Figure 5 - uploaded by George Danezis
Content may be subject to copyright.
Source publication
We consider the e ect attackers who disrupt anonymous communications have on the security of traditional high-and low-latency anonymous communication systems, as well as on the Hydra-Onion and Cashmere systems that aim to o er reliable mixing, and Salsa, a peer-to-peer anonymous com-munication network. We show that denial of service (DoS) lowers an...
Context in source publication
Similar publications
Smart grid networks offer two-way communication between the smart meters and the utility service providers (USPs). This enables the USPs to analyze real-time data emanating from the consumers and offer dynamic adjustments to the power generation and transmission. However, the periodical transmission of consumption reports from the smart meters towa...
Since the turn of the century, the public have lost trust and confidence in the accounting profession, likely due to high profile accounting scandals and the financial crisis, and the on-going tax avoidance issue. This has inspired ICAS to conduct a comprehensive review of the current fundamental principles of ethics from the IESBA Code of Ethics f...
In this digital era, two entities can exchange the messages over internet even through the physical distance between them is much far. Before exchange they require to authenticate each other via authentication scheme. Biometric is one of the unique feature for each entity and can be accustomed to identify the authenticity of the entity. Motivated b...
We consider the eect attackers who disrupt anonymous communications have on the security of traditional high- and low-latency anonymous communication systems, as well as on the Hydra-Onion and Cashmere systems that aim to oer reliable mixing, and Salsa, a peer-to-peer anonymous com- munication network. We show that denial of service (DoS) lowers an...
A novel client puzzle protocol, the memoryless puzzle protocol (MPP), is proposed and investigated. The goal is to show that MPP is a viable solution for mitigating distributed denial-of-service (DDoS) attacks in an anonymous routing environment. One such environment, Tor, provides anonymity for interactive Internet services. However, Tor relies on...
Citations
... While these tools serve an important role, and help obfuscate the identity of the user, they can be insufficient against determined adversaries capable of observing large swaths of traffic (e.g., malicious ISPs). Such adversaries (e.g., ISPs or nation states) can easily identify users and the traffic content through metadata such as packet timing, packet size, and other identifying features-even when all traffic is encrypted [9,13,37,45,49,58,77,82,84,96]. State-ofthe-art attacks can deanonymize encrypted Tor traffic with upwards of 90% accuracy by analyzing the encrypted packet traffic [9,45,82]. ...
... We evaluate anonymity in mixnets using two metrics: (i) fraction of fully compromised routes [1,5], and (ii) entropy [24,48]. The metrics express different aspects of anonymity, with the first focusing on worst-case scenarios and the second on average-case scenarios. ...
... We consider a mixnet that routes λ U = 5000 messages per second and that has a width of W = 10 mixes per layer, meaning that each mix routes on average 500 messages per second. 5 We consider that the average end-to-end latency D e2e is fixed per optimization experiment and evaluate anonymity for a range of possible D e2e values, from 0.25 to 5 seconds. We first consider a global network adversary that can observe all links but does not control any mix nodes, i.e., B = b = 0. Next, we consider an adversary that, in addition to globally observing the network, also controls b = 10% of nodes in the mixnet. ...
... In the case of adversaries that do not control any nodes in the mixnet (B = 0), the fraction of fully compromised routes α F is zero for any number of mixnet layers L ≥ 1. Worst-case anonymity constraints are therefore satisfied for all possible values of β. 5 The currently available Nym implementation is benchmarked at 3125 Sphinx packet decryptions per second per processing core. An average node load of 500 messages per second enables mix nodes to tolerate traffic peaks of up to 6x the average load. ...
We propose a method to optimally select mix network parameters for a given deployment context and adversarial model. Our method considers both worstcase and average-case anonymity and selects configurations that meet worst-case constraints while maximizing average anonymity. We apply our methods to mixnet size optimization to determine the number and width of mixnet layers, and provide results for various deployment and adversarial scenarios. For cases where the deployment context suddenly changes (drop in user traffic) we evaluate countermeasures based on mix-generated dummy traffic and show that inexpensive link dummies can significantly boost protection in some of these cases.
... The security of many known designs, such as Vu-vuzela [67], Karaoke [37], Loopix [49], and Nym [16] rely on the anytrust assumption where at least one server in the user's path must be honest. In most Mixnet literature, the security analysis often considers active attacks like traffic analysis attack [1], (n-1) attack [57], and Denial-of-Service (DoS) attack [4]. However, taken for granted are practical deployment issues such as network configuration and routing, network churn, and risk for real-world usage patterns. ...
Mixnets are a fundamental type of anonymous communication system and recent academic research has made progress in designing Mixnets that are scalable, have sustainable communication/computation overhead, and/or provable security. We focus our work on stratified Mixnets, a popular design with real-world adoption. The security of many designs rely on the anytrust assumption where at least one server in the user's path must be honest. We identify the critical role Mixnet topological configuration algorithms play for user anonymity, and propose Bow-Tie, a performant topological engineering design for Mixnets that further ensures the anytrust assumption holds realized by introducing guard mixes. To draw actionable conclusions, we perform an analysis of the best realistic and resource-bounded adversarial strategies against each of the studied algorithms, and evaluate security metrics against each best adversarial strategy. Moreover, we highlight the need for a temporal security analysis and develop routesim, a simulator to evaluate the effect of temporal dynamics and user behaviors over the Mixnet. The resulting security notions are complementary to the state-of-the-art entropic definitions. The simulator is designed to help Mixnets developers in assessing the devil in the details resulting from design decisions. Ultimately, our results suggest strong potential improvements to current designs and guidance for shaping Mix networks.
... Attacks that discover the guard of a Tor user (victim) are thus an important subject of research. Identifying a victim's guard may help expose the victim's identity or enable other attacks, including user geolocation [18], traffic confirmation [25,36], website fingerprinting [37,44,57,58], and selective denial-ofservice attacks to force the victim to choose a malicious guard [7,13,21,23]. Depending on bilateral agreements and the guard's jurisdiction, an adversary may seize [56] or subpoena [6,11] the guard or its network provider to access traffic logs. Adversaries with offensive capabilities may try to compromise the guard server. ...
... Attack Impact and Feasibility. Typically, guard discovery serves as a stepping stone for further attacks such as traffic confirmation [25], website fingerprinting [37,57], and selective denial of service [7]. Upon identifying a victim's guard, actors with offensive capabilities may go on to compromise, coerce, or subpoena the server. ...
We present a novel web-based attack that identifies a Tor user’s guard in a matter of seconds. Our attack is low-cost, fast, and stealthy. It requires only a moderate amount of resources and can be deployed by website owners, third-party script providers, and malicious exits—if the website traffic is unencrypted. The attack works by injecting resources from non-existing onion service addresses into a webpage. Upon visiting the attack webpage with Tor Browser, the victim’s Tor client creates many circuits to look up the non-existing addresses. This allows middle relays controlled by the adversary to detect the distinctive traffic pattern of the “404 Not Found” lookups and identify the victim’s guard. We evaluate our attack with extensive simulations and live Tor network measurements, taking a range of victim machine, network, and geolocation configurations into account. We find that an adversary running a small number of HSDirs and providing 5 % of Tor’s relay bandwidth needs 12.06 seconds to identify the guards of 50 % of the victims, while it takes 22.01 seconds to discover 90 % of the victims’ guards. Finally, we evaluate a set of countermeasures against our attack including a defense that we develop based on a token bucket and the recently proposed Vanguards-lite defense in Tor.
... Attacks like load module, command injections, eject attacks, and many more. And extensive usage of internet bandwidth known as DoS [19] attack, for example, Smurf, TearDrop, etc. Total 24 types of attacks are present in those four categories. ...
Going digital involves networking with so many connected devices, so network security becomes a critical task for everyone. But an intrusion detection system can help us to detect malicious activity in a system or network. But generally, intrusion detection systems (IDS) are not reliable and sustainable also they required more resources. So recent years so many machine learning methods are proposed to give higher accuracy with minimal false alerts. But analyzing those huge traffic data is still challenging. So in this article, we proposed a technique using the Support Vector Machine & Naive Bayes algorithm, by using this we can solve the classification problem of the intrusion detection system. For evaluating our proposed method we use NSL-KDD and UNSW-NB15 dataset. And after getting the result we see that the SVM works better than the Naive Bayes algorithm on that dataset.
... Due to its popularity and transparent development processes [61], many researchers have explored attacks that can de-anonymize Tor users and hidden-service providers by monitoring the network traffic. Recent attack vectors for Tor include BGP-based attacks [62], [63], website fingerprinting [64], [65], [66], [67], traffic correlation [36], [37], [68], [69], congestion attack [70], [71] and targeted DoS [38], [72]. Meanwhile, researchers also propose methods to enhance Tor's security by optimizing the bandwidth report for selecting guard nodes [73] and monitoring circuit construction [74]. ...
Traditional anonymous networks (e.g., Tor) are vulnerable to traffic analysis attacks that monitor the whole network traffic to determine which users are communicating. To preserve user anonymity against traffic analysis attacks, the emerging mix networks mess up the order of packets through a set of centralized and explicit shuffling nodes. However, this centralized design of mix networks is insecure against targeted DoS attacks that can completely block these shuffling nodes. In this paper, we present DAENet, an efficient mix network that resists both targeted DoS attacks and traffic analysis attacks with a new abstraction called Stealthy Peer-to-Peer (P2P) Network. The stealthy P2P network effectively hides the shuffling nodes used in a routing path into the whole network, such that adversaries cannot distinguish specific shuffling nodes and conduct targeted DoS attacks to block these nodes. In addition, to handle traffic analysis attacks, we leverage the confidentiality and integrity protection of Intel SGX to ensure trustworthy packet shuffles at each distributed host, and use multiple routing paths to prevent adversaries from tracking and revealing user identities. We show that our system is scalable with moderate latency (2.2s) when running in a cluster of 10,000 participants and is robust in the case of machine failures, making it an attractive new design for decentralized anonymous communication. DAENet's code is released on http://github.com/tdsc0652/dae-net.
... If messagging over the ACN is not completely prevented, the attack still has an impact. Dropped messages lead to degraded anonymity when using a mix network since retransmissions increase the potential of statistical disclosure as shown in [BDMT07]. 3 ...
... Following the publication of this work in USENIX Security '17, PANORAMIX adopted Loopix as its core infrastructure design for an anonymous low-latency messaging system, the Katzenpost free software project. 1 Along with the project partners and developers, we released the open access specifications of the Katzenpost design and it's open-source implementation. 2,3 Furthermore, we showed how Loopix can be used to add network-level privacy for privacy focussed cryptocurrencies like Zcash in [1], which was later also added to Katzenpost [2]. ...
... Denial-of-service attacks [3,70] -in which the attacker disrupts the service, in order to decrease the reliability of the system, and force the retransmission of messages and hence present more opportunities for attack. ...
... However, the lookup mechanism used by Salsa is susceptible to information leak attacks [116]. Moreover, Salsa is also vulnerable to the selective DoS attacks [3]. ...
Every modern online application relies on the network layer to transfer information, which exposes the metadata associated with digital communication. These distinctive characteristics encapsulate equally meaningful information as the content of the communication itself and allow eavesdroppers to uniquely identify users and their activities. Hence, by exposing the IP addresses and by analyzing patterns of the network traffic, a malicious entity can deanonymize most online communications. While content confidentiality has made significant progress over the years, existing solutions for anonymous communication which protect the network metadata still have severe limitations, including centralization, limited security, poor scalability, and high-latency. As the importance of online privacy increases, the need to build low-latency communication systems with strong security guarantees becomes necessary. Therefore, in this thesis, we address the problem of building multi-purpose anonymous networks that protect communication privacy. To this end, we design a novel mix network Loopix, which guarantees communication unlinkability and supports applications with various latency and bandwidth constraints. Loopix offers better security properties than any existing solution for anonymous communications while at the same time being scalable and low-latency. Furthermore, we also explore the problem of active attacks and malicious infrastructure nodes, and propose a Miranda mechanism which allows to efficiently mitigate them. In the second part of this thesis, we show that mix networks may be used as a building block in the design of a private notification system, which enables fast and low-cost online notifications. Moreover, its privacy properties benefit from an increasing number of users, meaning that the system can scale to millions of clients at a lower cost than any alternative solution.
... In these systems, an adversary with control of one or more of these perimeter nodes is more likely to be successful in a de-anonymization attack [21]. A particular form of attack on Tor and similar networks is suggested by Borisov et al. [7] where the attacker induces user traffic to take certain routes. For example, an attacker controlling an entry node may be able to force a client's traffic to use an exit also controlled by the attacker, and thus discover their activity. ...
... There is significant evidence that adversaries who can observe traffic at an entry and exit relay can reidentify clients in low-latency mix networks such as Tor [27,29,33,38]. An attack was described by Borisov et al. [7] which effectively denies service for routes which cannot be compromised, therefore increasing the chance of a client using a route which is vulnerable to attack. Singh et al. [34] describe eclipse attacks for overlay networks. ...
... Suppose the adversary operates a specific guard relayĝ and an exit relayx. While the adversary cannot actively dictate the route for a connection c to go througĥ x, they are free to selectively drop atĝ any connection that does not subsequently pass throughx [7]. The adversary can use flow tagging, or watermarking, to mark a flow with a sequence of packets (that do not inter-fere with the client's traffic) that are detectable at their controlled relays [31]. ...
Anonymous communication networks like Tor are vulnerable to attackers that control entry and exit nodes. Such attackers can compromise the essential anonymity and privacy properties of the network. In this paper, we consider the path bias attack– where the attacker induces a client to use compromised nodes and thus links the client to their destination. We describe an efficient scheme that detects such attacks in Tor by collecting routing telemetry data from nodes in the network. The data collection is differentially private and thus does not reveal behaviour of individual users even to nodes within the network. We show provable bounds for the sample complexity of the scheme and describe methods to make it resilient to introduction of false data by the attacker to subvert the detection process. Simulations based on real configurations of the Tor network show that the method works accurately in practice.
... For example, in BGP route poisoning is a known problem that was used in the past to direct traffic over specific ASes for eavesdropping [2,30]. Similarly, an attacker might drop session requests until a favorable dPHI path is established [5]. The biggest limitation and open problem of the dPHI protocol is the selection of the midway node. ...
The Internet infrastructure has not been built with security or privacy in mind. As a result, an adversary who has control over a single Autonomous System can set-up mass surveillance systems to gather meta data by passively collecting the headers of the messages they route. To solve this problem, lightweight anonymous routing protocols such as LAP, DOVETAIL and most recently PHI have been proposed which are efficient enough to be deployed in a large scale infrastructure such as the Internet. In this paper we take a closer look at PHI and introduce several de-anonymization attacks malicious nodes can perform to reduce the sender and receiver anonymity. As a direct consequence of this analysis we propose a new protocol called dependable PHI (dPHI). The security analysis of dPHI includes a detailed quantitative anonymity analysis that compares dPHI with PHI, LAP and HORNET. Together with the performance analysis, this allows for a good comparison of trade-offs for these anonymity protocols.
