@inproceedings{PanchenkoLanzeZinnenetal., author = {Panchenko, Andriy and Lanze, Fabian and Zinnen, Andreas and Henze, Martin and Pennekamp, Jan and Engel, Thomas and Wehrle, Klaus}, title = {Website Fingerprinting at Internet Scale}, series = {Proceedings of the 23rd Internet Society (ISOC) Network and Distributed System Security Symposium (NDSS 2016), San Diego, USA, February 2016}, booktitle = {Proceedings of the 23rd Internet Society (ISOC) Network and Distributed System Security Symposium (NDSS 2016), San Diego, USA, February 2016}, publisher = {Internet Society}, address = {Reston, VA}, isbn = {1-891562-41-X}, pages = {15}, language = {en} } @misc{MitsevaPanchenkoLanzeetal., author = {Mitseva, Asya and Panchenko, Andriy and Lanze, Fabian and Henze, Martin and Engel, Thomas and Wehrle, Klaus}, title = {POSTER: Fingerprinting Tor Hidden Services}, series = {In Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security (CCS '16). Association for Computing Machinery, New York, NY, USA}, journal = {In Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security (CCS '16). Association for Computing Machinery, New York, NY, USA}, publisher = {ACM}, address = {New York}, isbn = {978-1-4503-4139-4}, doi = {10.1145/2976749.2989054}, pages = {1766 -- 1768}, language = {en} } @inproceedings{PanchenkoMitsevaHenzeetal., author = {Panchenko, Andriy and Mitseva, Asya and Henze, Martin and Lanze, Fabian and Engel, Thomas and Wehrle, Klaus}, title = {Analysis of Fingerprinting Techniques for Tor Hidden Services}, series = {WPES '17 Proceedings of the 2017 on Workshop on Privacy in the Electronic Society, Dallas, Texas, USA, October 2017}, booktitle = {WPES '17 Proceedings of the 2017 on Workshop on Privacy in the Electronic Society, Dallas, Texas, USA, October 2017}, publisher = {ACM}, address = {New York, NY}, isbn = {978-1-4503-5175-1}, doi = {10.1145/3139550.3139564}, pages = {165 -- 175}, language = {en} } @misc{HohlfeldKrudeReelfsetal., author = {Hohlfeld, Oliver and Krude, Johannes and Reelfs, Jens Helge and R{\"u}th, Jan and Wehrle, Klaus}, title = {Demystifying the Performance of XDP BPF}, series = {IEEE Conference on Network Softwarization, 24-28 June 2019, Paris, France}, journal = {IEEE Conference on Network Softwarization, 24-28 June 2019, Paris, France}, doi = {10.1109/NETSOFT.2019.8806651}, pages = {5}, abstract = {High packet rates at ≥ 10 GBit/s challenge the packet processing performance of network stacks. A common solution is to offload (parts of) the user-space packet processing to other execution environments, e.g., into the device driver (kernel-space), the NIC or even from virtual machines into the host operating system (OS), or any combination of those. While common wisdom states that offloading optimizes performance, neither benefits nor negative effects are comprehensively studied. In this paper, we aim to shed light on the benefits and shortcomings of eBPF/XDP-based offloading from the user-space to i) the kernel-space or ii) a smart NIC-including VM virtualization. We show that offloading can indeed optimize packet processing, but only if the task is small and optimized for the target environment. Otherwise, offloading can even lead to detrimental performance.}, language = {en} } @misc{PennekampHillerReuteretal., author = {Pennekamp, Jan and Hiller, Jens and Reuter, Sebastian and De la Cadena, Wladimir and Mitseva, Asya and Henze, Martin and Engel, Thomas and Wehrle, Klaus and Panchenko, Andriy}, title = {Multipathing Traffic to Reduce Entry Node Exposure in Onion Routing}, series = {Proceedings of the 27th annual IEEE International Conference on Network Protocols (Poster) (IEEE ICNP 2019), Chicago, Illinois, USA, October 2019}, journal = {Proceedings of the 27th annual IEEE International Conference on Network Protocols (Poster) (IEEE ICNP 2019), Chicago, Illinois, USA, October 2019}, publisher = {IEEE Press}, isbn = {978-1-7281-2700-2}, issn = {2643-3303}, doi = {10.1109/ICNP.2019.8888029}, pages = {2}, abstract = {Users of an onion routing network, such as Tor, depend on its anonymity properties. However, especially malicious entry nodes, which know the client's identity, can also observe the whole communication on their link to the client and, thus, conduct several de-anonymization attacks. To limit this exposure and to impede corresponding attacks, we propose to multipath traffic between the client and the middle node to reduce the information an attacker can obtain at a single vantage point. To facilitate the deployment, only clients and selected middle nodes need to implement our approach, which works transparently for the remaining legacy nodes. Furthermore, we let clients control the splitting strategy to prevent any external manipulation.}, language = {en} } @misc{HillerPennekampDahlmannsetal., author = {Hiller, Jens and Pennekamp, Jan and Dahlmanns, Markus and Henze, Martin and Panchenko, Andriy and Wehrle, Klaus}, title = {Tailoring Onion Routing to the Internet of Things: Security and Privacy in Untrusted Environments}, series = {Proceedings of the 27th annual IEEE International Conference on Network Protocols (IEEE ICNP 2019), Chicago, Illinois, USA, October 2019}, journal = {Proceedings of the 27th annual IEEE International Conference on Network Protocols (IEEE ICNP 2019), Chicago, Illinois, USA, October 2019}, publisher = {IEEE Press}, isbn = {978-1-7281-2700-2}, issn = {2643-3303}, doi = {10.1109/ICNP.2019.8888033}, pages = {12}, abstract = {An increasing number of IoT scenarios involve mobile, resource-constrained IoT devices that rely on untrusted networks for Internet connectivity. In such environments, attackers can derive sensitive private information of IoT device owners, e.g., daily routines or secret supply chain procedures, when sniffing on IoT communication and linking IoT devices and owner. Furthermore, untrusted networks do not provide IoT devices with any protection against attacks from the Internet. Anonymous communication using onion routing provides a well-proven mechanism to keep the relationship between communication partners secret and (optionally) protect against network attacks. However, the application of onion routing is challenged by protocol incompatibilities and demanding cryptographic processing on constrained IoT devices, rendering its use infeasible. To close this gap, we tailor onion routing to the IoT by bridging protocol incompatibilities and offloading expensive cryptographic processing to a router or web server of the IoT device owner. Thus, we realize resource-conserving access control and end-toend security for IoT devices. To prove applicability, we deploy onion routing for the IoT within the well-established Tor network enabling IoT devices to leverage its resources to achieve the same grade of anonymity as readily available to traditional devices.}, language = {en} } @misc{DeLaCadenaMitsevaPennekampetal., author = {De La Cadena, Wladimir and Mitseva, Asya and Pennekamp, Jan and Hiller, Jens and Lanze, Fabian and Engel, Thomas and Wehrle, Klaus and Panchenko, Andriy}, title = {POSTER: Traffic Splitting to Counter Website Fingerprinting}, series = {CCS '19 Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security , London, UK, November 11 - 15, 2019.}, journal = {CCS '19 Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security , London, UK, November 11 - 15, 2019.}, publisher = {ACM Press}, address = {New York}, isbn = {978-1-4503-6747-9}, doi = {10.1145/3319535.3363249}, pages = {2533 -- 2535}, abstract = {Website fingerprinting (WFP) is a special type of traffic analysis, which aims to infer the websites visited by a user. Recent studies have shown that WFP targeting Tor users is notably more effective than previously expected. Concurrently, state-of-the-art defenses have been proven to be less effective. In response, we present a novel WFP defense that splits traffic over multiple entry nodes to limit the data a single malicious entry can use. Here, we explore several traffic-splitting strategies to distribute user traffic. We establish that our weighted random strategy dramatically reduces the accuracy from nearly 95\% to less than 35\% for four state-of-the-art WFP attacks without adding any artificial delays or dummy traffic.}, language = {en} } @misc{SanderRuethHohlfeldetal., author = {Sander, Constantin and R{\"u}th, Jan and Hohlfeld, Oliver and Wehrle, Klaus}, title = {DeePCCI: Deep Learning-based Passive Congestion Control Identification}, series = {In Proceedings of the ACM SIGCOMM Workshop on Network Meets AI \& ML (NetAI '19), August 19-24, 2019, Beijing, China}, journal = {In Proceedings of the ACM SIGCOMM Workshop on Network Meets AI \& ML (NetAI '19), August 19-24, 2019, Beijing, China}, publisher = {ACM}, address = {New York}, isbn = {978-1-4503-6872-8}, doi = {10.1145/3341216.3342211}, pages = {37 -- 43}, language = {en} } @misc{WolsingRuethWehrleetal., author = {Wolsing, Konrad and R{\"u}th, Jan and Wehrle, Klaus and Hohlfeld, Oliver}, title = {A Performance Perspective on Web Optimized Protocol Stacks: TCP+TLS+HTTP/2 vs. QUIC}, series = {Proceedings of the Applied Networking Research Workshop (ANRW '19), July 22, 2019, Montreal, QC, Canada}, journal = {Proceedings of the Applied Networking Research Workshop (ANRW '19), July 22, 2019, Montreal, QC, Canada}, publisher = {ACM}, address = {New York}, isbn = {978-1-4503-6848-3}, doi = {10.1145/3340301.3341123}, pages = {1 -- 7}, language = {en} } @misc{RuethWolsingWehrleetal., author = {R{\"u}th, Jan and Wolsing, Konrad and Wehrle, Klaus and Hohlfeld, Oliver}, title = {Perceiving QUIC: Do Users Notice or Even Care?}, series = {CoNEXT '19: International Conference On Emerging Networking Experiments And Technologies, December 9-12, 2019, Orlando, FL, USA. ACM, New York, NY, USA}, journal = {CoNEXT '19: International Conference On Emerging Networking Experiments And Technologies, December 9-12, 2019, Orlando, FL, USA. ACM, New York, NY, USA}, publisher = {ACM}, address = {New York, NY, USA}, doi = {10.1145/3359989.3365416}, pages = {7}, language = {en} } @misc{DelaCadenaMitsevaHilleretal., author = {De la Cadena, Wladimir and Mitseva, Asya and Hiller, Jens and Pennekamp, Jan and Reuter, Sebastian and Filter, Julian and Engel, Thomas and Wehrle, Klaus and Panchenko, Andriy}, title = {TrafficSliver: Fighting Website Fingerprinting Attacks with Traffic Splitting}, series = {CCS '20: Proceedings of the 2020 ACM SIGSAC Conference on Computer and Communications Security, October 2020}, journal = {CCS '20: Proceedings of the 2020 ACM SIGSAC Conference on Computer and Communications Security, October 2020}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-7089-9}, doi = {10.1145/3372297.3423351}, pages = {1971 -- 1985}, abstract = {Website fingerprinting (WFP) aims to infer information about the content of encrypted and anonymized connections by observing patterns of data flows based on the size and direction of packets. By collecting traffic traces at a malicious Tor entry node — one of the weakest adversaries in the attacker model of Tor — a passive eavesdropper can leverage the captured meta-data to reveal the websites visited by a Tor user. As recently shown, WFP is significantly more effective and realistic than assumed. Concurrently, former WFP defenses are either infeasible for deployment in real-world settings or defend against specific WFP attacks only. To limit the exposure of Tor users to WFP, we propose novel lightweight WFP defenses, TrafficSliver, which successfully counter today's WFP classifiers with reasonable bandwidth and latency overheads and, thus, make them attractive candidates for adoption in Tor. Through user-controlled splitting of traffic over multiple Tor entry nodes, TrafficSliver limits the data a single entry node can observe and distorts repeatable traffic patterns exploited by WFP attacks.We first propose a network-layer defense, in which we apply the concept of multipathing entirely within the Tor network. We show that our network-layer defense reduces the accuracy from more than 98\% to less than 16\% for all state-of-the-art WFP attacks without adding any artificial delays or dummy traffic. We further suggest an elegant client-side application-layer defense, which is independent of the underlying anonymization network. By sending single HTTP requests for different web objects over distinct Tor entry nodes, our application-layer defense reduces the detection rate of WFP classifiers by almost 50 percentage points. Although it offers lower protection than our network-layer defense, it provides a security boost at the cost of a very low implementation overhead and is fully compatible with today's Tor network.}, language = {en} } @misc{HillerHenzeZimmermannetal., author = {Hiller, Jens and Henze, Martin and Zimmermann, Torsten and Hohlfeld, Oliver and Wehrle, Klaus}, title = {The Case for Session Sharing: Relieving Clients from TLS Handshake Overheads}, series = {2019 IEEE 44th LCN Symposium on Emerging Topics in Networking (LCN Symposium), 14-17 Oct. 2019, Osnabr{\"u}ck, Germany}, journal = {2019 IEEE 44th LCN Symposium on Emerging Topics in Networking (LCN Symposium), 14-17 Oct. 2019, Osnabr{\"u}ck, Germany}, publisher = {IEEE}, isbn = {978-1-7281-2561-9}, doi = {10.1109/LCNSymposium47956.2019.9000667}, pages = {9}, abstract = {In recent years, the amount of traffic protected with Transport Layer Security (TLS) has significantly increased and new protocols such as HTTP/2 and QUIC further foster this emerging trend. However, protecting traffic with TLS has significant impacts on network entities. While the restrictions for middleboxes have been extensively studied, addressing the impact of TLS on clients and servers has been mostly neglected so far. Especially mobile clients in emerging 5G and IoT deployments suffer from significantly increased latency, traffic, and energy overheads when protecting traffic with TLS. In this paper, we address this emerging topic by thoroughly analyzing the impact of TLS on clients and servers and derive opportunities for significantly decreasing latency of TLS communication and downsizing TLS management traffic, thereby also reducing TLSinduced server load. We propose a protocol compatible redesign of TLS session management to use these opportunities and showcase their potential based on mobile device traffic and mobile web-browsing traces. These show promising potentials for latency improvements by up to 25.8\% and energy savings of up to 26.3\%.}, 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{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} }