Research On Android Application Protection Technology Based On Self-modifying Code And Dynamic Loading

With the rapid development of mobile networks and the mobile phone industry,smart phones have become an indispensable part of people’s lives.The Android system as the most popular system in mobile terminals,its security issues have become increasingly prominent.The reverse engineering of the Android application seriously infringed the developer’s intellectual property rights and user’s privacy.In order to protect against attackers and protect the security of Android software,domestic and foreign scholars have proposed many Android software protection technologies,such as code obfuscation,shelling,and virtual machine protection.The birth of a new version of the ART virtual machine for Android has caused some of the original application protection solutions to be seriously affected,which is limited and not applicable any longer.In this paper,based on the deep analysis of the ART loading operation mechanism,the self-modification scheme under ART is studied and designed.The program uses the hook method to change the flow of loading DEX in applications,evades the conversion of the format during dynamic loading,and implements self-modifying repair at the appropriate time.Therefore,the inapplicable problems in original self-modification scheme caused by the new file structure under ART has been solved.And by using some experiments,the feasibility of the scheme is proved.Combining with the self-modifying state machine algorithm,the safety protection of the native code has been reached in the self-modification process,utilizing the separation of code blocks and transformation operations.And the static analysis and memory dump are effectively prevented.This paper studies the application of dynamic loading and self-modifying technology in software protection,and analyzes the software protection techniques under ART.Based on dynamic loading and self-modifying code,this paper proposes a software protection scheme that is still applicable to ART virtual machine.Combined dynamic loading technology,self-modifying technology and self-modified state machine algorithm,this scheme can provides effective protection to the key code in the application.By using method extraction and self-modification repair,the key code has been hidden to avoid the static analysis of reverse attackers,increasing the difficulty of its dynamic analysis extremely.Based on the analysis of the current application protection technology and the characteristics of ART,combined with anti-debugging,signature verification,integrity verification and other protection technologies,a complete set of application protection solutions has been designed and implemented.For this protection scheme,security and performance tests are conducted to evaluate this software protection scheme in the aspects of security and performance overhead etc.Experimental results show that the protection scheme of this paper has good feasibility and security.