Virtual private networking (VPN) companies market their services as a way to prevent anyone from snooping on your Internet usage. But new research suggests this is a dangerous assumption when connecting to a VPN via an untrusted network, because attackers on the same network could force a target’s traffic off of the protection provided by their VPN without triggering any alerts to the user.
I’m not saying it could not happen, but when you use VPN, the local network equipment does not determine protocols, the VPN infrastructure and it’s configuration in the device do. Any local connection, including the internet gateway, just serve as the road for those packets to go out or come in.
If anyone thinks I’m wrong, please let me know, I’m not 100% certain this is the case, but it is my understanding of how VPNs work.
You aren’t wrong, per se, I think you just don’t fully grasp the attack vector. This is related to DHCP option 121, which allows routes to be fed to the client when issuing the ip address required for VPN connectivity. Using this option, they can send you a preferred default route as part of the DHCP response that causes the client to route traffic out of the tunnel without them knowing.
E. It would likely only be select traffic routing out of the tunnel. I could, for example, send you routes so that all traffic destined for Chase Bank ip addresses comes back to me instead of traversing the tunnel. Much harder to detect.
Oh crap! That’s concerning as hell. I’m going to try that in my PFSense and test it with ProtonVPN, Tailscale, Wireguard to my UnRaid and NordVPN. See if maybe any of them have a way of hardening that, or at least completely dropping the packages if not.
If no VPN can be hardened for this, is there a chance that Tor or I2P can be used to avoid it instead?
Thank you very much for such a wakeup call.