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Threat Model Analysis for johnlui/swift-on-ios

Threat: Unauthorized Native Function Execution via Bridge

  • Description: An attacker injects malicious JavaScript into the webview (e.g., through a compromised third-party library, XSS on a whitelisted domain, or a compromised web server). This JavaScript attempts to call native functions exposed by the swift-on-ios bridge that it shouldn't have access to. The attacker crafts specific JavaScript calls designed to trigger unintended actions on the device.
    • Impact:
      • Data exfiltration (reading files, contacts, location data).
      • Device compromise (installing malware, modifying system settings).
      • Privacy violation (activating camera/microphone without user consent).
      • Financial loss (if the app handles payments or sensitive financial data).
    • Affected Component: The JavaScript-to-native bridge mechanism (specifically, the functions exposed by gonative-ios and wrapped by swift-on-ios). This includes any custom native functions added by the developers.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Strict Input Validation: Implement rigorous validation of all data passed from JavaScript to native functions. Use a whitelist approach, defining allowed data types, formats, and ranges. Reject any input that doesn't conform.
      • Principle of Least Privilege: Expose only the absolute minimum necessary native functions. Avoid exposing generic file system access, shell command execution, or other powerful capabilities.
      • Secure Coding Practices: Follow secure coding guidelines for both Swift and JavaScript to prevent common vulnerabilities like buffer overflows or format string bugs in the bridge code.
      • Code Reviews: Conduct thorough code reviews of the bridge implementation, focusing on data handling and access control.
      • Context Isolation: Ensure the webview operates within a properly sandboxed environment, limiting its access to the rest of the system.

Threat: Malicious JavaScript Injection via Native Code

  • Description: A vulnerability in the native Swift code (or the underlying gonative-ios library) allows an attacker to inject malicious JavaScript into the webview. This could occur if the native code incorrectly handles data received from a native API or user input and passes it directly to webView.evaluateJavaScript() without proper sanitization.
    • Impact:
      • Complete control over the webview's content and behavior.
      • Theft of cookies, local storage data, and other sensitive information stored within the webview.
      • Execution of arbitrary JavaScript code with the privileges of the webview.
      • Bypass of security controls implemented within the web application.
    • Affected Component: The native code that interacts with the webview, specifically any code that calls webView.evaluateJavaScript() or similar methods. This includes the swift-on-ios wrapper and any custom native code.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Output Encoding: Always properly encode and escape any data passed from native code to JavaScript. Use appropriate escaping mechanisms (e.g., JavaScript string escaping) to prevent script injection.
      • Content Security Policy (CSP): Implement a strict CSP within the web content to limit the sources of executable scripts and other resources. This can mitigate the impact of injected JavaScript, even if injection occurs.
      • Code Reviews: Thoroughly review all native code that interacts with the webview, paying close attention to data handling and webView.evaluateJavaScript() calls.
      • Input Validation (Indirect): Even though the primary input is from native sources, validate any data that originates from potentially untrusted sources (e.g., network responses, user input) before passing it to the webview.

Threat: Configuration File Tampering

  • Description: An attacker with access to the device (e.g., through a jailbreak or a malicious app) modifies the swift-on-ios configuration files (e.g., GoNativeIOS-Config.json). They could change the allowed URL whitelist, disable security features, or alter other settings to their advantage.
    • Impact:
      • Loading of malicious web content from attacker-controlled domains.
      • Bypass of security restrictions imposed by the configuration.
      • Exposure of sensitive data or device features.
    • Affected Component: The configuration files used by swift-on-ios (and gonative-ios), typically stored within the application's bundle or data container.
    • Risk Severity: High
    • Mitigation Strategies:
      • Secure Storage: Store configuration files in a secure location on the device, using appropriate file permissions to restrict access. Consider using the iOS Keychain for sensitive configuration values.
      • Integrity Checks: Implement integrity checks (e.g., checksums, digital signatures, or hash comparisons) to verify that the configuration files have not been tampered with. The application should refuse to load if the integrity check fails.
      • Code Signing: Ensure the application is properly code-signed. While this doesn't directly protect configuration files, it helps prevent attackers from modifying the application binary to bypass integrity checks.
      • Obfuscation (Limited Effectiveness): Obfuscating the configuration file format or location can make it slightly harder for an attacker to find and modify it, but this is not a strong security measure.