arXiv subjects

Alex C. Snoeren

Publications and source records attributed to Alex C. Snoeren.

7 recordsLinked to original sources

arXiv2025

Country-in-the-Middle: Measuring Paths between People and their Governments

Understanding where Internet services are hosted, and how users reach them, has captured the interest of government regulators and others concerned with the privacy of data flows. In this paper we focus on government websites -- services which arguably merit a higher expectation of protection against foreign surveillance or interference -- and seek to identify countries in the middle (CitMs): countries that are neither the source nor destination in a path for a resident visiting their online government services. Finding these CitMs raises daunting methodological challenges. We propose a framework to identify CitMs and use a pilot study of 149 countries to refine our methodology before conducting an in-depth measurement study of 11 countries. For our focused study, we compile an extensive set of websites hosting government services and analyze over 9,000 IP-level paths from vantage points in those countries to these services. We conduct extensive manual validation to corroborate or discard paths based on the aforementioned challenges, and discuss paths that experience unexpected CitMs.

cs.NI↗

arXiv2025

Local Frames: Exploiting Inherited Origins to Bypass Content Blockers

We present a study of how local frames (i.e., iframes loading content like "about:blank") are mishandled by a wide range of popular Web security and privacy tools. As a result, users of these tools remain vulnerable to the very attack techniques against which they seek to protect themselves, including browser fingerprinting, cookie-based tracking, and data exfiltration. The tools we study are vulnerable in different ways, but all share a root cause: legacy Web functionality interacts with browser privacy boundaries in unexpected ways, leading to systemic vulnerabilities in tools developed, maintained, and recommended by privacy experts and activists. We consider four core capabilities supported by most privacy tools and develop tests to determine whether each can be evaded through the use of local frames. We apply our tests to six popular Web privacy and security tools -- identifying at least one vulnerability in each for a total of 19 -- and extract common patterns regarding their mishandling of local frames. Our measurement of popular websites finds that 56% employ local frames and that 73.7% of the requests made by these local frames should be blocked by popular filter lists but instead trigger the vulnerabilities we identify. From another perspective, 14.3% of all sites that we crawl make requests that should be blocked inside of local frames. We disclosed these vulnerabilities to the tool authors and discuss both our experiences working with them to patch their products and the implications of our findings for other privacy and security research.

cs.CR↗

arXiv2025

Words as Geometric Features: Estimating Homography using Optical Character Recognition as Compressed Image Representation

Document alignment and registration play a crucial role in numerous real-world applications, such as automated form processing, anomaly detection, and workflow automation. Traditional methods for document alignment rely on image-based features like keypoints, edges, and textures to estimate geometric transformations, such as homographies. However, these approaches often require access to the original document images, which may not always be available due to privacy, storage, or transmission constraints. This paper introduces a novel approach that leverages Optical Character Recognition (OCR) outputs as features for homography estimation. By utilizing the spatial positions and textual content of OCR-detected words, our method enables document alignment without relying on pixel-level image data. This technique is particularly valuable in scenarios where only OCR outputs are accessible. Furthermore, the method is robust to OCR noise, incorporating RANSAC to handle outliers and inaccuracies in the OCR data. On a set of test documents, we demonstrate that our OCR-based approach even performs more accurately than traditional image-based methods, offering a more efficient and scalable solution for document registration tasks. The proposed method facilitates applications in document processing, all while reducing reliance on high-dimensional image data.

cs.CV↗

arXiv2023

Rosebud: Making FPGA-Accelerated Middlebox Development More Pleasant

We introduce an approach to designing FPGA-accelerated middleboxes that simplifies development, debugging, and performance tuning by decoupling the tasks of hardware-accelerator implementation and software-application programming. Rosebud is a framework that links hardware accelerators to a high-performance packet processing pipeline through a standardized hardware/software interface. This separation of concerns allows hardware developers to focus on optimizing custom accelerators while freeing software programmers to reuse, configure, and debug accelerators in a fashion akin to software libraries. We show the benefits of the Rosebud framework by building a firewall based on a large blacklist and porting the Pigasus IDS pattern-matching accelerator in less than a month. Our experiments demonstrate that Rosebud delivers high performance, serving ~200 Gbps of traffic while adding only 0.7-7 microseconds of latency.

cs.AR↗

arXiv2022

Quantifying Nations Exposure to Traffic Observation and Selective Tampering

Almost all popular Internet services are hosted in a select set of countries, forcing other nations to rely on international connectivity to access them. We infer instances where traffic towards a large portion of a country is serviced by a small number of Autonomous Systems, and, therefore, may be exposed to observation or selective tampering. We introduce the Country-level Transit Influence (CTI) metric to quantify the significance of a given AS on the international transit service of a particular country. By studying the CTI values for the top ASes in each country, we find that 32 nations have transit ecosystems that render them particularly exposed, with traffic destined to over 40% of their IP addresses privy to a single AS. In the nations where we are able to validate our findings with in-country operators, we obtain 83% accuracy on average. In the countries we examine, CTI reveals two classes of networks that play a particularly prominent role: submarine cable operators and state-owned ASes.

cs.NI↗

arXiv2019

Expanding across time to deliver bandwidth efficiency and low latency

Datacenters need networks that support both low-latency and high-bandwidth packet delivery to meet the stringent requirements of modern applications. We present Opera, a dynamic network that delivers latency-sensitive traffic quickly by relying on multi-hop forwarding in the same way as expander-graph-based approaches, but provides near-optimal bandwidth for bulk flows through direct forwarding over time-varying source-to-destination circuits. The key to Opera's design is the rapid and deterministic reconfiguration of the network, piece-by-piece, such that at any moment in time the network implements an expander graph, yet, integrated across time, the network provides bandwidth-efficient single-hop paths between all racks. We show that Opera supports low-latency traffic with flow completion times comparable to cost-equivalent static topologies, while delivering up to 4x the bandwidth for all-to-all traffic and supporting 60% higher load for published datacenter workloads.

cs.NI↗

arXiv2014

Lost in Space: Improving Inference of IPv4 Address Space Utilization

One challenge in understanding the evolution of Internet infrastructure is the lack of systematic mechanisms for monitoring the extent to which allocated IP addresses are actually used. In this paper we try to advance the science of inferring IPv4 address space utilization by analyzing and correlating results obtained through different types of measurements. We have previously studied an approach based on passive measurements that can reveal used portions of the address space unseen by active approaches. In this paper, we study such passive approaches in detail, extending our methodology to four different types of vantage points, identifying traffic components that most significantly contribute to discovering used IPv4 network blocks. We then combine the results we obtained through passive measurements together with data from active measurement studies, as well as measurements from BGP and additional datasets available to researchers. Through the analysis of this large collection of heterogeneous datasets, we substantially improve the state of the art in terms of: (i) understanding the challenges and opportunities in using passive and active techniques to study address utilization; and (ii) knowledge of the utilization of the IPv4 space.

cs.NI↗