  Third-party security apps are an integral part of the Android app ecosystem.
Many users install them as an extra layer of protection for their devices.
There are hundreds of such security apps, both free and paid in Google Play
Store and some of them are downloaded millions of times. By installing security
apps, the smartphone users place a significant amount of trust towards the
security companies who developed these apps, because a fully functional mobile
security app requires access to many smartphone resources such as the storage,
text messages and email, browser history, and information about other installed
applications. Often these resources contain highly sensitive personal
information. As such, it is essential to understand the mobile security apps
ecosystem to assess whether is it indeed beneficial to install them. To this
end, in this paper, we present the first empirical study of Android security
apps. We analyse 100 Android security apps from multiple aspects such as
metadata, static analysis, and dynamic analysis and presents insights to their
operations and behaviours. Our results show that 20% of the security apps we
studied potentially resell the data they collect from smartphones to third
parties; in some cases, even without the user consent. Also, our experiments
show that around 50% of the security apps fail to identify malware installed on
a smartphone.
