According to a security researcher, iOS persistently bypasses some connections through the VPN tunnel. The problem has existed for years.
Apparently, iPhones and iPads do not always route all data traffic through an activated VPN. Security researcher Michael Horowitz explains that certain connections that exist before the VPN tunnel is set up are maintained bypassing it and could reveal the IP address, for example. The problem can be observed regardless of the VPN service used. He tested this several times over months with an iPad without a mobile connection, most recently again with the current version iOS or iPadOS 15.6.
Connections to Apple’s push server and Gmail
According to the analysis, not only connections to Apple servers – such as the manufacturer’s push message service – can be observed outside the VPN tunnel, but also, for example, connections to Google’s Gmail for a configured account.
Data leaves the iOS device outside the VPN tunnel, emphasizes Horowitz, VPN apps are “broken in iOS” as a result. According to the security researcher, he had already informed Apple about the problem in May, but had not received a concrete answer even after weeks – neither a confirmation or rejection of the observed behavior nor an announcement for a correction.
Similar issue reported by ProtonVPN
Horowitz points out that the VPN service ProtonVPNn already reported about a very similar problem two years ago. A VPN cannot reliably close the connections in iOS and then re-establish them in a tunnel, so certain connections outside of the VPN remain open, it was said at the time – as of iOS 13. Apple had introduced a kill switch capability for developers, Proton wrote for several months later and promised to integrate the feature. Workarounds like turning Airplane Mode on and off after activating the VPN don’t seem to provide a reliable remedy. According to the security researcher, VPN providers like Windscribe also know about the behavior and have also contacted Apple.
