DT-Track: 行動網路內基於域名系統查詢時間旁通道之第三方網路追蹤

由於無數的第三方網站渴望獲取網際網路使用者的網頁瀏覽紀錄，導致了目前蓬勃發展的第三方網路追蹤生態。藉由第三方網路追蹤技術，第三方網站可以取得使用者於跨網站瀏覽時的瀏覽紀錄，進以推導出該使用者之個人興趣。此舉使得第三方網站可藉由提供針對性的網頁內容與服務進以獲取更高的利潤。然而，時下大部分的行動瀏覽器皆已佈署了許多隱私保護機制以避免行動裝置使用者之瀏覽紀錄外洩，甚至提供了讓行動裝置使用者能夠自願退出第三方網路追蹤之機制。在本研究中，我們提出了基於域名系統查詢時間旁通道之第三方網路追蹤技術，並且命名為DT-Track。域名系統查詢時間旁通道源自於現今之行動作業系統與行動瀏覽器皆會對使用者所查詢之網域名稱進行快取以節省域名查詢時間以及網路頻寬。基於被行動作業系統或行動瀏覽器所快取之網域名稱與未被快取之網域名稱在查詢時間上有著顯著的差異，透過令使用者之行動瀏覽器查詢一序列的網域名稱並且測量其所需要之查詢時間，我們可以利用此域名系統查詢時間旁通道來進行第三方網路追蹤。由於此域名系統查詢時間旁通道是由現今之行動作業系統與行動瀏覽器的快取行為所導致，因此DT-Track可應用於幾乎所有的行動裝置上，而不需要依賴瀏覽器之外掛程式或是行動裝置之內部儲存空間。並且，DT-Track可輕易規避現今所佈署於行動瀏覽器與行動作業系統上的隱私保護機制。並且我們進行的系統評估驗證了DT-Track的精準性與有效性。

關鍵字

網路追蹤；隱私；網路安全

並列摘要

Burgeoning third-party web tracking campaigns are motivated by the desire of third-parties to harvest the browsing interests of Internet users. Through third-party web tracking, cross-site browsing histories can be linked together to form a complete picture of a user’s personal interests. This offers an opportunity for third-parties to deliver targeted content to increase their revenue. The majority of modern mobile browsers have adopted several privacy protection mechanisms to protect against the browsing histories being sniffed, or even to let the user opt out of the tracking campaign. In this paper, we propose a novel third-party web tracking approach, named as DT-Track, which leverages the timing difference led by the DNS caching mechanisms implemented by modern mobile browsers and operating systems. Reducing the DNS lookup time and network traffic, this caching nature can be exploited as a side channel through measuring the time required for a user in cellular networks to retrieve content from a sequence of domain names. Since the DNS-timing side channel is based on the inherent caching nature of modern mobile operating systems and browsers, DT-Track is applicable to nearly all bare vanilla browsers coming in commodity handheld devices, and it easily invalidates the major privacy protection mechanisms. Our experimental evaluation verified the accuracy and the effectiveness of DT-Track.

並列關鍵字

web tracking ； privacy ； network security

參考文獻

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國際替代計量

DT-Track: 行動網路內基於域名系統查詢時間旁通道之第三方網路追蹤

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