Biblio

We present research on the security of the most popular websites, ranked according to Alexa's top one million list, based on an HTTP response headers analysis. For each of the domains included in the list, we made four different requests: an HTTP/1.1 request to the domain itself and to its "www" subdomain and two more equivalent HTTPS requests. Redirections were always followed. A detailed discussion of the request process and main outcomes is presented, including X.509 certificate issues and comparison of results with equivalent HTTP/2 requests. The body of the responses was discarded, and the HTTP response header fields were stored in a database. We analysed the prevalence of the most important response headers related to web security aspects. In particular, we took into account Strict- Transport-Security, Content-Security-Policy, X-XSS-Protection, X-Frame-Options, Set-Cookie (for session cookies) and X-Content-Type. We also reviewed the contents of response HTTP headers that potentially could reveal unwanted information, like Server (and related headers), Date and Referrer-Policy. This research offers an up-to-date survey of current prevalence of web security policies implemented through HTTP response headers and concludes that most popular sites tend to implement it noticeably more often than less popular ones. Equally, HTTPS sites seem to be far more eager to implement those policies than HTTP only websites. A comparison with previous works show that web security policies based on HTTP response headers are continuously growing, but still far from satisfactory widespread adoption.

Recent incidents have once again brought the topic of encryption to public discourse, while researchers continue to demonstrate attacks that highlight the difficulty of implementing encryption even without the presence of "backdoors". However, apart from the threat of implementation flaws in encryption libraries, another significant threat arises when web services fail to enforce ubiquitous encryption. A recent study explored this phenomenon in popular services, and demonstrated how users are exposed to cookie hijacking attacks with severe privacy implications. Many security mechanisms purport to eliminate this problem, ranging from server-controlled options such as HSTS to user-controlled options such as HTTPS Everywhere and other browser extensions. In this paper, we create a taxonomy of available mechanisms and evaluate how they perform in practice. We design an automated testing framework for these mechanisms, and evaluate them using a dataset of 30 days of HTTP requests collected from the public wireless network of our university's campus. We find that all mechanisms suffer from implementation flaws or deployment issues and argue that, as long as servers continue to not support ubiquitous encryption across their entire domain (including all subdomains), no mechanism can effectively protect users from cookie hijacking and information leakage.