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.
For this scenario, are you imagining that a person may have physically entered the coffee shop who’s both tech savvy and malicious enough to run a malicious device there?
Or were you thinking a remote compromise of their router? That one seems moderately more probable, but eliminates anything special about the coffee shop’s router specifically as opposed to your home router or your workplace’s router.
For this scenario, are you imagining that a person may have physically entered the coffee shop who’s both tech savvy and malicious enough to run a malicious device there?
I mean… Yeah. I’ve sat in a coffee shop or airport in the past and sniffed traffic out of mere curiosity. Why wouldn’t a malicious actor be there?
I have done, and friends of mine have done a lot more than that. My point is that I’m unusually nerdy and the number of people who’ve ever been subjected to it by me being near them is probably in the double digits for a few minutes over my entire life.
I will bet you any amount of money that you can go to any coffee shop and set up an insecure VPN there all day and not a single person will randomly come in, set up a malicious DHCP server, and reroute the VPN traffic through their hardware so they can spoof it and spy on your traffic.
The fact that it’s possible means it’s worth defending against, sure. If it sounds like I’m saying it’s not a big deal I am not. I’m just saying that it is not the most common threat that you need to defend against most urgently or even in the top 10 (primarily because it requires one of this little handful of people nearby to you to be a malicious actor, where most of the ones that are really commonly-encountered threats are the ones that literally any one of billions of people on the planet could at any time randomly target you with, so you’re going to run into a lot more frequently.)
I can enumerate the ISPs that have will-hand-your-traffic-over-for-general-vacuuming-up deals with the American government, and the ISPs worldwide that do some form of traffic editing on behalf of differently-repressive-than-the-US regimes, and I can go to Starbucks tomorrow and we can compare that proportion of ISPs to the proportion of people I find actively tampering with my traffic from the cafe.
In most situations, any host on the LAN can become a DHCP server.
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:
“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.
That’s like 90% of the reason to actually use a VPN at a coffee shop.
For this scenario, are you imagining that a person may have physically entered the coffee shop who’s both tech savvy and malicious enough to run a malicious device there?
Or were you thinking a remote compromise of their router? That one seems moderately more probable, but eliminates anything special about the coffee shop’s router specifically as opposed to your home router or your workplace’s router.
I mean… Yeah. I’ve sat in a coffee shop or airport in the past and sniffed traffic out of mere curiosity. Why wouldn’t a malicious actor be there?
I have done, and friends of mine have done a lot more than that. My point is that I’m unusually nerdy and the number of people who’ve ever been subjected to it by me being near them is probably in the double digits for a few minutes over my entire life.
I will bet you any amount of money that you can go to any coffee shop and set up an insecure VPN there all day and not a single person will randomly come in, set up a malicious DHCP server, and reroute the VPN traffic through their hardware so they can spoof it and spy on your traffic.
The fact that it’s possible means it’s worth defending against, sure. If it sounds like I’m saying it’s not a big deal I am not. I’m just saying that it is not the most common threat that you need to defend against most urgently or even in the top 10 (primarily because it requires one of this little handful of people nearby to you to be a malicious actor, where most of the ones that are really commonly-encountered threats are the ones that literally any one of billions of people on the planet could at any time randomly target you with, so you’re going to run into a lot more frequently.)
Sorry - but you think
I’d take that bet.
Okay, how much?
I can enumerate the ISPs that have will-hand-your-traffic-over-for-general-vacuuming-up deals with the American government, and the ISPs worldwide that do some form of traffic editing on behalf of differently-repressive-than-the-US regimes, and I can go to Starbucks tomorrow and we can compare that proportion of ISPs to the proportion of people I find actively tampering with my traffic from the cafe.