Abstract: Among various types of mobile apps, mobile utility apps are increasingly becoming data-driven, and these apps tend to collect a significant amount of app usage data to carry out their promised utilities and enhance user experiences. A part of such app usage data often contains security-sensitive information. Thus, an important and challenging issue arises: how to balance between the user’s privacy and the utility app’s utility functionality. We propose techniques to enable users to determine what original values to keep in sanitized data in order to deliver a desirable level of utility efficacy. To accomplish our goal, we (1) incorporate user assistance for app exploration and abnormal-behavior detection, (2) support user validation of malicious-app candidates via program-repair techniques, and (3) sanitize users’ app usage data to balance between privacy preservation and utility efficacy.