  Modern applications are end-to-end encrypted to prevent data from being read
or secretly modified. 5G tech nology provides ubiquitous access to these
applications without compromising the application-specific performance and
latency goals. In this paper, we empirically demonstrate that 5G radio
communication becomes the side channel to precisely infer the user's
applications in real-time. The key idea lies in observing the 5G physical and
MAC layer interactions over time that reveal the application's behavior. The
MAC layer receives the data from the application and requests the network to
assign the radio resource blocks. The network assigns the radio resources as
per application requirements, such as priority, Quality of Service (QoS) needs,
amount of data to be transmitted, and buffer size. The adversary can passively
observe the radio resources to fingerprint the applications. We empirically
demonstrate this attack by considering four different categories of
applications: online shopping, voice/video conferencing, video streaming, and
Over-The-Top (OTT) media platforms. Finally, we have also demonstrated that an
attacker can differentiate various types of applications in real-time within
each category.
