One Leak Is Enough to Expose Them All - From a WebRTC IP Leak to Web-Based Network Scanning.

WebRTC provides browsers and mobile apps with rich real-time communications capabilities, without the need for further software components. Recently, however, it has been shown that WebRTC can be triggered to fingerprint a web visitor, which may compromise the user's privacy. We evaluate the feasibility of exploiting a WebRTC IP leak to scan a user's private network ports and IP addresses from outside their local network. We propose a web-based network scanner that is both browser-and network-independent, and performs nearly as well as system-based scanners. We experiment with various popular mobile and desktop browsers on several platforms and show that adversaries not only can exploit WebRTC to identify the real user identity behind a web request, but also can retrieve sensitive information about the user's network infrastructure. We discuss the potential security and privacy consequences of this issue and present a browser extension that we developed to inform the user about the prospect of suspicious activities.