Apple WebKit vulnerabilities reveal your IP address, despite Private Relay
Brief
Three WebKit mechanisms have been discovered to bypass Apple’s iCloud Private Relay. In fact, the mechanisms can bypass any browser‑level proxy configuration, including Psylo’s proxy, Tor-on-iOS proxy setups, and so on.
Private Relay is a VPN-like system for Safari on iOS which is meant to prevent websites from viewing the visitor’s IP address and location.
But because all three methods described by the researchers occur outside WebKit’s normal page loading path, Apple’s iCloud Private Relay never sees them and, as a result, means you can’t hide your IP address or Domain Name System (DNS) path in these cases.
The three features are:
- DNS prefetching
Modern browsers try to be faster by looking up the IP addresses of links on a page before you click them, a feature known as DNS prefetching.