharedPreferences
• iOS Keychain Services: Built-in secure storage

Mistake #3: Trusting HTTP (No HTTPS)

The Problem: Sending data over unencrypted HTTP connections.

Think of it like this: HTTP is like shouting your password across a crowded room. HTTPS is like whispering it directly into someone's ear. Always whisper (use HTTPS).

#### ❌ What NOT to Do

Example 1: Using HTTP Instead of HTTPS

// ❌ WRONG - Unencrypted connection!
fetch('http://api.example.com/login', {
  method: 'POST',
  body: JSON.stringify({ password: 'myPassword123' })
});

Why this is bad: Anyone on the same WiFi can see your password in plain text.

---

Example 2: Disabling SSL Verification

React Native:

// ❌ WRONG - Accepts invalid certificates!
fetch('https://api.example.com', {
  agent: new https.Agent({
    rejectUnauthorized: false  // DON'T DO THIS!
  })
});

Android:

// ❌ WRONG - Accepts ANY certificate!
TrustManager[] trustAllCerts = new TrustManager[]{
    new X509TrustManager() {
        public void checkClientTrusted(X509Certificate[] chain, String authType) {}
        public void checkServerTrusted(X509Certificate[] chain, String authType) {}
        public X509Certificate[] getAcceptedIssuers() { return new X509Certificate[]{}; }
    }
};

Why this is bad: This defeats the entire purpose of HTTPS. Attackers can intercept and modify your data.

#### ✅ What to Do Instead

Solution 1: Always Use HTTPS

// ✅ CORRECT - Always use HTTPS
fetch('https://api.example.com/data');

---

Solution 2: Implement Certificate Pinning (Advanced)

React Native:

// ✅ CORRECT - Pin certificates for extra security
import { fetch } from 'react-native-ssl-pinning';

fetch('https://api.example.com/data', {
  method: 'GET',
  sslPinning: {
    certs: ['mycert']  // Certificate in your bundle
  }
});

Android - Network Security Configuration:

Create res/xml/network_security_config.xml:

    
        api.example.com
        
            7HIpactkIAq2Y49orFOOQKurWxmmSFZhBCoQYcRhJ3Y=
            YLh1dUR9y6Kja30RrAn7JKnbQG/uEtLMkBgFF2Fuihg=
        
    

iOS - App Transport Security:

Add to Info.plist:

NSAppTransportSecurity

    NSAllowsArbitraryLoads
    

---

Solution 3: Use Modern TLS (1.2 or 1.3)

Configure your backend to only accept modern TLS versions with strong cipher suites. This is done on the server side, not in your app.

#### 🔍 Why It Matters:

Man-in-the-Middle (MITM) Attacks: When you use HTTP or accept invalid HTTPS certificates, attackers on the same WiFi network can:

• Read all your traffic
• Steal passwords and tokens
• Modify API responses
• Inject malicious code

#### 🛠️ Tools to Help:

• react-native-ssl-pinning: Certificate pinning for RN
• Charles Proxy: Test your app's network security
• Wireshark: Network packet analyzer
• SSL Labs: Test your server's SSL configuration

Mistake #4: Weak Authentication

The Problem: Poor authentication implementation that's easy to bypass or exploit.

#### ❌ What NOT to Do

Example 1: Client-Side Authentication

// ❌ WRONG - Never trust the client
function isAuthenticated() {
  return localStorage.getItem('isLoggedIn') === 'true';
}

Why this is bad: Anyone can open the browser console and set localStorage.setItem('isLoggedIn', 'true') to bypass authentication.

---

Example 2: Weak Password Policies

// ❌ WRONG - Too weak
if (password.length >= 6) {
  // Accept password - "123456" would be valid!
}

Why this is bad: "123456" is still the most common password. Short passwords are easily cracked.

---

Example 3: Tokens That Never Expire

// ❌ WRONG - Token lasts forever
const token = jwt.sign({ userId }, SECRET_KEY);

Why this is bad: If the token is stolen, the attacker has permanent access to the account.

---

Example 4: Passwords in URLs

// ❌ TERRIBLE - Passwords logged everywhere
fetch('/api/login?username=john&password=secret123');

Why this is bad: URLs are logged in server logs, browser history, proxy logs, and analytics. The password is now exposed everywhere.

---

#### ✅ What to Do Instead

Solution 1: Proper JWT Authentication Flow (React Native)

Step 1: Login and store tokens securely

// ✅ CORRECT - Secure login flow
const login = async (email, password) => {
  const response = await fetch('https://api.example.com/auth/login', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email, password })
  });

  const { accessToken, refreshToken } = await response.json();

  // Store in encrypted storage, NOT localStorage
  await EncryptedStorage.setItem('access_token', accessToken);
  await EncryptedStorage.setItem('refresh_token', refreshToken);
};

Step 2: Use token for authenticated requests

// ✅ CORRECT - Include token in headers
const fetchUserData = async () => {
  const token = await EncryptedStorage.getItem('access_token');

  const response = await fetch('https://api.example.com/user', {
    headers: {
      'Authorization': 'Bearer ' + token
    }
  });

  return response.json();
};

---

Solution 2: Token Refresh Implementation

// ✅ CORRECT - Refresh expired access tokens
const refreshAccessToken = async () => {
  const refreshToken = await EncryptedStorage.getItem('refresh_token');

  const response = await fetch('https://api.example.com/auth/refresh', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ refreshToken })
  });

  const { accessToken } = await response.json();
  await EncryptedStorage.setItem('access_token', accessToken);

  return accessToken;
};

---

Solution 3: Biometrics as Second Factor (Not Primary)

// ✅ CORRECT - Biometrics + backend verification
import ReactNativeBiometrics from 'react-native-biometrics';

const authenticateWithBiometrics = async () => {
  const { success } = await ReactNativeBiometrics.simplePrompt({
    promptMessage: 'Confirm fingerprint'
  });

  if (success) {
    // Still verify with backend - don't trust biometrics alone!
    const token = await EncryptedStorage.getItem('access_token');
    return verifyTokenWithBackend(token);
  }
};

---

Solution 4: Strong Password Requirements

// ✅ CORRECT - Enforce strong passwords
function validatePassword(password) {
  // Minimum 12 characters
  if (password.length < 12) return false;

  // Must contain uppercase, lowercase, number, special char
  const hasUpperCase = /[A-Z]/.test(password);
  const hasLowerCase = /[a-z]/.test(password);
  const hasNumbers = /d/.test(password);
  const hasSpecialChar = /[!@#$%^&*]/.test(password);

  return hasUpperCase && hasLowerCase && hasNumbers && hasSpecialChar;
}

---

Solution 5: Account Lockout After Failed Attempts

// ✅ CORRECT - Prevent brute force attacks
// Backend: Track failed login attempts
let failedAttempts = 0;
const MAX_ATTEMPTS = 5;

app.post('/login', async (req, res) => {
  if (failedAttempts >= MAX_ATTEMPTS) {
    return res.status(429).json({
      error: 'Account locked. Try again in 15 minutes.'
    });
  }

  const user = await authenticateUser(req.body);

  if (!user) {
    failedAttempts++;
    return res.status(401).json({ error: 'Invalid credentials' });
  }

  failedAttempts = 0;
  // Generate tokens...
});

#### 🔍 Why It Matters:

89% of security breaches involve stolen credentials. Weak authentication is the easiest way for attackers to gain access to your app and user data.

2025 Authentication Threats:

• AI-Powered Attacks: 703% increase in credential phishing using AI
• Ransomware-as-a-Service (RaaS): Professional attack kits for hire
• Credential Stuffing: Automated testing of stolen passwords
• SMS Interception: Why banks are banning SMS OTP

• Short expiration for access tokens (15-30 minutes)
• Longer expiration for refresh tokens (7-30 days)
• Store refresh token securely
• Implement token rotation
• Include minimal information in JWT payload

• OAuth 2.0 / OpenID Connect: Industry standard
• Firebase Authentication: Easy to implement
• Auth0: Managed authentication service
• AWS Cognito: Scalable user authentication
• Supabase Auth: Open-source alternative

Why this matters: Banks in Hong Kong and Malaysia are banning SMS OTP for online transactions due to security concerns. Passwords are becoming obsolete.

Modern alternatives you should implement:

// ✅ CORRECT - Device-based authentication
import ReactNativeBiometrics from 'react-native-biometrics';

const authenticateWithBiometrics = async () => {
  const { success, signature } = await ReactNativeBiometrics.createSignature({
    promptMessage: 'Authenticate to continue',
    payload: 'unique-challenge-string'
  });

  if (success) {
    // Send signature to backend for verification
    await verifyBiometricSignature(signature);
  }
};

Passwordless options for 2025:

• Biometric Authentication: Face ID, Touch ID, fingerprint
• Hardware Security Keys: FIDO2/WebAuthn (YubiKey, etc.)
• Magic Links: Email-based one-time login links
• Passkeys: Apple/Google's password replacement (most secure)

• No passwords to steal or phish
• Can't be reused across sites
• Resistant to credential stuffing attacks
• Better user experience (no password to remember)

Mistake #5: No Input Validation

The Problem: Trusting user input without validation or sanitization.

Think of it like this: Not checking user input is like letting anyone write anything in your guestbook. They could write nice messages, or they could write instructions that break your entire system.

#### ❌ What NOT to Do

Example 1: SQL Injection Vulnerability

// ❌ WRONG - SQL Injection attack possible!
const userId = req.query.id;
db.query('SELECT * FROM users WHERE id = ' + userId);

Why this is bad: A hacker could send "?id=1 OR 1=1" and get access to ALL users in the database, not just user #1.

---

Example 2: No Email Validation

// ❌ WRONG - No validation at all
const email = req.body.email;
await sendEmail(email, 'Welcome!');

Why this is bad: Anyone could enter "not-an-email" or malicious code. Your email system will crash or send spam.

---

Example 3: Trusting Client-Side Validation Only

// ❌ WRONG - Frontend validation is easy to bypass
if (email.includes('@')) {
  submitForm(email); // No backend check!
}

Why this is bad: Anyone can open the browser console and bypass your JavaScript validation. Client-side validation is just for UX, not security.

---

#### ✅ What to Do Instead

Solution 1: Always Validate on Backend

// ✅ CORRECT - Validate every input field
import validator from 'validator';

app.post('/register', async (req, res) => {
  const { email, age, website } = req.body;

  // Validate email format
  if (!validator.isEmail(email)) {
    return res.status(400).json({ error: 'Invalid email' });
  }

  // Validate age is a number between 18-120
  if (!validator.isInt(age, { min: 18, max: 120 })) {
    return res.status(400).json({ error: 'Invalid age' });
  }

  // Validate website URL format
  if (website && !validator.isURL(website)) {
    return res.status(400).json({ error: 'Invalid URL' });
  }

  // Sanitize email (remove dots, lowercase, etc.)
  const cleanEmail = validator.normalizeEmail(email);

  // Now safe to continue with registration...
});

---

Solution 2: Use Parameterized Queries (Prevent SQL Injection)

// ✅ CORRECT - Using parameterized queries
const userId = req.query.id;
const user = await db.query(
  'SELECT * FROM users WHERE id = ?',
  [userId]
);

// Or even better: Use an ORM like Sequelize
const user = await User.findByPk(userId);

---

Solution 3: Sanitize HTML/JS Input

// ✅ CORRECT - Remove dangerous HTML/JS
import DOMPurify from 'isomorphic-dompurify';

const userComment = req.body.comment;
const sanitized = DOMPurify.sanitize(userComment);
// Now safe to display - script tags and dangerous HTML removed

---

Solution 4: Implement Rate Limiting

// ✅ CORRECT - Prevent spam and brute force attacks
import rateLimit from 'express-rate-limit';

const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100, // Limit each IP to 100 requests per 15 minutes
  message: 'Too many requests, please try again later'
});

app.use('/api/', limiter);

#### 🔍 Why It Matters:

Common Injection Attacks:

• SQL Injection: Manipulate database queries
• NoSQL Injection: MongoDB and other NoSQL databases
• Command Injection: Execute system commands
• XSS (Cross-Site Scripting): Inject malicious scripts
• Path Traversal: Access files outside intended directory

• validator.js: String validation and sanitization
• joi: Schema validation for Node.js
• yup: JavaScript schema validation
• DOMPurify: Sanitize HTML
• express-rate-limit: Rate limiting middleware

Mistake #6: Exposing Debug Code in Production

The Problem: Leaving debug endpoints, console logs, and development code in production builds.

#### ❌ What NOT to Do

Example 1: Console Logs with Sensitive Data

// ❌ TERRIBLE - Remove before production!
console.log('User password:', password);
console.log('API Key:', apiKey);
console.log('Auth token:', token);

Why this is bad: These logs are visible in crash reports, monitoring tools, and device logs. Sensitive data is exposed to anyone with access to logs.

---

Example 2: Debug Endpoints in Production

// ❌ WRONG - Debug endpoint accessible to everyone
app.get('/debug/users', (req, res) => {
  res.json(await User.findAll());
});

Why this is bad: Anyone who finds this URL (by guessing or scanning) can download your entire user database without authentication.

---

Example 3: Exposing Error Stack Traces

// ❌ WRONG - Reveals your code structure
app.use((err, req, res, next) => {
  res.status(500).json({
    error: err.message,
    stack: err.stack  // Shows file paths, function names, etc.
  });
});

Why this is bad: Stack traces show your file structure, function names, libraries, and database queries. Hackers use this to find vulnerabilities.

---

#### ✅ What to Do Instead

Solution 1: Auto-Remove Console Logs in Production Builds

// ✅ CORRECT - babel.config.js for React Native
module.exports = {
  presets: ['module:metro-react-native-babel-preset'],
  env: {
    production: {
      plugins: ['transform-remove-console']
    }
  }
};

---

Solution 2: Use Proper Logging Library

// ✅ CORRECT - Professional logging
import logger from 'winston';

// Development: Use console.log
if (process.env.NODE_ENV === 'development') {
  console.log('Debug info:', data);
}

// Production: Use structured logging
logger.info('User logged in', { userId });
logger.error('Login failed', { email, reason });

---

Solution 3: Environment-Based Configuration

// ✅ CORRECT - Only debug in development
if (__DEV__) {
  // React Native - only runs in development
  console.log('Development mode');
}

if (process.env.NODE_ENV === 'production') {
  // Disable all debug features in production
  console.log = () => {};
  console.debug = () => {};
}

---

Solution 4: Generic Error Messages for Users

// ✅ CORRECT - Hide details from users, log internally
app.use((err, req, res, next) => {
  // Log detailed error internally for developers
  logger.error('Error occurred', {
    error: err.message,
    stack: err.stack,
    url: req.url
  });

  // Send generic message to client (no sensitive info)
  res.status(500).json({
    error: 'An internal error occurred'
  });
});

#### 🔍 Why It Matters:

What Attackers Learn from Debug Info:

• Your database structure
• API endpoints
• Authentication logic
• Error patterns
• Code structure
• Third-party services you use

• babel-plugin-transform-remove-console: Remove console logs
• winston: Professional logging library
• Sentry: Error tracking and monitoring
• ProGuard/R8 (Android): Remove debug code

Mistake #7: No Code Protection

The Problem: Shipping apps without any obfuscation or protection from reverse engineering.

Think of it like this: Sending unprotected code is like selling a product with the recipe printed on the box. Competitors can copy your secret formula and steal your business.

#### ❌ What NOT to Do

Example 1: Hardcoded License Keys in Readable Code

// ❌ WRONG - Anyone can decompile and see this
function validateLicense(key) {
  return key === 'SUPER-SECRET-KEY-12345';
}

Why this is bad: Your JavaScript code is readable in the app bundle. Anyone can extract the license key in 5 minutes.

---

Example 2: Client-Side Business Logic

// ❌ WRONG - Easily modified by hackers
const isPremiumUser = (userId) => {
  // Premium users: ID > 1000
  return userId > 1000;
};

Why this is bad: Hackers can modify this code to always return "true" and get premium features for free.

---

#### ✅ What to Do Instead

Solution 1: Enable Hermes Engine (React Native)

// ✅ CORRECT - android/app/build.gradle
project.ext.react = [
    enableHermes: true  // Compiles to bytecode instead of JavaScript
]

---

Solution 2: Enable ProGuard/R8 Obfuscation (Android)

// ✅ CORRECT - android/app/build.gradle
buildTypes {
    release {
        minifyEnabled true
        shrinkResources true
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt')
    }
}

---

Solution 3: Strip Debug Symbols (iOS)

// ✅ CORRECT - Xcode Build Settings
STRIP_INSTALLED_PRODUCT = YES
STRIP_STYLE = non-global
DEPLOYMENT_POSTPROCESSING = YES

---

Solution 4: Root/Jailbreak Detection

// ✅ CORRECT - Detect compromised devices
import JailMonkey from 'jail-monkey';

useEffect(() => {
  if (JailMonkey.isJailBroken()) {
    Alert.alert(
      'Security Warning',
      'This app cannot run on jailbroken devices',
      [{ text: 'Exit', onPress: () => BackHandler.exitApp() }]
    );
  }
}, []);

---

Solution 5: Move Sensitive Logic to Backend

// ❌ DON'T: Check premium status on client (can be hacked)
const isPremium = checkPremiumLocal(userId);

// ✅ DO: Always validate on backend
const checkPremiumStatus = async (userId) => {
  const response = await fetch('/api/user/' + userId + '/premium');
  return response.json();
};

#### 🔍 Why It Matters:

What Attackers Can Do:

• Extract API keys
• Understand business logic
• Clone your app
• Remove licensing checks
• Bypass premium features
• Find vulnerabilities

1. Code Obfuscation: Make code hard to read
2. Root/Jailbreak Detection: Detect compromised devices
3. Runtime Integrity Checks: Detect tampering
4. Server-Side Validation: Never trust the client
5. Certificate Pinning: Prevent traffic interception

• Hermes (React Native): Bytecode compilation
• ProGuard/R8 (Android): Code shrinking and obfuscation
• DexGuard: Commercial-grade Android protection
• iXGuard (iOS): iOS obfuscation
• jail-monkey: Root/jailbreak detection
• react-native-device-info: Device security checks

Platform-Specific Quick Wins

React Native Security Checklist ✅

5-Minute Improvements:

1. Add .env to .gitignore

.gitignore

1. Use Encrypted Storage

1. Enable Hermes

1. Add Certificate Pinning

1. Implement Jailbreak Detection

Android Security Essentials 🤖

1. Use EncryptedSharedPreferences

1. Enable R8/ProGuard

1. Network Security Config

1. Use Android Keystore

1. Play Integrity API

iOS Security Must-Haves 🍎

1. Use Keychain Services

1. Enable App Transport Security

1. Strip Debug Symbols

1. Implement DeviceCheck

1. Use Face ID/Touch ID

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The Security Toolbox 🧰

Free Tools Every Developer Should Use:

1. MobSF (Mobile Security Framework)

• Automated security testing
• Static + Dynamic analysis
• Works offline
• Free and open-source

• Dependency vulnerability scanning
• Integrates with GitHub
• Free for open-source projects

• Web application security scanner
• Find API vulnerabilities
• Completely free

• Fast vulnerability scanner
• Template-based testing
• Community-driven

• Static analysis for security
• Custom rule creation
• IDE integration

Automated Security in CI/CD:

GitHub Actions Example:

name: Security Scan on: [push]

jobs: security:

runs-on: ubuntu-latest
steps:
  - uses: actions/checkout@v2

  - name: Run Snyk
    run: npx snyk test

  - name: Run npm audit
    run: npm audit

  - name: Scan for secrets
    uses: trufflesecurity/trufflehog@main

GitLab CI Example:

security_scan: script:

- npm audit
- npx snyk test
- npx retire --exitwith 1

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Testing Your App's Security 🔍

DIY Security Audit Checklist:

Step 1: Decompile Your Own App

• Use apktool (Android) or class-dump (iOS)
• Search for hardcoded secrets
• Check if code is obfuscated

• Use Charles Proxy or Burp Suite
• Check if HTTPS is enforced
• Verify certificate pinning works
• Look for sensitive data in transit

• Try using expired tokens
• Test password reset flow
• Check session timeout
• Verify logout clears tokens

• Send malformed JSON
• Try SQL injection patterns
• Test XSS payloads
• Send extremely large inputs

• On Android: adb shell, find app data
• On iOS: Use Xcode to inspect app container
• Verify sensitive data is encrypted

When to Hire Security Experts:

You Should Hire Pros If:

• You handle payment information
• You store health data (HIPAA compliance)
• You have 100K+ users
• You've had a security incident
• You're in a regulated industry
• You're raising funding (due diligence)

• Source code review
• Network traffic analysis
• Authentication bypass attempts
• Privilege escalation tests
• Data leakage analysis
• Compliance verification

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Pre-Launch Security Checklist ✓

Must-Fix Before Launch:

• [ ] No hardcoded API keys or secrets
• [ ] All sensitive data encrypted at rest
• [ ] HTTPS enforced for all connections
• [ ] Certificate pinning implemented
• [ ] Authentication tokens expire and refresh
• [ ] Input validation on all endpoints
• [ ] Rate limiting implemented
• [ ] No console.log in production
• [ ] Debug endpoints removed
• [ ] Code obfuscation enabled
• [ ] Root/jailbreak detection active
• [ ] Third-party dependencies audited
• [ ] Privacy policy updated
• [ ] Terms of service include security clause
• [ ] Incident response plan exists

Nice-to-Have Improvements:

• [ ] Biometric authentication
• [ ] Multi-factor authentication (MFA)
• [ ] Advanced obfuscation (DexGuard, iXGuard)
• [ ] Runtime application self-protection (RASP)
• [ ] Bug bounty program
• [ ] Security monitoring (Sentry, Datadog)
• [ ] Penetration testing completed
• [ ] SOC 2 compliance (for enterprise)

Key Takeaways 🎯

The 7 Deadly Security Sins:

1. ❌ Hardcoded secrets
2. ❌ Unencrypted storage
3. ❌ HTTP connections
4. ❌ Weak authentication
5. ❌ No input validation
6. ❌ Debug code in production
7. ❌ No code protection

• Security is not optional - It's a core feature
• Start early - Security debt is expensive to fix later
• Defense in depth - Multiple layers of protection
• Never trust the client - Validate everything on the backend
• Stay updated - New vulnerabilities discovered daily

1. Check your code for hardcoded API keys (search for "apiKey", "api_key", "secret")
2. Run npm audit to check for vulnerable dependencies
3. Add encrypted storage for sensitive data
4. Enforce HTTPS in your app
5. Remove all console.log statements from production builds

• OWASP Mobile Security Project
• NIST Mobile Security Guidelines
• Google's Android Security Best Practices
• Apple's iOS Security Guide

Frequently Asked Questions (FAQ)

Q: How do I know if my app has security vulnerabilities?

Q: Is HTTPS really necessary for a small app?

Q: What's the fastest way to improve my app's security?

1. Search for hardcoded API keys and move them to environment variables
2. Replace AsyncStorage with EncryptedStorage for sensitive data
3. Enforce HTTPS by blocking HTTP in your network security config

Q: Should I hire a security expert?

Q: How often should I update my app's security?

• Weekly: npm audit for dependency vulnerabilities
• Monthly: Review new OWASP mobile security advisories
• Before each release: Full security checklist (see above)
• Annually: Professional security audit if you have sensitive data

Q: Can encrypted storage be hacked?

• Device is rooted/jailbroken (use root detection)
• User has weak device PIN (educate users)
• Your encryption key is hardcoded (use platform keychains instead)

Q: Is React Native as secure as native apps?

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The Bottom Line

98% of mobile apps have security vulnerabilities. Don't be part of that statistic.

Security doesn't have to be complicated or expensive. Start with these basics:

• Don't hardcode secrets
• Encrypt sensitive data
• Use HTTPS everywhere
• Validate all inputs
• Remove debug code
• Test your app's security

Your users trust you with their data. Don't let them down.

What's your biggest security concern? Check your app against this checklist and fix at least one vulnerability today. Future you (and your users) will thank you.

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P.S. Want a downloadable security checklist you can use for every app release? The pre-launch checklist above is your starting point. Print it, share it with your team, and make security a habit, not an afterthought.

Remember: The best time to implement security was during initial development. The second-best time is now.

Stop vibe coding. Start securing. 🔒