@incollection{MeyerSomorovskyWeissetal.2014, author = {Meyer, Christopher and Somorovsky, Juraj and Weiss, Eugen and Schwenk, J{\"o}rg and Schinzel, Sebastian and Tews, Erik}, title = {Revisiting SSL/TLS Implementations: New Bleichenbacher Side Channels and Attacks.}, series = {23rd USENIX Security Symposium (USENIX Security 14)}, booktitle = {23rd USENIX Security Symposium (USENIX Security 14)}, publisher = {USENIX Association}, address = {San Diego, CA}, isbn = {ISBN 978-1-931971-}, pages = {733 -- -748}, year = {2014}, language = {en} } @article{SchinzelThuenemannLoehr2014, author = {Schinzel, Sebastian and Th{\"u}nemann, Maximilian and L{\"o}hr, Dennis}, title = {Internetzensus - Das Internet scannen und auf Schwachstellen untersuchen}, series = {iX - Security kompakt}, journal = {iX - Security kompakt}, number = {4}, issn = {4018837005}, year = {2014}, language = {de} } @incollection{AviramSchinzelSomorovskyetal.2016, author = {Aviram, Nimrod and Schinzel, Sebastian and Somorovsky, Juraj and Heninger, Nadia and Dankel, Maik and Steube, Jens and Valenta, Luke and Adrian, David and Halderman, J. Alex and Dukhovni, Viktor and K{\"a}sper, Emilia and Cohney, Shaanan and Engels, Susanne and Paar, Christof and Shavitt, Yuval}, title = {DROWN: Breaking TLS Using SSLv2}, series = {25th Usenix Security Symposium}, booktitle = {25th Usenix Security Symposium}, publisher = {Usenix Association.}, address = {Austin, TX.}, pages = {689 -- 706}, year = {2016}, language = {mul} } @incollection{SchmittSchinzel2012, author = {Schmitt, Isabell and Schinzel, Sebastian}, title = {WAFFle: Fingerprinting Filter Rules of Web Application Firewalls}, series = {6th USENIX Workshop on Offensive Technologies (WOOT 2012)}, booktitle = {6th USENIX Workshop on Offensive Technologies (WOOT 2012)}, address = {Seattle.}, pages = {34 -- 40}, year = {2012}, language = {en} } @incollection{JagerSchinzelSomorovsky2012, author = {Jager, Tibor and Schinzel, Sebastian and Somorovsky, Juraj}, title = {Bleichenbacher's Attack Strinkes Again: Breaking PKCS\#1 v1.5 in XML Encryption}, series = {17th European Symposium on Research in Computer Security (ESORCIS 2012)}, booktitle = {17th European Symposium on Research in Computer Security (ESORCIS 2012)}, year = {2012}, language = {mul} } @incollection{FreilingSchinzel2011, author = {Freiling, Felix and Schinzel, Sebastian}, title = {Detecting Hidden Storage Side Channel Vulnerabilities in Networked Applications}, series = {IFIP sec2011 - Future Challenges in Security and Privacy for Academia and Industry}, booktitle = {IFIP sec2011 - Future Challenges in Security and Privacy for Academia and Industry}, edition = {Volume 354}, publisher = {Springer, Berlin, Heidelberg}, isbn = {978-3-642-21423-3}, doi = {10.1007/978-3-642-21424-0_4}, pages = {41 -- 55}, year = {2011}, language = {de} } @incollection{Schinzel2011, author = {Schinzel, Sebastian}, title = {An Efficient Mitigation Method for Timing Side Channels on the Web}, series = {2nd International Workshop on Constructive Side-Channel Analysis and Secure Design (COSADE 2011)}, booktitle = {2nd International Workshop on Constructive Side-Channel Analysis and Secure Design (COSADE 2011)}, year = {2011}, language = {en} } @article{SchinzelSchmitt2012, author = {Schinzel, Sebastian and Schmitt, Isabell}, title = {{\"U}ber Umwege - Seitenkanalangriffe auf Netzwerkanwendungen}, series = {iX - Magazin f{\"u}r professionelle Informationstechnik}, journal = {iX - Magazin f{\"u}r professionelle Informationstechnik}, number = {11}, year = {2012}, language = {mul} } @article{SchinzelWeidemannWiegensteinetal.2011, author = {Schinzel, Sebastian and Weidemann, Frederik and Wiegenstein, Andreas and Schumacher, Markus}, title = {SAP-Security - Sicherheitsl{\"o}cher in eigenem ABAP-Code stopfen}, series = {iX - Magazin f{\"u}r professionelle Informationstechnik}, journal = {iX - Magazin f{\"u}r professionelle Informationstechnik}, number = {07}, year = {2011}, language = {mul} } @incollection{AtkinsonGerbigBarthetal.2012, author = {Atkinson, Colin and Gerbig, Ralph and Barth, Florian and Freiling, Felix and Schinzel, Sebastian and Hadasch, Frank and Maedche, Alexander and M{\"u}ller, Benjamin}, title = {Reducing the Incidence of Unintended, Human-Caused Information Flows in Enterprise Systems}, series = {Enterprise Distributed Object Computing Conference Workshops (EDOCW), 2012 IEEE 16th International}, booktitle = {Enterprise Distributed Object Computing Conference Workshops (EDOCW), 2012 IEEE 16th International}, edition = {3M4SE 2012}, doi = {10.1109/EDOCW.2012.12}, pages = {11 -- 18}, year = {2012}, language = {en} } @incollection{SchinzelSchmuckerEbinger2009, author = {Schinzel, Sebastian and Schmucker, Martin and Ebinger, Peter}, title = {Security mechanisms of a legal peer-to-peer file sharing system (http://www.iadis.net/dl/Search_list_open.asp?code=6365)}, series = {IADIS International Journal on Computer Science and Information Systems}, booktitle = {IADIS International Journal on Computer Science and Information Systems}, year = {2009}, language = {en} } @incollection{EbingerSchinzelSchmuckler2008, author = {Ebinger, Peter and Schinzel, Sebastian and Schmuckler, Martin}, title = {Security mechanisms of a legal peer-to-peer file sharing system}, series = {IADIS International Conference Applied Computing}, booktitle = {IADIS International Conference Applied Computing}, year = {2008}, language = {en} } @article{Schinzel2012, author = {Schinzel, Sebastian}, title = {Side Channel Attacks: Error messages and verbose log entries can tip off intruders}, series = {LINUX Magazine}, journal = {LINUX Magazine}, number = {\#143}, year = {2012}, language = {en} } @article{Schinzel2012, author = {Schinzel, Sebastian}, title = {Seitenkan{\"a}le mit Untiefen: Manche Webanwendungen spielen Angreifern unfreiwillig Informationen zu}, series = {ADMIN Magazin}, journal = {ADMIN Magazin}, year = {2012}, language = {de} } @incollection{BauerSchinzelFelixetal.2016, author = {Bauer, Johannes and Schinzel, Sebastian and Felix, C. and Freiling, Andreas}, title = {Information leakage behind the curtain: Abusing anti-EMI features for covert communication}, series = {Hardware Oriented Security and Trust (HOST), 2016 IEEE International Symposium on}, booktitle = {Hardware Oriented Security and Trust (HOST), 2016 IEEE International Symposium on}, doi = {10.1109/HST.2016.7495570}, pages = {130 -- 134}, year = {2016}, language = {en} } @book{Schinzel2012, author = {Schinzel, Sebastian}, title = {Unintentional and Hidden Information Leaks in Networked Software Applications}, edition = {Dissertation}, address = {University of Erlangen-Nuernberg}, pages = {1 -- 103}, year = {2012}, language = {en} } @incollection{BenensonDewaldEsseretal.2011, author = {Benenson, Zinaida and Dewald, Andreas and Eßer, Hans-J{\"u}rgen and Felix, C. and Freiling, Tilo and M{\"u}ller, Christian and Moch, Stefan and Vomel, Sebastian and Schinzel, Miachel and Spreitzenbach, Ben}, title = {Exploring the Landscape of Cybercrime}, series = {SysSec Workshop (SysSec), 2011 First}, booktitle = {SysSec Workshop (SysSec), 2011 First}, doi = {10.1109/SysSec.2011.23}, year = {2011}, language = {en} } @incollection{WiegensteinSchumacherSchinzeletal.2009, author = {Wiegenstein, Andreas and Schumacher, Markus and Schinzel, Sebastian and Weidemann, Frederik}, title = {Sichere ABAP-Programmierung}, series = {Rheinwerk Verlag GmbH}, booktitle = {Rheinwerk Verlag GmbH}, isbn = {978-3-8362-1357-8}, pages = {1 -- 372}, year = {2009}, language = {de} } @incollection{GoetzfriedEckertMuelleretal.2017, author = {G{\"o}tzfried, J. and Eckert, M. and M{\"u}ller, T. and Schinzel, S.}, title = {Cache Attacks on Intel SGX}, series = {EuroSec'17}, booktitle = {EuroSec'17}, publisher = {ACM}, address = {Belgrade, Serbia}, isbn = {978-1-4503-4935-2/}, doi = {10.1145/3065913.3065915}, year = {2017}, language = {mul} } @incollection{SchumiloAschermannGawliketal.2017, author = {Schumilo, Sergej and Aschermann, Cornelius and Gawlik, Robert and Schinzel, Sebastian and Holz, Thorsten}, title = {kAFL: Hardware-Assisted Feedback Fuzzing for OS Kernels}, series = {26th Usenix Security Symposium}, booktitle = {26th Usenix Security Symposium}, year = {2017}, language = {en} } @incollection{PoddebniakSomorovskySchinzeletal.2018, author = {Poddebniak, Damian and Somorovsky, Juraj and Schinzel, Sebastian and Lochter, Manfred and R{\"o}sler, Paul}, title = {Attacking Deterministic Signature Schemes using Fault Attacks}, series = {3rd IEEE European Symposium on Security and Privacy}, booktitle = {3rd IEEE European Symposium on Security and Privacy}, year = {2018}, language = {mul} } @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{MuellerBrinkmannPoddebniaketal.2019, author = {M{\"u}ller, Jens and Brinkmann, Marcus and Poddebniak, Damian and B{\"o}ck, Hanno and Schinzel, Sebastian and Smomrosvsky, Juraj and Schwenk, J{\"o}rg}, title = {"Johnny, you are fired!" - Spoofing OpenPGP and S/MIME Signatures in Emails}, series = {28th Usenix Security Symposium, Santa Clara, CA, USA}, booktitle = {28th Usenix Security Symposium, Santa Clara, CA, USA}, year = {2019}, abstract = {OpenPGP and S/MIME are the two major standards to en-crypt and digitally sign emails. Digital signatures are sup-posed to guarantee authenticity and integrity of messages. Inthis work we show practical forgery attacks against variousimplementations of OpenPGP and S/MIME email signatureverification in five attack classes: (1) We analyze edge casesin S/MIME's container format. (2) We exploit in-band sig-naling in the GnuPG API, the most widely used OpenPGPimplementation. (3) We apply MIME wrapping attacks thatabuse the email clients' handling of partially signed mes-sages. (4) We analyze weaknesses in the binding of signedmessages to the sender identity. (5) We systematically testemail clients for UI redressing attacks.Our attacks allow the spoofing of digital signatures for ar-bitrary messages in 14 out of 20 tested OpenPGP-capableemail clients and 15 out of 22 email clients supportingS/MIME signatures. While the attacks do not target the un-derlying cryptographic primitives of digital signatures, theyraise concerns about the actual security of OpenPGP andS/MIME email applications. Finally, we propose mitigationstrategies to counter these attacks.}, language = {de} } @inproceedings{MuellerBrinkmannPoddebniaketal.2019, author = {M{\"u}ller, Jens and Brinkmann, Marcus and Poddebniak, Damian and Schinzel, Sebastian and Schwenk, J{\"o}rg}, title = {What's up John­ny? - Co­vert Con­tent At­tacks on Email End-to-End En­cryp­ti­on}, series = {17th In­ter­na­tio­nal Con­fe­rence on Ap­p­lied Cryp­to­gra­phy and Net­work Se­cu­ri­ty (ACNS 2019)}, booktitle = {17th In­ter­na­tio­nal Con­fe­rence on Ap­p­lied Cryp­to­gra­phy and Net­work Se­cu­ri­ty (ACNS 2019)}, pages = {1 -- 18}, year = {2019}, abstract = {We show practical attacks against OpenPGP and S/MIMEencryption and digital signatures in the context of email. Instead of tar-geting the underlying cryptographic primitives, our attacks abuse legiti-mate features of the MIME standard and HTML, as supported by emailclients, to deceive the user regarding the actual message content. Wedemonstrate how the attacker can unknowingly abuse the user as a de-cryption oracle by replying to an unsuspicious looking email. Using thistechnique, the plaintext of hundreds of encrypted emails can be leakedat once. Furthermore, we show how users could be tricked into signingarbitrary text by replying to emails containing CSS conditional rules.An evaluation shows that "out of" OpenPGP-capable email clients,as well as "out of" clients supporting S/MIME, are vulnerable to atleast one attack. We provide different countermeasures and discuss theiradvantages and disadvantages.}, language = {de} } @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{MuellerBrinkmannPoddebniaketal.2020, author = {M{\"u}ller, Jens and Brinkmann, Marcus and Poddebniak, Damian and Schinzel, Sebastian and Schwenk, J{\"o}rg}, title = {Mailto: Me Your Secrets. On Bugs and Features in Email End-to-End Encryption}, series = {2020 IEEE Conference on Communications and Network Security (CNS)}, booktitle = {2020 IEEE Conference on Communications and Network Security (CNS)}, doi = {10.1109/CNS48642.2020.9162218}, pages = {1 -- 9}, year = {2020}, abstract = {OpenPGP and S/MIME are the two major standards for email end-to-end encryption. We show practical attacks against both encryption schemes in the context of email. First, we present a design flaw in the key update mechanism, allowing a third party to deploy a new key to the communication partners. Second, we show how email clients can be tricked into acting as an oracle for decryption or signing by exploiting their functionality to auto-save drafts. Third, we demonstrate how to exfiltrate the private key, based on proprietary mailto parameters implemented by various email clients. An evaluation shows that 8 out of 20 tested email clients are vulnerable to at least one attack. While our attacks do not target the underlying cryptographic primitives, they raise concerns about the practical security of OpenPGP and S/MIME email applications. Finally, we propose countermeasures and discuss their advantages and disadvantages.}, language = {de} } @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} } @inproceedings{PoddebniakIsingBoecketal.2021, author = {Poddebniak, Damian and Ising, Fabian and B{\"o}ck, Hanno and Schinzel, Sebastian}, title = {Why TLS is better without STARTTLS: A Security Analysis of STARTTLS in the Email Context}, series = {Proceedings of the 30th USENIX Security Symposium, August 11-13, 2021}, volume = {2021}, booktitle = {Proceedings of the 30th USENIX Security Symposium, August 11-13, 2021}, isbn = {978-1-939133-24-3}, year = {2021}, abstract = {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.}, language = {en} } @article{BrinkmannDresenMergetetal.2021, author = {Brinkmann, Marcus and Dresen, Christian and Merget, Robert and Poddebniak, Damian and M{\"u}ller, Jens and Somorovsky, Juraj and Schwenk, J{\"o}rg and Schinzel, Sebastian}, title = {ALPACA: Application Layer Protocol Confusion - Analyzing and Mitigating Cracks in TLS Authentication}, series = {30th USENIX Security Symposium}, journal = {30th USENIX Security Symposium}, year = {2021}, language = {en} } @inproceedings{WillingSaatjohannRathetal.2021, author = {Willing, Markus and Saatjohann, Christoph and Rath, Benjamin and Schinzel, Sebastian and Eckardt, Lars and K{\"o}be, Julia}, title = {Experiences with General Data Protection Regulations and Remote Monitoring of Implantable Rhythm Devices}, series = {87. Jahrestagung der Deutsche Gesellschaft f{\"u}r Kardiologie - Herz‑ und Kreislauforschung e.V}, booktitle = {87. Jahrestagung der Deutsche Gesellschaft f{\"u}r Kardiologie - Herz‑ und Kreislauforschung e.V}, publisher = {Springer-Verlag GmbH}, doi = {10.1007/s00392-021-01843-w}, year = {2021}, language = {en} } @article{WillingDresenGerlitzetal.2021, author = {Willing, Markus and Dresen, Christian and Gerlitz, Eva and Haering, Maximilian and Smith, Matthew and Binnewies, Carmen and Guess, Tim and Haverkamp, Uwe and Schinzel, Sebastian}, title = {Behavioral responses to a cyber attack in a hospital environment}, series = {Nature -- Scientific Reports}, journal = {Nature -- Scientific Reports}, doi = {10.1038/s41598-021-98576-7}, year = {2021}, abstract = {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.}, language = {en} } @inproceedings{SaatjohannIsingGierlingsetal.2022, author = {Saatjohann, Christoph and Ising, Fabian and Gierlings, Matthias and Noss, Dominik and Schimmler, Sascha and Klemm, Alexander and Grundmann, Leif and Frosch, Tilman and Schinzel, Sebastian}, title = {Sicherheit medizintechnischer Protokolle im Krankenhaus}, series = {SICHERHEIT 2022. Hrsg. Christian Wressnegger, Delphine Reinhardt, Thomas Barber, Bernhard C. Witt, Daniel Arp, Zoltan Mann}, booktitle = {SICHERHEIT 2022. Hrsg. Christian Wressnegger, Delphine Reinhardt, Thomas Barber, Bernhard C. Witt, Daniel Arp, Zoltan Mann}, publisher = {Gesellschaft f{\"u}r Informatik e.V.}, address = {Bonn}, isbn = {978-3-88579-717-3}, issn = {1617-5468}, doi = {10.18420/sicherheit2022_09}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-150072}, year = {2022}, abstract = {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 Angriffsoberfl{\"a}che. In diesem Beitrag analysieren wir die weit verbreiteten medizintechnischen Kommunikations-Protokolle DICOM und HL7 sowie Protokoll-Implementierungen auf ihre IT-Sicherheit. Daf{\"u}r pr{\"a}sentieren wir die Ergebnisse der Sicherheitsanalyse der DICOM- und HL7-Standards, einen Fuzzer "MedFUZZ" f{\"u}r diese Protokolle sowie einen Schwachstellenscanner "MedVAS", der Schwachstellen in medizintechnischen Produktivumgebungen auffinden kann.}, language = {de} } @inproceedings{MayerPoddebniakFischeretal.2022, author = {Mayer, Peter and Poddebniak, Damian and Fischer, Konstantin and Brinkmann, Marcus and Somorovsky, Juraj and Schinzel, Sebastian and Volkamer, Melanie}, title = {"I don't know why I check this...'' - Investigating Expert Users' Strategies to Detect Email Signature Spoofing Attacks}, series = {Eighteenth Symposium on Usable Privacy and Security (SOUPS 2022)}, booktitle = {Eighteenth Symposium on Usable Privacy and Security (SOUPS 2022)}, publisher = {USENIX Association}, address = {Boston, MA}, isbn = {978-1-939133-30-4}, pages = {77 -- 96}, year = {2022}, abstract = {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.}, language = {en} } @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{SaatjohannIsingSchinzel2024, author = {Saatjohann, Christoph and Ising, Fabian and Schinzel, Sebastian}, title = {KIM: Kaos In der Medizin}, series = {Sicherheit, Schutz und Zuverl{\"a}ssigkeit: Konferenzband der 12. Jahrestagung des Fachbereichs Sicherheit der Gesellschaft f{\"u}r Informatik e.V. (GI)}, booktitle = {Sicherheit, Schutz und Zuverl{\"a}ssigkeit: Konferenzband der 12. Jahrestagung des Fachbereichs Sicherheit der Gesellschaft f{\"u}r Informatik e.V. (GI)}, doi = {10.25974/fhms-17807}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-178072}, year = {2024}, abstract = {Die sichere E-Mail-Infrastruktur f{\"u}r {\"A}rzt*innen, Apotheker*innen, Krankenversicherungen und Kliniken in Deutschland, KIM - Kommunikation im Gesundheitswesen - ist mit {\"u}ber 200 Millionen E-Mails in den vergangenen zwei Jahren eine der am meisten genutzten Anwendungen in der Telematikinfrastruktur. Mit dem Ausgeben von S/MIME-Zertifikaten f{\"u}r alle medizinische Beteiligten in Deutschland verspricht KIM sichere Ende-zu-Ende-Verschl{\"u}sselung von E-Mails zwischen Heilberufler*innen in ganz Deutschland. In diesem Paper analysieren wir die KIM-Spezifikation sowie eine beispielhafte KIM-Installation in einer deutschen Zahnarztpraxis. Wir zeigen, dass KIM kryptografisch ein sehr hohes Sicherheitslevel erf{\"u}llt, doch in der Verarbeitung der E-Mails bei den Clients eine schwerwiegende Sicherheitsl{\"u}cke besteht. Weiterhin zeigen wir zwei Sicherheitsl{\"u}cken in dem KIM-Verarbeitungsmodul eines großen deutschen Unternehmens f{\"u}r medizinische Software. Diese Defizite zeigen außerdem M{\"a}ngel in dem verpflichtenden Zulassungsprozess der KIM-Komponenten auf.}, language = {de} }