Skip to content

Latest commit

 

History

History
55 lines (32 loc) · 6.36 KB

app_service.md

File metadata and controls

55 lines (32 loc) · 6.36 KB

App Service Security

Component Focus: Chromium's App Service, specifically the context menu handling in chrome/browser/ash/app_list/app_service/app_service_context_menu.cc.

Potential Logic Flaws:

  • Context Menu Vulnerabilities: Vulnerabilities in the app service context menu could allow malicious apps or extensions to execute arbitrary code, access sensitive data, or manipulate the user interface. The high VRP payout for app_service_context_menu.cc suggests that such vulnerabilities have been found in the past. The interaction with various components, such as the AppServiceProxy, CrostiniManager, and PluginVmManager, expands the attack surface.
  • Data Leakage: Sensitive information could be leaked through the context menu if not handled securely. The handling of user data and app metadata, especially during app info display and extension command execution, needs careful review.
  • Unauthorized Access: Malicious apps could potentially use the context menu to gain unauthorized access to system resources or user data. The ExecuteCommand function, which handles various commands including uninstalling apps and shutting down guest OSs, is a critical area for security. Proper permission checks and sandboxing are crucial.
  • UI Spoofing: The context menu's appearance or behavior could be spoofed to mislead users or trick them into performing unintended actions. The handling of dynamic menu items and app shortcuts needs careful review.
  • Race Conditions: Concurrent operations or asynchronous interactions with the app service could lead to race conditions, particularly in the ExecuteCommand function, which handles asynchronous operations like creating new windows and showing options pages.

Further Analysis and Potential Issues:

The app_service_context_menu.cc file handles context menu actions for apps in the ChromeOS app list. Key security considerations, based on the code analysis, include:

  • ExecuteCommand(): This function handles various context menu commands, including launching apps, showing app info, uninstalling apps, opening settings, shutting down guest OSs, and executing extension commands. The interaction with AppServiceProxy, CrostiniManager, PluginVmManager, and extension_menu_items_ introduces potential attack surfaces. Thorough analysis of this function is crucial, focusing on input validation, permission checks, and secure handling of potentially dangerous actions. The asynchronous execution of certain commands, such as creating new windows and showing options pages, introduces potential race conditions that need careful review.

  • OnGetMenuModel(): This function constructs the context menu, handling both default items and app-specific items provided by the AppServiceProxy. The handling of extension menu items and app shortcuts requires careful analysis to prevent malicious apps from injecting arbitrary menu items or manipulating their behavior. The build_extension_menu_before_default flag, specific to the FilesManager app, introduces a potential inconsistency that should be reviewed.

  • SetLaunchType(): This function handles setting the launch type for different app types (web apps, Chrome apps). The interaction with the AppServiceProxy and the AppListControllerDelegate needs review to ensure that launch type changes are handled securely and cannot be exploited by malicious apps.

  • ExecutePublisherContextMenuCommand(): This function executes custom context menu commands provided by app publishers. The handling of these commands, including input validation and permission checks, is crucial for security. The interaction with the AppServiceProxy needs careful review.

  • Inter-Process Communication (IPC): The AppServiceContextMenu interacts with various components through IPC, including the AppServiceProxy, which could introduce vulnerabilities if not handled securely. Message validation and authentication are essential for secure IPC.

  • Data Validation and Sanitization: All data received from apps or extensions, including menu item IDs, command IDs, and user data, should be validated and sanitized to prevent injection attacks.

  • Permission Checks: The code should enforce appropriate permission checks before allowing apps to perform potentially dangerous actions, such as uninstalling apps or shutting down guest OSs.

  • Resource Management: The code should properly manage resources, such as memory and file handles, to prevent leaks or exhaustion.

Areas Requiring Further Investigation:

  • Analyze the ExecuteCommand() function for input validation vulnerabilities, permission bypasses, and secure interaction with other components. Pay close attention to the asynchronous execution of commands and potential race conditions.
  • Review the OnGetMenuModel() function for secure handling of extension menu items and app shortcuts, preventing malicious injection or manipulation. Investigate the potential inconsistency introduced by the build_extension_menu_before_default flag.
  • Analyze the SetLaunchType() function for secure handling of launch type changes and interaction with the AppServiceProxy.
  • Review the ExecutePublisherContextMenuCommand() function for input validation, permission checks, and secure interaction with the AppServiceProxy.
  • Analyze the IPC mechanisms used by the AppServiceContextMenu for secure communication and message validation.
  • Investigate potential data leakage vulnerabilities related to the handling of user data and app metadata.
  • Review resource management for potential leaks or exhaustion.

Secure Contexts and App Service:

The app service and its context menu should be designed to operate securely within both secure (HTTPS) and insecure (HTTP) contexts. However, certain scenarios, such as handling sensitive data or interacting with extensions, might require additional security measures in insecure contexts.

Privacy Implications:

The app service context menu could potentially be used to leak sensitive user data or app metadata. Therefore, privacy-preserving design and implementation are crucial.

Additional Notes:

The high VRP payout associated with app_service_context_menu.cc highlights the importance of thorough security analysis for this component. Files reviewed: chrome/browser/ash/app_list/app_service/app_service_context_menu.cc.