TY - CHAP A1 - Poddebniak, Damian A1 - Ising, Fabian A1 - Böck, Hanno A1 - Schinzel, Sebastian T1 - Why TLS is better without STARTTLS: A Security Analysis of STARTTLS in the Email Context T2 - Proceedings of the 30th USENIX Security Symposium, August 11–13, 2021 N2 - TLS is one of today's most widely used and best-analyzed encryption technologies. However, for historical reasons, TLS for email protocols is often not used directly but negotiated via STARTTLS. This additional negotiation adds complexity and was prone to security vulnerabilities such as naive STARTTLS stripping or command injection attacks in the past. We perform the first structured analysis of STARTTLS in SMTP, POP3, and IMAP and introduce EAST, a semi-automatic testing toolkit with more than 100 test cases covering a wide range of variants of STARTTLS stripping, command and response injections, tampering attacks, and UI spoofing attacks for email protocols. Our analysis focuses on the confidentiality and integrity of email submission (email client to SMTP server) and email retrieval (email client to POP3 or IMAP server). While some of our findings are also relevant for email transport (from one SMTP server to another), the security implications in email submission and retrieval are more critical because these connections involve not only individual email messages but also user credentials that allow access to a user's email archive. We used EAST to analyze 28 email clients and 23 servers. In total, we reported over 40 STARTTLS issues, some of which allow mailbox spoofing, credential stealing, and even the hosting of HTTPS with a cross-protocol attack on IMAP. We conducted an Internet-wide scan for the particularly dangerous command injection attack and found that 320.000 email servers (2% of all email servers) are affected. Surprisingly, several clients were vulnerable to STARTTLS stripping attacks. In total, only 3 out of 28 clients did not show any STARTTLS-specific security issues. Even though the command injection attack received multiple CVEs in the past, EAST detected eight new instances of this problem. In total, only 7 out of 23 tested servers were never affected by this issue. We conclude that STARTTLS is error-prone to implement, under-specified in the standards, and should be avoided. Y1 - 2021 UR - https://www.usenix.org/conference/usenixsecurity21/presentation/poddebniak SN - 978-1-939133-24-3 VL - 2021 ER - TY - CHAP A1 - Schmitt, Isabell A1 - Schinzel, Sebastian T1 - WAFFle: Fingerprinting Filter Rules of Web Application Firewalls T2 - 6th USENIX Workshop on Offensive Technologies (WOOT 2012) Y1 - 2012 SP - 34 EP - 40 CY - Seattle. ER - TY - BOOK A1 - Schinzel, Sebastian T1 - Unintentional and Hidden Information Leaks in Networked Software Applications Y1 - 2012 SP - 1 EP - 103 CY - University of Erlangen-Nuernberg ET - Dissertation ER - TY - CHAP A1 - Saatjohann, Christoph A1 - Ising, Fabian A1 - Krings, Luise A1 - Schinzel, Sebastian T1 - STALK: security analysis of smartwatches for kids T2 - ARES 2020: The 15th International Conference on Availability, Reliability and Security / Editors: Melanie Volkamer, Christian Wressnegger N2 - 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. KW - Security KW - Privacy Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-123548 SN - 978-1-4503-8833-7 SP - 1 EP - 10 ER - TY - JOUR A1 - Schinzel, Sebastian T1 - Side Channel Attacks: Error messages and verbose log entries can tip off intruders JF - LINUX Magazine Y1 - 2012 IS - #143 ER - TY - CHAP A1 - Schinzel, Sebastian A1 - Schmucker, Martin A1 - Ebinger, Peter T1 - Security mechanisms of a legal peer-to-peer file sharing system (http://www.iadis.net/dl/Search_list_open.asp?code=6365) T2 - IADIS International Journal on Computer Science and Information Systems Y1 - 2009 ER - TY - CHAP A1 - Ebinger, Peter A1 - Schinzel, Sebastian A1 - Schmuckler, Martin T1 - Security mechanisms of a legal peer-to-peer file sharing system T2 - IADIS International Conference Applied Computing Y1 - 2008 ER - TY - CHAP A1 - Meyer, Christopher A1 - Somorovsky, Juraj A1 - Weiss, Eugen A1 - Schwenk, Jörg A1 - Schinzel, Sebastian A1 - Tews, Erik T1 - Revisiting SSL/TLS Implementations: New Bleichenbacher Side Channels and Attacks. T2 - 23rd USENIX Security Symposium (USENIX Security 14) Y1 - 2014 SN - ISBN 978-1-931971- SP - 733 EP - -748 PB - USENIX Association CY - San Diego, CA ER - TY - JOUR A1 - Gierling, Markus A1 - Saatjohann, Christoph A1 - Dresen, Christian A1 - Köbe, Julia A1 - Rath, Benjamin A1 - Eckardt, Lars A1 - Schinzel, Sebastian T1 - Reviewing Cyber Security Research of Implantable Medical Rhythm Devices regarding Patients’ Risk JF - 86. Jahrestagung und Herztage 2020 der DGK N2 - Introduction: The recent publication of several critical cyber security issues in cardiac implantable devices and the resulting press coverage upsets affected users and their trust in medical device producers. Reviewing the published security vulnerabilities regarding networked medical devices, it raises the question, if the reporting media, the responsible security researchers, and the producers handle security vulnerabilities appropriately. Are the media reports of security vulnerabilities in medical devices meaningful in a way that patients can assess their respective risk for an attack via the security vulnerability? The collaboration between IT-security experts and clinicians aims at reviewing published security vulnerabilities of rhythm devices, and evaluate overall patients risks. Methodology: We performed a literature review on security vulnerabilities in implantable medical devices with a focus on cardiac devices. We analyzed (Fig. 1) the (1) requirements for an attacker and the (2) technical feasibility and clustered them in three different scenarios: The first scenario requires that the attacker physically approaches a victim with a programming device. The second scenario requires proximity to the victim, e.g., within a few meters. The third and strongest attacker scenario is a remote attack that doesn’t require any physical proximity to the victim. We then compare the attacker scenarios and (3) the overall patients’ risks with the press coverage (overhyped, adequate, underhyped). (4) The resulting overall patients’ risk was rated by clinicians (security vulnerability of patients’ data, dangerous programming possible). Results: Out of the three analyzed incidents, we found one to be underhyped, one to be overhyped, and one was appropriate compared to the medial coverage (Fig. 2). The most occurring technical issues were based on the absence of basic security primitives. The patient damage for all of the analyzed incidents was fatal in the worst-case scenario. Further, the patient damage and the overall patient risks are disjunct due to the missing capability of performing large scale attacks. Conclusion: The resulting overall patients’ risks may not adequately reflect the patient damage in the considered cases. Often, the overall patient risk is not as severe as the necessary attacker capabilities are high and it would require strongly motivated attackers to perform the attack. Therefore, most of the reviewed cases are considered with a smaller overall patient risk than implied by press reports. Reviewing the ongoing IT-Security trends regarding implantable medical devices shows an increasing focus on researching in the field of medical device security. Therefore, further findings in the near future are to be expected. To deal with this fact in a responsible way, proper proactive knowledge management is mandatory. We recommend medical staff to critically reflect reports in mass media due to possible sensationalism. Therefore, we propose a joint approach in combining the technical expertise of cyber security experts with clinical aspects of medical experts, to ensure a solid understanding of a newly published vulnerability. The combination of both communities promises to result in better predictions for patients’ risks from security vulnerabilities in implanted cardiac devices. KW - Cyber Security KW - Cardiac Implantable Devices Y1 - 2020 U6 - http://dx.doi.org/10.1007/s00392-020-01621-0 VL - Band 109, Supplement 1, April 2020 SP - 1 EP - 2 ER - TY - CHAP A1 - Atkinson, Colin A1 - Gerbig, Ralph A1 - Barth, Florian A1 - Freiling, Felix A1 - Schinzel, Sebastian A1 - Hadasch, Frank A1 - Maedche, Alexander A1 - Müller, Benjamin T1 - Reducing the Incidence of Unintended, Human-Caused Information Flows in Enterprise Systems T2 - Enterprise Distributed Object Computing Conference Workshops (EDOCW), 2012 IEEE 16th International Y1 - 2012 U6 - http://dx.doi.org/10.1109/EDOCW.2012.12 SP - 11 EP - 18 ET - 3M4SE 2012 ER -