@incollection{PoddebniakDresenMuelleretal.2018, author = {Poddebniak, Damian and Dresen, Christian and M{\"u}ller, Jens and Ising, Fabian and Schinzel, Sebastian and Friedberg, Simon and Somorovsky, Juraj and Schwenk, J{\"o}rg}, title = {Efail: Breaking S/MIME and OpenPGP Email Encryption using Exfiltration Channels}, series = {USENIX Security 2018}, booktitle = {USENIX Security 2018}, edition = {27th}, address = {Baltimore, MD, USA}, isbn = {978-1-931971-46-1}, year = {2018}, language = {en} } @inproceedings{MuellerIsingMldadenovetal.2019, author = {M{\"u}ller, Jens and Ising, Fabian and Mldadenov, Vladislav and Mainka, Christian and Schinzel, Sebastian and Schwenk, J{\"o}rg}, title = {Practical Decryption exFiltration: Breaking PDF Encryption}, series = {The 26th ACM Conference on Computer and Communications, Security (CCS 2019), London, United Kingdom}, booktitle = {The 26th ACM Conference on Computer and Communications, Security (CCS 2019), London, United Kingdom}, doi = {10.1145/3319535.3354214}, year = {2019}, abstract = {The Portable Document Format, better known as PDF, is one of themost widely used document formats worldwide, and in order to en-sure information confidentiality, this file format supports documentencryption. In this paper, we analyze PDF encryption and showtwo novel techniques for breaking the confidentiality of encrypteddocuments. First, we abuse the PDF feature ofpartially encrypteddocuments to wrap the encrypted part of the document withinattacker-controlled content and therefore, exfiltrate the plaintextonce the document is opened by a legitimate user. Second, we abusea flaw in the PDF encryption specification to arbitrarily manipulateencrypted content. The only requirement is that a single block ofknown plaintext is needed, and we show that this is fulfilled bydesign. Our attacks allow the recovery of the entire plaintext of en-crypted documents by using exfiltration channels which are basedon standard compliant PDF properties.We evaluated our attacks on 27 widely used PDF viewers andfound all of them to be vulnerable. We responsibly disclosed thevulnerabilities and supported the vendors in fixing the issue}, language = {en} } @inproceedings{DresenIsingPoddebniaketal.2020, author = {Dresen, Christian and Ising, Fabian and Poddebniak, Damian and Kappert, Tobias and Holz, Thorsten and Schinzel, Sebastian}, title = {CORSICA: Cross-Origin Web Service Identification}, series = {The 15th ACM ASIA Conference on Computer and Communications Security}, booktitle = {The 15th ACM ASIA Conference on Computer and Communications Security}, editor = {Zhou, Jianying}, year = {2020}, abstract = {Vulnerabilities in private networks are difficult to detect for attackers outside of the network. While there are known methods for port scanning internal hosts that work by luring unwitting internal users to an external web page that hosts malicious JavaScript code, no such method for detailed and precise service identification is known. The reason is that the Same Origin Policy (SOP) prevents access to HTTP responses of other origins by default. We perform a structured analysis of loopholes in the SOP that can be used to identify web applications across network boundaries. For this, we analyze HTML5, CSS, and JavaScript features of standard-compliant web browsers that may leak sensitive information about cross-origin content. The results reveal several novel techniques, including leaking JavaScript function names or styles of cross-origin requests that are available in all common browsers. We implement and test these techniques in a tool called CORSICA. It can successfully identify 31 of 42 (74\%) of web services running on different IoT devices as well as the version numbers of the four most widely used content management systems WordPress, Drupal, Joomla, and TYPO3. CORSICA can also determine the patch level on average down to three versions (WordPress), six versions (Drupal), two versions (Joomla), and four versions (TYPO3) with only ten requests on average. Furthermore, CORSICA is able to identify 48 WordPress plugins containing 65 vulnerabilities. Finally, we analyze mitigation strategies and show that the proposed but not yet implemented strategies Cross-Origin Resource Policy (CORP)} and Sec-Metadata would prevent our identification techniques.}, 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} } @article{GierlingSaatjohannDresenetal.2020, author = {Gierling, Markus and Saatjohann, Christoph and Dresen, Christian and K{\"o}be, Julia and Rath, Benjamin and Eckardt, Lars and Schinzel, Sebastian}, title = {Reviewing Cyber Security Research of Implantable Medical Rhythm Devices regarding Patients' Risk}, series = {86. Jahrestagung und Herztage 2020 der DGK}, volume = {Band 109, Supplement 1, April 2020}, journal = {86. Jahrestagung und Herztage 2020 der DGK}, doi = {10.1007/s00392-020-01621-0}, pages = {1 -- 2}, year = {2020}, abstract = {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.}, language = {en} } @inproceedings{GierlingDresenEichetal.2018, author = {Gierling, Markus and Dresen, Christian and Eich, Hans and Mittman, Karin and Schinzel, Sebastian and Haverkamp, Uwe}, title = {Analysis and consequences of an imaging process concerning the cyber security of a networked computer tomography scanner}, series = {STRAHLENTHERAPIE UND ONKOLOGIE}, booktitle = {STRAHLENTHERAPIE UND ONKOLOGIE}, pages = {185 -- 186}, year = {2018}, language = {en} } @inproceedings{MuellerIsingMla­de­novetal.2020, author = {M{\"u}ller, Jens and Ising, Fabian and Mla­de­nov, Vla­dis­lav and Mainka, Chris­ti­an and Schinzel, Sebastian and Schwenk, J{\"o}rg}, title = {Of­fice Do­cu­ment Se­cu­ri­ty and Pri­va­cy}, series = {14th USE­NIX Work­shop on Of­fen­si­ve Tech­no­lo­gies (WOOT 2020)}, booktitle = {14th USE­NIX Work­shop on Of­fen­si­ve Tech­no­lo­gies (WOOT 2020)}, publisher = {USENIX}, year = {2020}, abstract = {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.}, language = {en} } @inproceedings{WillingDresenHaverkampetal.2020, author = {Willing, Markus and Dresen, Christian and Haverkamp, Uwe and Schinzel, Sebastian}, title = {Analyzing medical device connectivity and its effect on cyber security in german hospitals}, publisher = {BMC Medical Informatics and Decision Making volume}, doi = {10.1186/s12911-020-01259-y}, year = {2020}, abstract = {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.}, language = {en} } @inproceedings{PuschnerSaatjohannWillingetal.2021, author = {Puschner, Endres and Saatjohann, Christoph and Willing, Markus and Dresen, Christian and K{\"o}be, Julia and Rath, Benjamin and Paar, Christof and Eckardt, Lars and Haverkamp, Uwe and Schinzel, Sebastian}, title = {Listen to Your Heart: Evaluation of the Cardiologic Ecosystem}, 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 = {10.1145/3465481.3465753}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-139012}, year = {2021}, abstract = {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.}, 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} }