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input_method_manager_wrapper.md

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InputMethodManagerWrapper Security

Component Focus: Chromium's InputMethodManagerWrapper on Android in content/public/android/java/src/org/chromium/content_public/browser/InputMethodManagerWrapper.java. This interface interacts with the IMF.

Potential Logic Flaws:

  • Input Injection: Vulnerabilities could allow injecting arbitrary text or manipulating input focus. The showSoftInput and hideSoftInput functions, which control the soft keyboard, are critical. If these functions are called at the wrong time or with incorrect parameters, a malicious website could potentially inject text or control input focus. The restartInput function, which restarts the input method, could also be a potential attack vector if not handled securely.
  • Data Leakage: Sensitive data, such as user input or IMF state, could be leaked. The updateSelection, updateCursorAnchorInfo, and updateExtractedText functions, which handle text selection and composition, should be reviewed. Improper handling of these updates could expose user input or internal browser state.
  • Race Conditions: Race conditions could occur during IMF interaction, especially with asynchronous operations. The onWindowFocusChanged and onViewFocusChanged functions, which handle focus changes, and the interaction with the Delegate for multi-display support, are potential sources of race conditions if not properly synchronized.
  • Denial of Service (DoS): Excessive requests or exploits disrupting IMF functionality could cause DoS. All wrapper functions should be reviewed for rate limiting and input validation to mitigate DoS risks. The onInputConnectionCreated function, which signals the creation of an input connection, should be reviewed for proper handling of potentially malicious input.

Further Analysis and Potential Issues:

The InputMethodManagerWrapper.java file ($5,000 VRP payout) defines the InputMethodManagerWrapper interface. Key functions and security considerations include:

  • showSoftInput(), hideSoftInput(): These functions control the soft keyboard visibility. They should be reviewed for proper handling of view references, input flags, and result receivers. Calling these functions at the wrong time or with incorrect parameters could lead to input injection or UI spoofing vulnerabilities. The interaction with the underlying InputMethodManager should be carefully analyzed.

  • restartInput(): This function restarts the input method. It should be reviewed for proper handling of view references and potential race conditions. A malicious website could potentially use this function to disrupt input or gain unauthorized access to input state.

  • isActive(), isAcceptingText(): These functions check the input method's state. They should be reviewed for accurate and consistent reporting of input state to prevent inconsistencies or unexpected behavior.

  • updateSelection(), updateCursorAnchorInfo(), updateExtractedText(): These functions handle text selection, cursor position, and extracted text updates. They should be reviewed for proper data handling, input validation, and prevention of data leakage. The interaction with the underlying input method and the handling of sensitive data, such as user input and selection ranges, are crucial for security.

  • onWindowFocusChanged(), onViewFocusChanged(): These functions handle window and view focus changes. They should be reviewed for proper handling of focus events, synchronization with other components, and prevention of race conditions. The interaction with the input method and the handling of focus transitions are important for security.

  • onKeyboardBoundsUnchanged(): This function is called when the keyboard bounds haven't changed. It should be reviewed for proper handling of this event and any potential impact on input or UI state.

  • Delegate Interface (hasInputConnection()): The Delegate interface provides a way for embedders to customize the input connection handling, potentially for multi-display support. The hasInputConnection() function should be reviewed for proper interaction with the input method and prevention of unauthorized access or data leakage.

  • onInputConnectionCreated(): This function is called when a non-null input connection is created. It should be reviewed for proper handling of this event and any potential security implications, such as input injection or denial-of-service attacks.

Areas Requiring Further Investigation:

  • Analyze input method interaction functions (showSoftInput, hideSoftInput, restartInput) for input injection, data leakage, and race conditions.
  • Review event handling and callbacks, especially related to focus changes and input method state updates.
  • Investigate data handling and communication with the IMF, particularly in the updateSelection, updateCursorAnchorInfo, and updateExtractedText functions.
  • Analyze the interaction with other Chromium components, such as the render widget host view and the text input manager.
  • Review resource management for potential DoS vulnerabilities.
  • Test the wrapper with various input methods and scenarios.
  • Analyze the Delegate interface and its interaction with the input method for multi-display support.
  • Review the onInputConnectionCreated function for secure handling of input connection creation.

Secure Contexts and InputMethodManagerWrapper:

The input method manager wrapper should operate securely regardless of context.

Privacy Implications:

The wrapper handles user input and IMF state. The implementation should protect sensitive data and prevent leaks.

Additional Notes:

Files reviewed: content/public/android/java/src/org/chromium/content_public/browser/InputMethodManagerWrapper.java.