Swift Application Security: Top 10 Vulnerabilities for iOS/macOS

Introduction: Why Swift Application Security Is Critical

Swift is a powerful and modern programming language created by Apple for developing applications for iOS, macOS, watchOS, and tvOS. Despite built-in security mechanisms (ARC, safe memory management, optional types), thousands of applications fall victim to attacks every year due to developer errors. According to the OWASP Mobile Top 10 report, most vulnerabilities in mobile applications occur on the client side. In this article, we will break down the 10 most common vulnerabilities in Swift applications, provide code examples, and show how to avoid them.

1. Insecure Data Storage

Problem

Developers often save confidential data (tokens, passwords, API keys) in UserDefaults, Plist files, or Core Data without encryption. On jailbroken devices, an attacker can easily access them.

Example of Vulnerable Code

// Vulnerable codeUserDefaults.standard.set("secret_token_123", forKey: "api_token")UserDefaults.standard.set("password123", forKey: "user_password")

Solution

Use Keychain to store sensitive data. Swift has convenient wrappers such as KeychainSwift or the Security framework.

// Secure storage with Keychainimport KeychainSwift

let keychain = KeychainSwift()keychain.set("secret_token_123", forKey: "api_token")keychain.set("password123", forKey: "user_password", withAccess: .accessibleWhenUnlockedThisDeviceOnly)

2. Code Injection & SQL Injection

Problem

If your application uses SQLite, Core Data with NSPredicate, or WebView to display web content, an attacker can inject malicious code through user input.

Example of Vulnerable Code

// Vulnerable SQLite querylet userInput = "1' OR '1'='1"let query = "SELECT * FROM users WHERE id = '\\(userInput)'"

Solution

Use parameterized queries or NSPredicate with safe substitutions.

// Secure query with parameterslet query = "SELECT * FROM users WHERE id = ?"let statement = try db.prepare(query)try statement.bind(1, userInput)

3. Insecure Network Communication

Problem

Using HTTP instead of HTTPS, ignoring SSL certificates (App Transport Security), or sending data without encryption.

Example of Vulnerable Code

// Vulnerable code: disabling ATSlet url = URL(string: "http://example.com/api/login")!let task = URLSession.shared.dataTask(with: url) { data, response, error in    // Processing unsecured data}

Solution

Configure App Transport Security (ATS) in Info.plist and use HTTPS. For certificate verification, apply SSL pinning.

// Secure request with SSL Pinning (example with Alamofire)let evaluator = PinnedCertificatesTrustEvaluator(certificates: [certificate])let session = Session(serverTrustManager: ServerTrustManager(evaluators: ["example.com": evaluator]))session.request("https://example.com/api/login").responseJSON { response in    // Processing secured data}

4. WebView Injection

Problem

Loading HTML content with user data into WKWebView without sanitization can lead to XSS attacks and cookie theft.

Example of Vulnerable Code

// Vulnerable codelet userComment = "<script>alert('XSS')</script>"let html