@misc{DelaCadenaKaiserPanchenkoetal., author = {De la Cadena, Wladimir and Kaiser, Daniel and Panchenko, Andriy and Engel, Thomas}, title = {Out-of-the-box Multipath TCP as a Tor Transport Protocol: Performance and Privacy Implications}, series = {2020 IEEE 19th International Symposium on Network Computing and Applications (NCA), 24-27 Nov. 2020, Cambridge, MA, USA}, journal = {2020 IEEE 19th International Symposium on Network Computing and Applications (NCA), 24-27 Nov. 2020, Cambridge, MA, USA}, isbn = {978-1-7281-8326-8}, issn = {2643-7929}, doi = {10.1109/NCA51143.2020.9306702}, pages = {6}, language = {en} } @misc{MitsevaPennekampLohmoelleretal., author = {Mitseva, Asya and Pennekamp, Jan and Lohm{\"o}ller, Johannes and Ziemann, Torsten and Hoerchner, Carl and Wehrle, Klaus and Panchenko, Andriy}, title = {POSTER: How Dangerous is My Click? Boosting Website Fingerprinting By Considering Sequences of Webpages}, series = {Proceedings of the 28th ACM Conference on Computer and Communications Security (ACM CCS 2021), Seoul, Virtual Event, South Korea, November 2021}, journal = {Proceedings of the 28th ACM Conference on Computer and Communications Security (ACM CCS 2021), Seoul, Virtual Event, South Korea, November 2021}, publisher = {ACM Press}, address = {New York}, isbn = {978-1-4503-8454-4}, doi = {10.1145/3460120.3485347}, pages = {2411 -- 2413}, language = {en} } @misc{PanchenkoMitsevaKnabe, author = {Panchenko, Andriy and Mitseva, Asya and Knabe, Sara}, title = {WhisperChord: Scalable and Secure Node Discovery for Overlay Networks}, series = {IEEE 46th Conference on Local Computer Networks (LCN), Edmonton, AB, Canada , 4-7 Oct. 2021}, journal = {IEEE 46th Conference on Local Computer Networks (LCN), Edmonton, AB, Canada , 4-7 Oct. 2021}, publisher = {IEEE}, isbn = {978-1-6654-1886-7}, issn = {0742-1303}, doi = {10.1109/LCN52139.2021.9525008}, pages = {170 -- 177}, abstract = {Node discovery is a fundamental service for any overlay network, including anonymization networks. Although anonymization and node discovery are two disjoint services, the node discovery has a direct impact on the anonymization. Centralized methods require a trusted third party, limit the network scalability, and are vulnerable to intersection (statistical disclosure) attacks. Therefore, several distributed node discovery methods were proposed to meet the security requirements of anonymization networks through additional structures within Distributed Hash Tables (DHTs). However, they require a high management overhead, a strict cooperation between nodes, and are susceptible to active and passive attacks.We propose WhisperChord—an alternative distributed node discovery approach, which incorporates gossiping into structured overlays. WhisperChord is based on a Chord DHT and neither creates any additional structures within the DHT nor requires any trusted third party. Via simulations, we show that our method provides superior protection against active attacks than prior methods and can effectively thwart information leakages.}, language = {en} } @misc{PanchenkoMitsevaZiemannetal., author = {Panchenko, Andriy and Mitseva, Asya and Ziemann, Torsten and Hering, Till}, title = {GuardedGossip: Secure and Anonymous Node Discovery in Untrustworthy Networks}, series = {Security and Privacy in Communication Networks : 17th EAI International Conference, SecureComm 2021, Virtual Event, September 6-9, 2021, Proceedings, Part I}, journal = {Security and Privacy in Communication Networks : 17th EAI International Conference, SecureComm 2021, Virtual Event, September 6-9, 2021, Proceedings, Part I}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-90018-2}, issn = {1867-8211}, doi = {10.1007/978-3-030-90019-9_7}, pages = {123 -- 143}, abstract = {Node discovery is a fundamental service for any overlay network. It is a particular challenge to provide unbiased discovery in untrustworthy environments, e.g., anonymization networks. Although a major line of research focused on solving this problem, proposed methods have been shown to be vulnerable either to active attacks or to leak routing information, both threatening the anonymity of users. In response, we propose GuardedGossip—a novel gossip-based node discovery protocol—that achieves an unbiased random node discovery in a fully-decentralized and highly-scalable fashion. It is built on top of a Chord distributed hash table (DHT) and relies on witness nodes and bound checks to resist active attacks. To limit routing information leakages, GuardedGossip uses gossiping to create uncertainty in the process of node discovery. By incorporating the principles of DHTs with the unstructured nature of gossiping in a subtle way, we profit from the strengths of both techniques while carefully mitigating their shortcomings. We show that GuardedGossip provides a sufficient level of security for users even if 20\% of the participating nodes are malicious. Concurrently, our system scales gracefully and provides an adequate overhead for its security and privacy benefits.}, language = {en} } @misc{PennekampHenzeZinnenetal., author = {Pennekamp, Jan and Henze, Martin and Zinnen, Andreas and Lanze, Fabian and Wehrle, Klaus and Panchenko, Andriy}, title = {CUMUL \& Co: High-Impact Artifacts for Website Fingerprinting Research}, series = {38th Annual Computer Security Applications Conference (ACSAC 2022), Austin, Texas, USA, December 5-9, 2022.}, journal = {38th Annual Computer Security Applications Conference (ACSAC 2022), Austin, Texas, USA, December 5-9, 2022.}, pages = {6}, abstract = {Anonymous communication on the Internet is about hiding the relationship between communicating parties. At NDSS '16, we presented a new website fingerprinting approach, CUMUL, that utilizes novel features and a simple yet powerful algorithm to attack anonymization networks such as Tor. Based on pattern observation of data flows, this attack aims at identifying the content of encrypted and anonymized connections. Apart from the feature generation and the used classifier, we also provided a large dataset to the research community to study the attack at Internet scale. In this paper, we emphasize the impact of our artifacts by analyzing publications referring to our work with respect to the dataset, feature extraction method, and source code of the implementation. Based on this data, we draw conclusions about the impact of our artifacts on the research field and discuss their influence on related cybersecurity topics. Overall, from 393 unique citations, we discover more than 130 academic references that utilize our artifacts, 61 among them are highly influential (according to SemanticScholar), and at least 43 are from top-ranked security venues. This data underlines the significant relevance and impact of our work as well as of our artifacts in the community and beyond.}, language = {en} } @misc{ReuterHillerPennekampetal., author = {Reuter, Sebastian and Hiller, Jens and Pennekamp, Jan and Panchenko, Andriy and Wehrle, Klaus}, title = {Demo: Traffic Splitting for Tor - A Defense against Fingerprinting Attacks}, series = {Conference on Networked Systems 2021 (NetSys 2021)}, journal = {Conference on Networked Systems 2021 (NetSys 2021)}, issn = {1863-2122}, doi = {10.14279/tuj.eceasst.80.1151.1128}, pages = {4}, abstract = {Website fingerprinting (WFP) attacks on the anonymity network Tor have become ever more effective. Furthermore, research discovered that proposed defenses are insufficient or cause high overhead. In previous work, we presented a new WFP defense for Tor that incorporates multipath transmissions to repel malicious Tor nodes from conducting WFP attacks. In this demo, we showcase the operation of our traffic splitting defense by visually illustrating the underlying Tor multipath transmission using LED-equipped Raspberry Pis.}, language = {en} } @misc{MitsevaPanchenko, author = {Mitseva, Asya and Panchenko, Andriy}, title = {Stop, don't click here anymore: boosting website fingerprinting by considering sets of subpages}, series = {Proceedings of the 33rd USENIX Security Symposium (USENIX Sec 2024), Philadelphia, PA, USA, August 14-16, 2024}, journal = {Proceedings of the 33rd USENIX Security Symposium (USENIX Sec 2024), Philadelphia, PA, USA, August 14-16, 2024}, isbn = {978-1-939133-44-1}, pages = {4139 -- 4156}, abstract = {A type of traffic analysis, website fingerprinting (WFP), aims to reveal the website a user visits over an encrypted and anonymized connection by observing and analyzing data flow patterns. Its efficiency against anonymization networks such as Tor has been widely studied, resulting in methods that have steadily increased in both complexity and power. While modern WFP attacks have proven to be highly accurate in laboratory settings, their real-world feasibility is highly debated. These attacks also exclude valuable information by ignoring typical user browsing behavior: users often visit multiple pages of a single website sequentially, e.g., by following links. In this paper, we aim to provide a more realistic assessment of the degree to which Tor users are exposed to WFP. We propose both a novel WFP attack and efficient strategies for adapting existing methods to account for sequential visits of pages within a website. While existing WFP attacks fail to detect almost any website in real-world settings, our novel methods achieve F1-scores of 1.0 for more than half of the target websites. Our attacks remain robust against state-of- the-art WFP defenses, achieving 2.5 to 5 times the accuracy of prior work, and in some cases even rendering the defenses useless. Our methods enable to estimate and to communicate to the user the risk of successive page visits within a website (even in the presence of noise pages) to stop before the WFP attack reaches a critical level of confidence.}, language = {en} } @misc{MorenoPastranaReelfsetal., author = {Moreno, Jos{\´e} Miguel and Pastrana, Sergio and Reelfs, Jens Helge and Vallina, Pelayo and Panchenko, Andriy and Smaragdakis, Georgios and Hohlfeld, Oliver and Vallina-Rodriguez, Narseo and Tapiador, Juan}, title = {Reviewing War: Unconventional User Reviews as a Side Channel to Circumvent Information Controls}, doi = {10.48550/arXiv.2302.00598}, pages = {11}, abstract = {During the first days of the 2022 Russian invasion of Ukraine, Russia's media regulator blocked access to many global social media platforms and news sites, including Twitter, Facebook, and the BBC. To bypass the information controls set by Russian authorities, pro-Ukrainian groups explored unconventional ways to reach out to the Russian population, such as posting war-related content in the user reviews of Russian business available on Google Maps or Tripadvisor. This paper provides a first analysis of this new phenomenon by analyzing the creative strategies to avoid state censorship. Specifically, we analyze reviews posted on these platforms from the beginning of the conflict to September 2022. We measure the channeling of war messages through user reviews in Tripadvisor and Google Maps, as well as in VK, a popular Russian social network. Our analysis of the content posted on these services reveals that users leveraged these platforms to seek and exchange humanitarian and travel advice, but also to disseminate disinformation and polarized messages. Finally, we analyze the response of platforms in terms of content moderation and their impact.}, language = {en} } @misc{BuscemiTurcanuCastignanietal., author = {Buscemi, Alessio and Turcanu, Ion and Castignani, German and Panchenko, Andriy and Engel, Thomas and Shin, Kang G.}, title = {A Survey on Controller Area Network Reverse Engineering}, series = {IEEE Communications Surveys \& Tutorials}, volume = {25}, journal = {IEEE Communications Surveys \& Tutorials}, number = {3,3}, publisher = {IEEE}, issn = {1553-877X}, doi = {10.1109/COMST.2023.3264928}, pages = {1445 -- 1481}, abstract = {Controller Area Network (CAN) is a masterless serial bus designed and widely used for the exchange of mission and time-critical information within commercial vehicles. In-vehicle communication is based on messages sent and received by Electronic Control Units (ECUs) connected to this serial bus network. Although unencrypted, CAN messages are not easy to interpret. In fact, Original Equipment Manufacturers (OEMs) attempt to achieve security through obscurity by encoding the data in their proprietary format, which is kept secret from the general public. As a result, the only way to obtain clear data is to reverse engineer CAN messages. Driven by the need for in-vehicle message interpretation, which is highly valuable in the automotive industry, researchers and companies have been working to make this process automated, fast, and standardized. In this paper, we provide a comprehensive review of the state of the art and summarize the major advances in CAN bus reverse engineering. We are the first to provide a taxonomy of CAN tokenization and translation techniques. Based on the reviewed literature, we highlight an important issue: the lack of a public and standardized dataset for the quantitative evaluation of translation algorithms. In response, we define a complete set of requirements for standardizing the data collection process. We also investigate the risks associated with the automation of CAN reverse engineering, in particular with respect to the security network and the safety and privacy of drivers and passengers. Finally, we discuss future research directions in CAN reverse engineering.}, language = {en} } @misc{MitsevaAlexandrovaPanchenko, author = {Mitseva, Asya and Alexandrova, Marharyta and Panchenko, Andriy}, title = {Security and Performance Implications of BGP Rerouting-resistant Guard Selection Algorithms for Tor}, series = {Computers and Security}, volume = {132}, journal = {Computers and Security}, issn = {1872-6208}, doi = {10.1016/j.cose.2023.103374}, abstract = {Tor is the most popular anonymization network with millions of daily users. This makes it an attractive target for attacks, e.g., by malicious autonomous systems (ASs) performing active routing attacks to become man in the middle and deanonymize users. It was shown that the number of such malicious ASs is significantly larger than previously expected due to the lack of security guarantees in the Border Gateway Protocol (BGP). In response, recent works suggest alternative Tor path selection methods preferring Tor nodes with higher resilience to active BGP attacks. In this work, we analyze the implications of such proposals and demonstrate that two state-of-the-art path selection methods, namely Counter-RAPTOR and DPSelect, are not as secure as thought before. First, we show that DPSelect achieves only one third of its originally claimed resilience and, thus, is not as resilient as widely accepted. Second, we reveal that the resilience to active BGP attacks on the way back, i.e., from the first anonymization node to a given Tor user, provided by both methods is significantly lower than on the forward path. Beside their lower resilience in specific cases, we show that for particular users the usage of Counter-RAPTOR and DPSelect also leads to leakage of user's location. Furthermore, we uncover the performance implications of both methods and identify scenarios where their usage leads to significant performance bottlenecks. Finally, we propose a new metric to quantify the user's location leakage by path selection. Using this metric and performing large-scale analysis, we show to which extent a malicious Tor middle node can fingerprint the user's location and the confidence it can achieve. Our findings shed light on the implications of path selection methods on the users' anonymity and the need for further research.}, language = {en} }