A security researcher says that Apple’s iOS devices don’t fully route all network traffic through VPNs as a user might expect, a potential security issue the device maker has known about for years. From a report: Michael Horowitz, a longtime computer security blogger and researcher, puts it plainly — if contentiously — in a continually updated blog post. “VPNs on iOS are broken,” he says. Any third-party VPN seems to work at first, giving the device a new IP address, DNS servers, and a tunnel for new traffic, Horowitz writes. But sessions and connections established before a VPN is activated do not terminate and, in Horowitz’s findings with advanced router logging, can still send data outside the VPN tunnel while it’s active.
In other words, you might expect a VPN client to kill existing connections before establishing a secure connection so they can be re-established inside the tunnel. But iOS VPNs can’t seem to do this, Horowitz says, a finding that is backed up by a similar report from May 2020. “Data leaves the iOS device outside of the VPN tunnel,” Horowitz writes. “This is not a classic/legacy DNS leak, it is a data leak. I confirmed this using multiple types of VPN and software from multiple VPN providers. The latest version of iOS that I tested with is 15.6.”