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Weakness (CWE)

CWE-939: Improper Authorization in Handler for Custom URL Scheme

Base Incomplete

The product uses a handler for a custom URL scheme, but it does not properly restrict which actors can invoke the handler using the scheme.

More detail

Mobile platforms and other architectures allow the use of custom URL schemes to facilitate communication between applications. In the case of iOS, this is the only method to do inter-application communication. The implementation is at the developer's discretion which may open security flaws in the application. An example could be potentially dangerous functionality such as modifying files through a custom URL scheme.

How to prevent it (1 mitigation)
  1. Architecture and Design

    Utilize a user prompt pop-up to authorize potentially harmful actions such as those modifying data or dealing with sensitive information.

    When designing functionality of actions in the URL scheme, consider whether the action should be accessible to all mobile applications, or if an allowlist of applications to interface with is appropriate.

Source: MITRE CWE-939

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