A method and system for application security. The methods and systems of the present disclosure improve application security and may be used to secure a host application and operating system from malicious fast applications. A request to access resources of the computing device is received from an application adapter of a fast application operating within a host application on the computing device. In response to a determination that the request is associated with resources included in a permission list of the fast application, the unique user identifier (UID) of the application adapter to the UID of the host application is translated by the operating system, which determines whether to allow the request based on the UID of the host application. Otherwise, the operating system determines whether to allow the request based on the UID of the application adapter.