Sounds like it requires that your DHCP server is hostile, which is actually a very small (though nonzero, yes) number of the attack scenarios that VPNs are designed for
"there are no ways to prevent such attacks except when the user's VPN runs on Linux or Android" is a very funny way of saying "in practice applies only to Windows and iOS".
Sounds like it requires that your DHCP server is hostile, which is actually a very small (though nonzero, yes) number of the attack scenarios that VPNs are designed for
In most situations, any host on the LAN can become a DHCP server.
“there are no ways to prevent such attacks except when the user’s VPN runs on Linux or Android” is a very funny way of saying “in practice applies only to Windows and iOS”.
No. There are certainly ways of mitigating it, but afaict no Linux distros have done so yet.
When I use a VPN, I very rarely imagine that the coffee shop / home internet that I'm hooked up to will have a malicious actor or compromised host physically inside it. I mean, maybe. But more likely is that I'm protecting against a malicious ISP, or effectively doing an extra level of authentication to my work network before I get access to non-world-visible elements of it (that shouldn't be exposed to anyone in the world that wants to poke at it). The "someone else at the cafe is malicious" case isn't un-heard of, but it's not the most common threat model. That's my point.
From the article:
When apps run on Linux there’s a setting that minimizes the effects, but even then TunnelVision can be used to exploit a side channel that can be used to de-anonymize destination traffic and perform targeted denial-of-service attacks.
"Deanonymize" and denial of service are very very different from hijacking the connection and rerouting destination traffic to a hostile device, which it sounds like are what's possible on iOS and Windows.
I don't really know the full details (e.g. what does it mean that "there's a setting", and is activating that setting starting this week any different in practice from applying the patch that will surely come this week for Windows and iOS). But it does sound fair to say that there's a serious level of vulnerability that's exclusive to Windows and iOS.
It doesn't sound to me like this really negates the purpose of a VPN, more accurately it provides a way for someone on your local network to snoop on VPN traffic, if I understand correctly.
From how the article describes the attack, someone on your local network would have to set up a malicious DHCP server/gateway. The average home user who is using a VPN to mask their public IP probably doesn't need to worry about this.
Sounds like the attack bypasses the VPN entirely. It’s not a worry on your home network if you control the DHCP server. But, on public networks, where you really should always use a VPN, you can’t be sure your traffic is going through the VPN.
Maybe, you can check a trusted site like the VPN provider’s webpage to see if you’re going through the VPN. But, a really sophisticated attack could potentially route just that traffic through the VPN and everything else outside of it.
VPNs have several purposes but the big two are hiding your traffic from attackers on the local area network and concealing your location from sites that you visit.
If you're using a VPN on wifi at a cafe and anyone else at the cafe can run a rogue DHCP server (eg, with an app on their phone) and route all of your traffic through them instead of through the VPN, I think most VPN users would say the purpose of the VPN has been defeated.