Meta and Media Data Stream Forensics in the Encrypted Domain of Video Conferences

Our paper presents a systematic approach to investigate whether and how events can be identified and extracted during the use of video conferencing software. Our approach is based on the encrypted meta and multimedia data exchanged during video conference sessions. It relies on the network data stream which contains data interpretable without decryption (plain data) and encrypted data (encrypted content) some of which is decrypted using our approach (decrypted content). This systematic approach uses a forensic process model and the fission of network data streams before applying methods on the specific individual data types. Our approach is applied exemplary to the Zoom Videoconferencing Service with Client Version 5.4.57862.0110 [4], the mobile Android App Client Version 5.5.2 (1328) [4], the webbased client and the servers (accessed between Jan 21st and Feb 4th). The investigation includes over 50 different configurations. For the heuristic speaker identification, two series of nine sets for eight different speakers are collected. The results show that various user data can be derived from characteristics of encrypted media streams, even if end-to-end encryption is used. The findings suggest user privacy risks. Our approach offers the identification of various events, which enable activity tracking (e.g. camera on/off, increased activity in front of camera) by evaluating heuristic features of the network streams. Further research into user identification within the encrypted audio stream based on pattern recognition using heuristic features of the corresponding network data stream is conducted and suggests the possibility to identify users within a specific set.