Visible to the public Biblio

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Kellner, Ansgar, Horlboge, Micha, Rieck, Konrad, Wressnegger, Christian.  2019.  False Sense of Security: A Study on the Effectivity of Jailbreak Detection in Banking Apps. 2019 IEEE European Symposium on Security and Privacy (EuroS P). :1—14.
People increasingly rely on mobile devices for banking transactions or two-factor authentication (2FA) and thus trust in the security provided by the underlying operating system. Simultaneously, jailbreaks gain tremendous popularity among regular users for customizing their devices. In this paper, we show that both do not go well together: Jailbreaks remove vital security mechanisms, which are necessary to ensure a trusted environment that allows to protect sensitive data, such as login credentials and transaction numbers (TANs). We find that all but one banking app, available in the iOS App Store, can be fully compromised by trivial means without reverse-engineering, manipulating the app, or other sophisticated attacks. Even worse, 44% of the banking apps do not even try to detect jailbreaks, revealing the prevalent, errant trust in the operating system's security. This study assesses the current state of security of banking apps and pleads for more advanced defensive measures for protecting user data.
Biggio, Battista, Rieck, Konrad, Ariu, Davide, Wressnegger, Christian, Corona, Igino, Giacinto, Giorgio, Roli, Fabio.  2014.  Poisoning Behavioral Malware Clustering. Proceedings of the 2014 Workshop on Artificial Intelligent and Security Workshop. :27–36.
Clustering algorithms have become a popular tool in computer security to analyze the behavior of malware variants, identify novel malware families, and generate signatures for antivirus systems. However, the suitability of clustering algorithms for security-sensitive settings has been recently questioned by showing that they can be significantly compromised if an attacker can exercise some control over the input data. In this paper, we revisit this problem by focusing on behavioral malware clustering approaches, and investigate whether and to what extent an attacker may be able to subvert these approaches through a careful injection of samples with poisoning behavior. To this end, we present a case study on Malheur, an open-source tool for behavioral malware clustering. Our experiments not only demonstrate that this tool is vulnerable to poisoning attacks, but also that it can be significantly compromised even if the attacker can only inject a very small percentage of attacks into the input data. As a remedy, we discuss possible countermeasures and highlight the need for more secure clustering algorithms.
Wressnegger, Christian, Freeman, Kevin, Yamaguchi, Fabian, Rieck, Konrad.  2017.  Automatically Inferring Malware Signatures for Anti-Virus Assisted Attacks. Proceedings of the 2017 ACM on Asia Conference on Computer and Communications Security. :587–598.
Although anti-virus software has significantly evolved over the last decade, classic signature matching based on byte patterns is still a prevalent concept for identifying security threats. Anti-virus signatures are a simple and fast detection mechanism that can complement more sophisticated analysis strategies. However, if signatures are not designed with care, they can turn from a defensive mechanism into an instrument of attack. In this paper, we present a novel method for automatically deriving signatures from anti-virus software and discuss how the extracted signatures can be used to attack sensible data with the aid of the virus scanner itself. To this end, we study the practicability of our approach using four commercial products and exemplary demonstrate anti-virus assisted attacks in three different scenarios.
Gascon, Hugo, Grobauer, Bernd, Schreck, Thomas, Rist, Lukas, Arp, Daniel, Rieck, Konrad.  2017.  Mining Attributed Graphs for Threat Intelligence. Proceedings of the Seventh ACM on Conference on Data and Application Security and Privacy. :15–22.

Understanding and fending off attack campaigns against organizations, companies and individuals, has become a global struggle. As today's threat actors become more determined and organized, isolated efforts to detect and reveal threats are no longer effective. Although challenging, this situation can be significantly changed if information about security incidents is collected, shared and analyzed across organizations. To this end, different exchange data formats such as STIX, CyBOX, or IODEF have been recently proposed and numerous CERTs are adopting these threat intelligence standards to share tactical and technical threat insights. However, managing, analyzing and correlating the vast amount of data available from different sources to identify relevant attack patterns still remains an open problem. In this paper we present Mantis, a platform for threat intelligence that enables the unified analysis of different standards and the correlation of threat data trough a novel type-agnostic similarity algorithm based on attributed graphs. Its unified representation allows the security analyst to discover similar and related threats by linking patterns shared between seemingly unrelated attack campaigns through queries of different complexity. We evaluate the performance of Mantis as an information retrieval system for threat intelligence in different experiments. In an evaluation with over 14,000 CyBOX objects, the platform enables retrieving relevant threat reports with a mean average precision of 80%, given only a single object from an incident, such as a file or an HTTP request. We further illustrate the performance of this analysis in two case studies with the attack campaigns Stuxnet and Regin.

Goltzsche, David, Wulf, Colin, Muthukumaran, Divya, Rieck, Konrad, Pietzuch, Peter, Kapitza, Rüdiger.  2017.  TrustJS: Trusted Client-Side Execution of JavaScript. Proceedings of the 10th European Workshop on Systems Security. :7:1–7:6.

Client-side JavaScript has become ubiquitous in web applications to improve user experience and reduce server load. However, since clients are untrusted, servers cannot rely on the confidentiality or integrity of client-side JavaScript code and the data that it operates on. For example, client-side input validation must be repeated at server side, and confidential business logic cannot be offloaded. In this paper, we present TrustJS, a framework that enables trustworthy execution of security-sensitive JavaScript inside commodity browsers. TrustJS leverages trusted hardware support provided by Intel SGX to protect the client-side execution of JavaScript, enabling a flexible partitioning of web application code. We present the design of TrustJS and provide initial evaluation results, showing that trustworthy JavaScript offloading can further improve user experience and conserve more server resources.