Sidokanalsattacker mot HTTPS

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Abstract. With software-as-a-service becoming mainstream, more and more applications are delivered to the client through the Web. Unlike a desktop application, a web application is split into browser-side and server-side components. A subset of the application’s internal information flows are inevitably exposed on the network. We show that despite encryption, such a side-channel information leak is a realistic and serious threat to user privacy. Specifically, we found that surprisingly detailed sensitive information is being leaked out from a number of high-profile, top-of-the-line web applications in healthcare, taxation, investment and web search: an eavesdropper can infer the illnesses/medications/surgeries of the user, her family income and investment secrets, despite HTTPS protection; a stranger on the street can glean enterprise employees’ web search queries, despite WPA/WPA2 Wi-Fi encryption. More importantly, the root causes of the problem are some fundamental characteristics of web applications: stateful communication, low entropy input for better interaction, and significant traffic distinctions. As a result, the scope of the problem seems industry-wide. We further present a concrete analysis to demonstrate the challenges of mitigating such a threat, which points to the necessity of a disciplined engineering practice for side-channel mitigations in future web application developments.

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Via Bruce Schnier.

Jonas Lejon

Om Jonas Lejon

En av sveriges främsta cybersäkerhetsexperter med nästan 20 års erfarenhet inom området och en bakgrund från FRA och Försvarsmakten. Kontakta mig gärna på telefonnummer 010 1889848 eller [email protected] om Er organisation behöver hjälp med cybersäkerhet. LinkedIn Twitter

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