| With the rapid development of mobile Internet,Android smart devices have gradually become an indispensable part of people’s lives.Android smart devices store a large number of user privacy information while providing users with rich features,such as calling records,contacts,e-mail information,account password,etc.,which makes them main targets of some attackers.Malicious applications aiming at stealing user privacy emerge in an endless stream.In addition,the coarse-grained defects of Android permission mechanism also worsen the user privacy issues.Therefore,to research on how to reinforce the security mechanisms so as to protect user privacy better is of great significance and application value.This paper mainly studies on the technology of privacy protection for Android users.The main contents are as follows.Aiming at the problem that Android cannot implement fine-grained control over the application permissions,this paper proposes a method of permission policy enforcement for Android applications based on reverse engineering.The target application software is analyzed for its sensitive system call function set,and each system call function in the set is instrumented to redirect to the security controller when permission request is triggered.The security controller performs a policy matching operation on each system call function and the application will behave according to the search results,which enables users to control the using permission of the application.In view of the fact that Android permission mechanism cannot effectively prevent the application from malicious code attack,this paper proposes a context-based security enhancement scheme.The permission mechanism is enhanced so that when the applications trigger using permission request,it checks out not only whether the application has the requested permission or not,but also the corresponding context.By utilizing the context information to identify the real origin of using permission request,the system can effectively prevent intra-app malicious code attacks.At last,we extended the Android system to implement a user privacy protection system based on the context-related permission model.Experimental results show that the designed user privacy protection system can have a fine-grained control over permission use,and thus better protect user privacy. |
