CWE-939

Improper Authorization in Handler for Custom URL Scheme
AI Translation Available

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.

Status
incomplete
Abstraction
base
Mobile

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.

Common Consequences

access control other
Impacts
gain privileges or assume identity varies by context bypass protection mechanism

Detection Methods

automated static analysis

Potential Mitigations

Phases:
architecture and design
Descriptions:
• 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.