A system and method whereby permission is accessed that is to be revoked for an application. The permission involves access to private data of a user via an API of an OS. It is determined, in the application, program point(s) involving access to the private data of the user via the API. For each selected one of the program point(s), code in the application is rewritten to replace a source statement, at the selected program point, that accesses the private data with another statement that allocates a mock object or value based on a type of an actual value returned by the source statement. The mock object or value does not expose the private data of the user. The application with the rewritten code is packaged as an output application able to be subsequently executed by the user, and is output for use by the user.