ShadowBlock: A Lightweight and Stealthy Adblocking Browser

Shitong Zhu, Umar Iqbal, Zhongjie Wang, Zhiyun Qian, Zubair Shafiq, and Weiteng Chen

Published in The Web Conference (formerly WWW conference) 2019, 2019

As the popularity of adblocking has soared over the last few years, publishers are increasingly deploying anti-adblocking paywalls that ask users to either disable their adblockers or pay to access content. In this work we propose ShadowBlock, a new Chromium-based adblocking browser that can hide traces of adblocking activities from anti-adblockers as it removes ads from web pages. To bypass anti-adblocking paywalls, ShadowBlock takes advantage of existing filter lists used by adblockers and hides all ad elements stealthily in such a way that anti-adblocking scripts cannot detect any tampering of the ads (e.g., absence of ad elements). Specifically, ShadowBlock introduces lightweight hooks in Chromium to ensure that DOM states queried by anti-adblocking scripts are exactly as if adblocking is not employed. We implement a fully working prototype by modifying Chromium which shows great promise in terms of adblocking effectiveness and anti-adblocking circumvention but also more efficient than the state-of-the-art adblocking browser extensions. Our evaluation on Alexa top-1K websites shows that ShadowBlock successfully blocks 98.3% of all visible ads while only causing minor breakage on less than 0.6% of the websites. Most importantly, ShadowBlock is able to bypass anti-adblocking paywalls on more than 200 websites that deploy visible anti-adblocking paywalls with a 100% success rate. Our performance evaluation further shows that ShadowBlock loads pages as fast as the state-of-the-art adblocking browser extension on average.

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Recommended citation: Shitong Zhu, Umar Iqbal, Zhongjie Wang, Zhiyun Qian, Zubair Shafiq, and Weiteng Chen. 2019. ShadowBlock: A Lightweight and Stealthy Adblocking Browser. In The World Wide Web Conference (WWW ’19). Association for Computing Machinery, New York, NY, USA, 2483–2493. DOI: