TY - CHAP A1 - Müller, Jens A1 - Ising, Fabian A1 - Mla­de­nov, Vla­dis­lav A1 - Mainka, Chris­ti­an A1 - Schinzel, Sebastian A1 - Schwenk, Jörg T1 - Of­fice Do­cu­ment Se­cu­ri­ty and Pri­va­cy T2 - 14th USE­NIX Work­shop on Of­fen­si­ve Tech­no­lo­gies (WOOT 2020) N2 - OOXML and ODF are the de facto standard data formats for word processing, spreadsheets, and presentations. Both are XML-based, feature-rich container formats dating back to the early 2000s. In this work, we present a systematic analysis of the capabilities of malicious office documents. Instead of focusing on implementation bugs, we abuse legitimate features of the OOXML and ODF specifications. We categorize our attacks into five classes: (1) Denial-of-Service attacks affecting the host on which the document is processed. (2) Invasion of privacy attacks that track the usage of the document. (3) Information disclosure attacks exfiltrating personal data out of the victim's computer. (4) Data manipulation on the victim's system. (5) Code execution on the victim's machine. We evaluated the reference implementations – Microsoft Office and LibreOffice – and found both of them to be vulnerable to each tested class of attacks. Finally, we propose mitigation strategies to counter these attacks. KW - Cyber Security KW - Open Document Format KW - docx Y1 - 2020 UR - https://www.usenix.org/conference/woot20/presentation/muller PB - USENIX ER - TY - CHAP A1 - Willing, Markus A1 - Dresen, Christian A1 - Haverkamp, Uwe A1 - Schinzel, Sebastian T1 - Analyzing medical device connectivity and its effect on cyber security in german hospitals N2 - Background: Modern healthcare devices can be connected to computer networks and many western healthcareinstitutions run those devices in networks. At the same time, cyber attacks are on the rise and there is evidence thatcybercriminals do not spare critical infrastructure such as major hospitals, even if they endanger patients. Intuitively,the more and closer connected healthcare devices are to public networks, the higher the risk of getting attacked. Methods: To asses the current connectivity status of healthcare devices, we surveyed the field of German hospitalsand especially University Medical Center UMCs. Results: The results show a strong correlation between the networking degree and the number of medical devices.The average number of medical devices is 25.150, with a median of networked medical devices of 3.600. Actual keyusers of networked medical devices are the departments Radiology, Intensive Care, Radio-Oncology RO, NuclearMedicine NUC, and Anaesthesiology in the group of UMCs. In the next five years, the usage of networked medicaldevices will increase significantly in the departments of Surgery, Intensive Care, and Radiology. We detected a strongcorrelation between the degree of connectivity and the likelihood of being attacked.The survey answers regarding the cyber security status reveal a lack of security basics in some of the inquiredhospitals. We did discover successful attacks in hospitals with separated or subsidiary departments. A fusion ofcompetencies on an organizational level facilitates the right behavior here. Most hospitals rated themselvespredominantly positively in the self-assessment but also stated the usefulness of IT security insurance.Conclusions:Concluding our results, hospitals are already facing the consequences of omitted measures within theirgrowing pool of medical devices. Continuously relying on historically grown structures without adaption and trustingmanufactures to solve vectors is a critical behavior that could seriously endanger patients. Y1 - 2020 U6 - http://dx.doi.org/10.1186/s12911-020-01259-y PB - BMC Medical Informatics and Decision Making volume ER - TY - CHAP A1 - Puschner, Endres A1 - Saatjohann, Christoph A1 - Willing, Markus A1 - Dresen, Christian A1 - Köbe, Julia A1 - Rath, Benjamin A1 - Paar, Christof A1 - Eckardt, Lars A1 - Haverkamp, Uwe A1 - Schinzel, Sebastian T1 - Listen to Your Heart: Evaluation of the Cardiologic Ecosystem T2 - ARES 2021: The 16th International Conference on Availability, Reliability and Security N2 - Modern implantable cardiologic devices communicate via radio frequency techniques and nearby gateways to a backend server on the internet. Those implanted devices, gateways, and servers form an ecosystem of proprietary hardware and protocols that process sensitive medical data and is often vital for patients’ health. This paper analyzes the security of this Ecosystem, from technical gateway aspects, via the programmer, to configure the implanted device, up to the processing of personal medical data from large cardiological device producers. Based on a real-world attacker model, we evaluated different devices and found several severe vulnerabilities. Furthermore, we could purchase a fully functional programmer for implantable cardiological devices, allowing us to re-program such devices or even induce electric shocks on untampered implanted devices. Additionally, we sent several Art. 15 and Art. 20 GDPR inquiries to manufacturers of implantable cardiologic devices, revealing non-conforming processes and a lack of awareness about patients’ rights and companies’ obligations. This, and the fact that many vulnerabilities are still to be found after many vulnerability disclosures in recent years, present a worrying security state of the whole ecosystem. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-139012 ER - TY - CHAP A1 - Ebbers, Simon A1 - Ising, Fabian A1 - Saatjohann, Christoph A1 - Schinzel, Sebastian T1 - Grand Theft App: Digital Forensics of Vehicle Assistant Apps T2 - ARES 2021: The 16th International Conference on Availability, Reliability and Security N2 - 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. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-139031 ER - 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 - JOUR A1 - Brinkmann, Marcus A1 - Dresen, Christian A1 - Merget, Robert A1 - Poddebniak, Damian A1 - Müller, Jens A1 - Somorovsky, Juraj A1 - Schwenk, Jörg A1 - Schinzel, Sebastian T1 - ALPACA: Application Layer Protocol Confusion - Analyzing and Mitigating Cracks in TLS Authentication JF - 30th USENIX Security Symposium Y1 - 2021 UR - https://www.usenix.org/conference/usenixsecurity21/presentation/brinkmann ER - TY - CHAP A1 - Willing, Markus A1 - Saatjohann, Christoph A1 - Rath, Benjamin A1 - Schinzel, Sebastian A1 - Eckardt, Lars A1 - Köbe, Julia T1 - Experiences with General Data Protection Regulations and Remote Monitoring of Implantable Rhythm Devices T2 - 87. Jahrestagung der Deutsche Gesellschaft für Kardiologie – Herz‑ und Kreislauforschung e.V Y1 - 2021 U6 - http://dx.doi.org/10.1007/s00392-021-01843-w PB - Springer-Verlag GmbH ER - TY - JOUR A1 - Willing, Markus A1 - Dresen, Christian A1 - Gerlitz, Eva A1 - Haering, Maximilian A1 - Smith, Matthew A1 - Binnewies, Carmen A1 - Guess, Tim A1 - Haverkamp, Uwe A1 - Schinzel, Sebastian T1 - Behavioral responses to a cyber attack in a hospital environment JF - Nature -- Scientific Reports N2 - Technical and organizational steps are necessary to mitigate cyber threats and reduce risks. Human behavior is the last line of defense for many hospitals and is considered as equally important as technical security. Medical staff must be properly trained to perform such procedures. This paper presents the first qualitative, interdisciplinary research on how members of an intermediate care unit react to a cyberattack against their patient monitoring equipment. We conducted a simulation in a hospital training environment with 20 intensive care nurses. By the end of the experiment, 12 of the 20 participants realized the monitors’ incorrect behavior. We present a qualitative behavior analysis of high performing participants (HPP) and low performing participants (LPP). The HPP showed fewer signs of stress, were easier on their colleagues, and used analog systems more often than the LPP. With 40% of our participants not recognizing the attack, we see room for improvements through the use of proper tools and provision of adequate training to prepare staff for potential attacks in the future. Y1 - 2021 U6 - http://dx.doi.org/10.1038/s41598-021-98576-7 ER - TY - CHAP A1 - Saatjohann, Christoph A1 - Ising, Fabian A1 - Gierlings, Matthias A1 - Noss, Dominik A1 - Schimmler, Sascha A1 - Klemm, Alexander A1 - Grundmann, Leif A1 - Frosch, Tilman A1 - Schinzel, Sebastian T1 - Sicherheit medizintechnischer Protokolle im Krankenhaus T2 - SICHERHEIT 2022. Hrsg. Christian Wressnegger, Delphine Reinhardt, Thomas Barber, Bernhard C. Witt, Daniel Arp, Zoltan Mann N2 - Medizinische Einrichtungen waren in den letzten Jahren immer wieder von Cyber-Angriffen betroffen. Auch wenn sich diese Angriffe derzeit auf die Office-IT-Infrastruktur der Einrichtungen konzentrieren, existiert mit medizinischen Systemen und Kommunikationsprotokollen eine weitere wenig beachtete Angriffsoberfläche. In diesem Beitrag analysieren wir die weit verbreiteten medizintechnischen Kommunikations-Protokolle DICOM und HL7 sowie Protokoll-Implementierungen auf ihre IT-Sicherheit. Dafür präsentieren wir die Ergebnisse der Sicherheitsanalyse der DICOM- und HL7-Standards, einen Fuzzer “MedFUZZ” für diese Protokolle sowie einen Schwachstellenscanner “MedVAS”, der Schwachstellen in medizintechnischen Produktivumgebungen auffinden kann. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-150072 SN - 978-3-88579-717-3 SN - 1617-5468 PB - Gesellschaft für Informatik e.V. CY - Bonn ER - TY - CHAP A1 - Mayer, Peter A1 - Poddebniak, Damian A1 - Fischer, Konstantin A1 - Brinkmann, Marcus A1 - Somorovsky, Juraj A1 - Schinzel, Sebastian A1 - Volkamer, Melanie T1 - "I don’t know why I check this...'' - Investigating Expert Users' Strategies to Detect Email Signature Spoofing Attacks T2 - Eighteenth Symposium on Usable Privacy and Security (SOUPS 2022) N2 - OpenPGP is one of the two major standards for end-to-end email security. Several studies showed that serious usability issues exist with tools implementing this standard. However, a widespread assumption is that expert users can handle these tools and detect signature spoofing attacks. We present a user study investigating expert users' strategies to detect signature spoofing attacks in Thunderbird. We observed 25 expert users while they classified eight emails as either having a legitimate signature or not. Studying expert users explicitly gives us an upper bound of attack detection rates of all users dealing with PGP signatures. 52% of participants fell for at least one out of four signature spoofing attacks. Overall, participants did not have an established strategy for evaluating email signature legitimacy. We observed our participants apply 23 different types of checks when inspecting signed emails, but only 8 of these checks tended to be useful in identifying the spoofed or invalid signatures. In performing their checks, participants were frequently startled, confused, or annoyed with the user interface, which they found supported them little. All these results paint a clear picture: Even expert users struggle to verify email signatures, usability issues in email security are not limited to novice users, and developers may need proper guidance on implementing email signature GUIs correctly. Y1 - 2022 UR - https://www.usenix.org/conference/soups2022/presentation/mayer SN - 978-1-939133-30-4 SP - 77 EP - 96 PB - USENIX Association CY - Boston, MA ER -