20/11/2013 – Talk by Wilayat Khan

Title:  Automatic and Robust Client-Side Protection for Cookie-Based Sessions
Time: 11:00
Location: Meeting room
Type: Research Result
Speaker: Wilayat Khan
Abstract: Session cookies constitute one of the primary attack targets
against client authentication on the Web, hence modern web browsers
implement native protection mechanisms for them based on the Secure
and HttpOnly flags. While there is a general understanding about the
effectiveness of these defences, no formal result has so far proved about
the security guarantees they convey.

In this work, we have provided the first such result, with a mechanized
proof of non-interference assessing the robustness of the Secure and
HttpOnly cookie flags against both web and network attacks. We have
mechanized the proofs using the interactive theorem prover Coq.
Furthermore, we have developed CookiExt, a browser extension
that provides client-side protection against session hijacking based on
appropriate flagging of session cookies and automatic redirection over
HTTPS for HTTP requests carrying such cookies. Our solution improves
over existing client-side defences by combining protection against both
web and network attacks, while at the same time being designed so as
to minimise its effects on the user’s browsing experience.