Abstract-Millions of people use adblockers to remove intrusive and malicious ads as well as protect themselves against tracking and pervasive surveillance. Online publishers consider adblockers a major threat to the ad-powered "free" Web. They have started to retaliate against adblockers by employing antiadblockers which can detect and stop adblock users. To counter this retaliation, adblockers in turn try to detect and filter anti-adblocking scripts. This back and forth has prompted an escalating arms race between adblockers and anti-adblockers.We want to develop a comprehensive understanding of antiadblockers, with the ultimate aim of enabling adblockers to bypass state-of-the-art anti-adblockers. In this paper, we present a differential execution analysis to automatically detect and analyze anti-adblockers. At a high level, we collect execution traces by visiting a website with and without adblockers. Through differential execution analysis, we are able to pinpoint the conditions that lead to the differences caused by anti-adblocking code. Using our system, we detect anti-adblockers on 30.5% of the Alexa top-10K websites which is 5-52 times more than reported in prior literature. Unlike prior work which is limited to detecting visible reactions (e.g., warning messages) by anti-adblockers, our system can discover attempts to detect adblockers even when there is no visible reaction. From manually checking one third of the detected websites, we find that the websites that have no visible reactions constitute over 90% of the cases, completely dominating the ones that have visible warning messages. Finally, based on our findings, we further develop JavaScript rewriting and API hooking based solutions (the latter implemented as a Chrome extension) to help adblockers bypass state-of-the-art anti-adblockers.

User demand for blocking advertising and tracking online is large and growing. Existing tools, both deployed and described in research, have proven useful, but lack either the completeness or robustness needed for a general solution. Existing detection approaches generally focus on only one aspect of advertising or tracking (e.g. URL patterns, code structure), making existing approaches susceptible to evasion.In this work we present ADGRAPH, a novel graph-based machine learning approach for detecting advertising and tracking resources on the web. ADGRAPH differs from existing approaches by building a graph representation of the HTML structure, network requests, and JavaScript behavior of a webpage, and using this unique representation to train a classifier for identifying advertising and tracking resources. Because ADGRAPH considers many aspects of the context a network request takes place in, it is less susceptible to the single-factor evasion techniques that flummox existing approaches.We evaluate ADGRAPH on the Alexa top-10K websites, and find that it is highly accurate, able to replicate the labels of human-generated filter lists with 95.33% accuracy, and can even identify many mistakes in filter lists. We implement ADGRAPH as a modification to Chromium. ADGRAPH adds only minor overhead to page loading and execution, and is actually faster than stock Chromium on 42% of websites and AdBlock Plus on 78% of websites. Overall, we conclude that ADGRAPH is both accurate enough and performant enough for online use, breaking comparable or fewer websites than popular filter list based approaches.

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A key characteristic of commonly deployed deep packet inspection (DPI) systems is that they implement a simplified state machine of the network stack that often differs from that of endhosts. The discrepancies between the two state machines have been exploited to bypass such DPI based middleboxes. However, most prior approaches to do so rely on manually crafted adversarial packets, which not only are labor-intensive but may not work well across a plurality of DPI-based middleboxes. Our goal in this work is to develop an automated way to craft candidate adversarial packets, targeting TCP implementations in particular. Our approach to achieving this goal hinges on the key insight that while the TCP state machines of DPI implementations are obscure, those of the endhosts are well established. Thus, in our system SYMTCP, using symbolic execution, we systematically explore the TCP implementation of an endhost, identifying candidate packets that can reach critical points in the code (e.g., which causes the packets to be accepted or dropped/ignored); such automatically identified packets are then fed through the DPI middlebox to determine if a discrepancy is induced and the middlebox can be eluded. We find that our approach is extremely effective. It can generate tens of thousands of candidate adversarial packets in less than an hour. When evaluating against multiple state-of-the-art DPI systems such as Zeek and Snort, as well as a state-level censorship system, viz. the Great Firewall of China, we identify not only previously known evasion strategies, but also novel ones that were never previously reported (e.g., involving the urgent pointer). The system can be extended easily towards other combinations of operating systems and DPI middleboxes, and serves as a valuable tool for testing future DPIs' robustness against evasion attempts.

Toward resolving the source-location privacy protection issue in Wireless Sensor Networks (WSNs), a Pseudo Normal Distribution-based Phantom Routing (PNDBPR) protocol is proposed in this paper. The proposed protocol is composed of two critical phases: 1) adjusting the value of minimum-hops between a phantom node and its source, and varying the area of the phantom node distribution region at the network deployment stage; 2) generating a set of Gaussian-distributed random real numbers using the Pseudo Random Generator when the source node is transmitting data packets, and calculating the corresponding random walk hops. Theoretical analyses and simulation results show that PNDBPR can dramatically improve the diversity and the dynamicity of the phantom nodes distribution at the expense of a slight increase in communication overheads when compared with the existing PUSBRF (Source Location Privacy Preservation Protocol in Wireless Sensor Network Using Source Based Restricted Flooding) and HBDRW (A hopbased directed random walk) protocols.

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