A Study on the Testing of Android Security Patches

Android controls the majority of the global OS market. Android Open Source Project (AOSP) is a very complex system with many layers including the apps, the Application Framework, the middle-ware, the customized Linux kernel, and the trusted components. Although security is implemented in every layer, the Application Framework forms an important of the attack surface due to managing the user interface and permissions. Android security has evolved over the years. The security flaws that have been found in the Application Framework led to a redesign of Android permissions. Part of this evolution includes fixes to the vulnerabilities that are publicly released in the monthly Android security bulletins. In this study, we analyze the CVEs listed in the Android security bulletin within the last 6 years. We focus on the Android application framework and investigate several research questions relating to 1) the security relevant components, 2) the type and amount of testing information for the security patches, and 3) the adequacy of the tests designed to test these patches. Our findings indicate that Android security testing practices can be further improved by designing security bulletin update specific tests, and by improving code coverage of patched files.