In a recent article, Google revealed that attackers are taking advantage of a specific class of vulnerabilities derived from side-channels built into the web platform, to extract sensitive information from various web applications. Dubbed cross-site leaks (XS-Leaks), this new class of vulnerability highlights new challenges for the security of web infrastructure.
To encourage research into the issue of cross-site leaks of user information, Google has recently set up a new site for XS Leaks. It is basically a collection of browser-based side-channel attack vectors. These attack vectors highlight a set of challenges for web browser developers and security engineers, enabling the development of a comprehensive defense mechanism. The XS-Leaks wiki site basically includes information about the principles behind cross-site leaks, common attacks, and proposes defense mechanisms to stop these attacks.
The site is an open knowledge base to which the security community is invited to participate, and where experts can share information about offensive and defensive techniques. XS-Leaks takes advantage of the web’s core principle of composability. It allows websites to interact with each other and abuse legitimate mechanisms to infer information about the user. Each attack described on the site is accompanied by an overview of security features. It is believed that projects such as the XS -Leak wiki can help prevent or mitigate these attacks by providing appropriate frameworks and guidelines for security teams to counter such threats.