Characterizing Mobile Applications Through Analysis of DNS Traffic

User privacy may remain vulnerable when using encrypted communication protocols, such as HTTPS, if DNS queries are sent in cleartext over UDP port 53 (Do53). In this study, we demonstrate the possibility of characterizing the mobile application a user is using based on its Do53 traffic. By analyzing a dataset of traffic captured from 80 Android mobile apps, we can identify the app being used based on its DNS queries with an accuracy of 88.75%. While modern operating systems, including Android since version 9.0, support encrypted DNS traffic, this feature is not enabled by default and relies on the DNS provider's support. Moreover, even when DNS traffic is encrypted, the DNS service provider still has access to our queries and could potentially extract information from them.