1. A method for masking data in a software application associated with a mobile computing device, the method comprising: receiving, by one or more computer processors, a request to display data in a software application on a mobile computing device; determining, by the one or more computer processors, whether one or more masking rules apply to the data, wherein determining whether one or more masking rules apply to the data is performed by masking functionality instrumented in an application binary of one or more application programming interfaces (APIs) used by the software application for at least data display or data input, and wherein instrumentation is implemented by adding instructions to the application binary of the one or more APIs used by the software application which are able to intercept the execution of the software application and enable masking of sensitive data prior to displaying sensitive data; responsive to determining that one or more masking rules apply to the data, masking, by the one or more computer processors, based on the one or more masking rules, the data, wherein masking is performed by the masking functionality instrumented in the application binary of the one or more APIs used by the software application; receiving, by the one or more computer processors, a request to perform a sensitive action on a screen of the mobile computing device; masking, by the one or more computer processors, the screen of the mobile computing device to prevent the sensitive action; and displaying, by the one or more computer processors, a message on the screen of the mobile computing device, wherein the message indicates that the user is not authorized to view the requested data.