@inproceedings{IsingPoddebniakKappertetal.2023,
  author    = {Ising, Fabian and Poddebniak, Damian and Kappert, Tobias and Saatjohann, Christoph and Schinzel, Sebastian},
  title     = {Content-Type: multipart/oracle -- Tapping into Format Oracles in Email End-to-End Encryption},
  series = {32nd USENIX Security Symposium},
  booktitle = {32nd USENIX Security Symposium},
  publisher = {USENIX Association},
  year      = {2023},
  abstract  = {S/MIME and OpenPGP use cryptographic constructions repeatedly shown to be vulnerable to format oracle attacks in protocols like TLS, SSH, or IKE. However, format oracle attacks in the End-to-End Encryption (E2EE) email setting are considered impractical as victims would need to open many attacker-modified emails and communicate the decryption result to the attacker. But is this really the case? In this paper, we survey how an attacker may remotely learn the decryption state in email E2EE. We analyze the interplay of MIME and IMAP and describe side-channels emerging from network patterns that leak the decryption status in Mail User Agents (MUAs). Concretely, we introduce specific MIME trees that produce decryption-dependent net work patterns when opened in a victim's email client. We survey 19 OpenPGP- and S/MIME-enabled email clients and four cryptographic libraries and uncover a side-channel leaking the decryption status of S/MIME messages in one client. Further, we discuss why the exploitation in the other clients is impractical and show that it is due to missing feature support and implementation quirks. These unintended defenses create an unfortunate conflict between usability and security. We present more rigid countermeasures for MUA developers and the standards to prevent exploitation.},
  language  = {en}
}
@inproceedings{EbbersIsingSaatjohannetal.2021,
  author    = {Ebbers, Simon and Ising, Fabian and Saatjohann, Christoph and Schinzel, Sebastian},
  title     = {Grand Theft App: Digital Forensics of Vehicle Assistant Apps},
  series = {ARES 2021: The 16th International Conference on Availability, Reliability and Security},
  booktitle = {ARES 2021: The 16th International Conference on Availability, Reliability and Security},
  doi       = {10.1145/3465481.3465754},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-139031},
  year      = {2021},
  abstract  = {Due to the increasing connectivity of modern vehicles, collected data is no longer only stored in the vehicle itself but also transmitted to car manufacturers and vehicle assistant apps. This development opens up new possibilities for digital forensics in criminal investigations involving modern vehicles. This paper deals with the digital forensic analysis of vehicle assistant apps of eight car manufacturers. We reconstruct the driver's activities based on the data stored on the smartphones and in the manufacturer's backend. For this purpose, data of the Android and iOS apps of the car manufacturers Audi, BMW, Ford, Mercedes, Opel, Seat, Tesla, and Volkswagen were extracted from the smartphone and examined using digital forensic methods following forensics guidelines. Additionally, manufacturer data was retrieved using Subject Access Requests. Using the extensive data gathered, we reconstruct trips and refueling processes, determine parking positions and duration, and track the locking and unlocking of the vehicle. Our findings show that the digital forensic investigation of smartphone applications is a useful addition to vehicle forensics and should therefore be taken into account in the strategic preparation of future digital forensic investigations.},
  language  = {en}
}
@inproceedings{SaatjohannIsingKringsetal.2020,
  author    = {Saatjohann, Christoph and Ising, Fabian and Krings, Luise and Schinzel, Sebastian},
  title     = {STALK: security analysis of smartwatches for kids},
  series = {ARES 2020: The 15th International Conference on Availability, Reliability and Security / Editors: Melanie Volkamer, Christian Wressnegger},
  booktitle = {ARES 2020: The 15th International Conference on Availability, Reliability and Security / Editors: Melanie Volkamer, Christian Wressnegger},
  isbn      = {978-1-4503-8833-7},
  doi       = {10.1145/3407023.3407037},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-123548},
  pages     = {1 -- 10},
  year      = {2020},
  abstract  = {Smart wearable devices become more and more prevalent in the age of the Internet of Things. While people wear them as fitness trackers or full-fledged smartphones, they also come in unique versions as smartwatches for children. These watches allow parents to track the location of their children in real-time and offer a communication channel between parent and child. In this paper, we analyzed six smartwatches for children and the corresponding backend platforms and applications for security and privacy concerns. We structure our analysis in distinct attacker scenarios and collect and describe related literature outside academic publications. Using a cellular network Man-in-the-Middle setup, reverse engineering, and dynamic analysis, we found several severe security issues, allowing for sensitive data disclosure, complete watch takeover, and illegal remote monitoring functionality.},
  language  = {en}
}