- Description: Attackers on a compromised device intercept or alter messages exchanged between the native application and the webview via the bridge.
- How webviewjavascriptbridge Contributes: The bridge is the communication channel, making this attack possible. It's distinct from webview HTTPS security.
- Example: An attacker intercepts a message containing a user's session token sent from the native app to the webview, allowing them to impersonate the user.
- Impact: Complete compromise of user accounts, data theft, unauthorized actions.
- Risk Severity: Critical
- Mitigation Strategies:
- Cryptographic Message Integrity: Implement message signing (e.g., SHA-256 with a securely stored key). Verify signatures on both sides before processing.
- Encryption of Bridge Messages: Encrypt the entire message payload (e.g., AES with a securely managed key).
- Root/Jailbreak Detection: Detect compromised devices and limit/disable functionality.
- Code Obfuscation & Anti-Tampering: Hinder reverse engineering of the bridge communication.
Attack Surface: 2. Unauthorized Native Function Calls
- Description: Attackers inject malicious JavaScript that calls native functions exposed by the bridge with unexpected or malicious parameters.
- How webviewjavascriptbridge Contributes: The bridge's core purpose is to expose native functions to JavaScript, creating this direct attack vector.
- Example: An attacker injects JavaScript that calls a native function designed to delete user data, passing a wildcard to delete all data.
- Impact: Data loss, denial of service, privilege escalation, execution of arbitrary native code.
- Risk Severity: Critical
- Mitigation Strategies:
- Strict Input Validation: Thoroughly validate all input from JavaScript in every exposed native function. Use whitelisting.
- Principle of Least Privilege: Expose only the absolute minimum necessary native functions.
- Contextual Authorization: Verify the calling context (e.g., origin URL) before execution.
- Rate Limiting: Limit the frequency of native function calls.
Attack Surface: 3. JavaScript Hijacking of Bridge Callbacks
- Description: Attackers inject JavaScript that overwrites or intercepts callbacks used by the bridge, stealing data or manipulating behavior.
- How webviewjavascriptbridge Contributes: The bridge relies on JavaScript callbacks for asynchronous communication, making them a direct target.
- Example: An attacker overwrites a callback receiving sensitive user data, redirecting it to their server.
- Impact: Data theft, manipulation of application logic, potential for further attacks.
- Risk Severity: High
- Mitigation Strategies:
- Callback Isolation: Use IIFEs or closures to isolate callback handling, preventing interference.
- Minimize Callback Data: Return only essential data in callbacks.
- Data Sanitization (on Native Side): Sanitize data before passing it to the JavaScript callback.
Attack Surface: 4. Reflection-Based Attacks
- Description: Attackers exploit vulnerabilities in how the bridge handles message routing and function dispatch, potentially calling unintended native functions.
- How webviewjavascriptbridge Contributes: The bridge's internal implementation of message handling and function dispatch can introduce these vulnerabilities if not designed securely.
- Example: An attacker crafts a message with a manipulated function name that, due to a flaw in the bridge's logic, calls a privileged function not intended for exposure.
- Impact: Execution of arbitrary native code, privilege escalation, data breaches.
- Risk Severity: High
- Mitigation Strategies:
- Avoid String-Based Dispatch: Use secure dispatch (function pointers, static interfaces) instead of string-based names.
- Strict Type Checking: Enforce rigorous type checking on all parameters and function identifiers.
- Code Review: Thoroughly review the bridge implementation for reflection vulnerabilities.