Characterizing android app signing issues

In the app releasing process, Android requires all apps to be digitally signed with a certificate before distribution. Android uses this certificate to identify the author and ensure the integrity of an app. However, a number of signature issues have been reported recently, threatening the security and privacy of Android apps. In this paper, we present the first large-scale systematic measurement study on issues related to Android app signatures. We first create a taxonomy covering four types of app signing issues (21 anti-patterns in total), including vulnerabilities, potential attacks, release bugs and compatibility issues. Then we developed an automated tool to characterize signature-related issues in over 5 million app items (3 million distinct apks) crawled from Google Play and 24 alternative Android app markets. Our empirical findings suggest that although Google has introduced apk-level signing schemes (V2 and V3) to overcome some of the known security issues, more than 93% of the apps still use only the JAR signing scheme (V1), which poses great security threats. Besides, we also revealed that 7% to 45% of the apps in the 25 studied markets have been found containing at least one signing issue, while a large number of apps have been exposed to security vulnerabilities, attacks and compatibility issues. Among them a considerable number of apps we identified are popular apps with millions of downloads. Finally, our evolution analysis suggested that most of the issues were not mitigated after a considerable amount of time across markets. The results shed light on the emergency for detecting and repairing the app signing issues.