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Attackers can decloak routing-based VPNs

leviathansecurity.com

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Re: Attackers can decloak routing-based VPNs

#161

Earlier quoted context omitted.

Beware that despite all marketing statements, VPN providers can easily be forced to store logs using court orders, even if they don't do it by default.

You can always shut down rather than do so - it's happened in the US.

This also happened with providers in Europe. So you can safely assume that any VPN provider who is still doing business in Europe is compromised in some way or another by the government.

Re: Attackers can decloak routing-based VPNs

#163

Earlier quoted context omitted.

Mullvad complies, but they go out of their way to keep very little information. If you don't have the information in the first place, you can't surrender it.

Beware that despite all marketing statements, VPN providers can easily be forced to store logs using court orders, even if they don't do it by default.

> VPN providers can easily be forced to store logs using court orders

It's not grave if the provider is allowed to notify the user that logs are being collected from now on.

Is there a country where gag orders are unconstitutional or something of that sort?

Re: Attackers can decloak routing-based VPNs

#164
post #10

The threat model is that an arbitrary attacker can somehow become the DHCP server on your LAN, which is unlikely but not impossible. On the other hand, if you are using an ISP provided gateway device..

> arbitrary attacker can somehow become the DHCP server on your LAN, which is unlikely but not impossible Coffee shop wi-fi? A.k.a merely the no. 1 selling point for most VPN offerings. The proper course of action in this case is to use your 4G/5G connection and not to connect to shady networks you don't trust.

> Coffee shop wi-fi? A.k.a merely the no. 1 selling point for most VPN offerings.

Isn't the #1 selling point of general consumer's (not Enterprise) VPNs to stream video and audio from another country?

Re: Attackers can decloak routing-based VPNs

#165
post #143

Earlier quoted context omitted.

Can you expand on that? Specifically the affiliation with Nordic countries? I’m a Nord VPN customer, I’d quite like to know more — may help inform any future decision on renewing or even staying with them.

In general, Nordic countries are known for their extensive privacy laws, which in theory would make it harder for law enforcement to gain access to your traffic (and with a court order it is very easy to decloak your VPN traffic). However, as all Nordic countries are part of the Schengen Area, they are bound by European laws - and their enforcement. When Europol started cracking down on VPN providers that didn't comp…

So, should they be requested to do so by a formally issued court order, they would comply and start logging a user’s activity, but do not do so by default.

Calling them worthless at providing secure browsing seems far-fetched; calling them a scam is fully disingenuous.

Re: Attackers can decloak routing-based VPNs

#166

Earlier quoted context omitted.

You're spreading FUD, the Swedish government can't do shit to Mullvad but take their servers offline. Possibly if it was a matter of national security, at which point our recommendations are useless either way.

False. Like all member states, the Swedish government has officialy ceded jurisdiction and enforcement of certain laws to the EU. Only VPN providers who do not comply with such international court orders get shut down. Look at what happened to vpnlab: The police literally write on their seized domain that they have forcefully attained access to everything, because the provider would not give it away freely: https://v…

You presume that a) all governments are bad, b) law is controlled by these governments and c) we only have to hide from governments.

Neither are absolutely true.

I mostly trust my (western european) government to not fuck me over when I am abiding the laws. Which I mightn't always do. I mostly trust them to be proportional: e.g. not beat me up or throw me in prison for smoking a spliff or drinking in public.

A court order is handled by courts. Which, at least in most European countries, is independent. This is shifting in some countries, but that's a rather big deal. "Cut of from EU benefits" big. Regardless what police or governments want, they have to abide by laws. And courts decisions on allowing access to my internet usage.

While in many countries governments are truly life threatening to minorities, that's not the only privacy concern. I have much more to "fear" from my ISP selling out, my datacenter getting bought by a FAANG or just those FAANGs spying on my every move.

What I'm trying to say is: you are spreading FUD by inventing some absolutisms that are really a spectrum for most common VPN users.

Also: VPNs have always known to be detrimental to your security when browsing "really" secure: through TOR.

Re: Attackers can decloak routing-based VPNs

#167
The "attack" is just a clever use of DHCP option 121. It's a valid attack against a badly broken client configuration. Just replacing the default route (or overwriting it with two /1 routes) and adding a host route to the VPN endpoint is not secure. To properly isolate the encapsulated traffic from the underlaying network you have to use proper policy based routing (e.g. Linux network namespaces, FreeBSD vnet, OpenBSD rdomains). Attempting to cobble together something with packet filters and a userspace "kill switch" is broken by design and just shows how little the common VPN hosters understand or care about their supposed core competency. Good old enumerating badness strikes again.

Re: Attackers can decloak routing-based VPNs

#168

Earlier quoted context omitted.

Mullvad complies, but they go out of their way to keep very little information. If you don't have the information in the first place, you can't surrender it.

Beware that despite all marketing statements, VPN providers can easily be forced to store logs using court orders, even if they don't do it by default.

That still has value, it's much harder to do drag-net style surveillance if you need court orders to collect new information and can't scoop up old information.

Re: Attackers can decloak routing-based VPNs

#169

Earlier quoted context omitted.

You can always shut down rather than do so - it's happened in the US.

This also happened with providers in Europe. So you can safely assume that any VPN provider who is still doing business in Europe is compromised in some way or another by the government.

"Compromised" is a wrong word to use, unless you consider any obedience to the law "compromise". VPN providers who are still doing business in EU (not Europe) do obey court orders - that would be more correct wording. Any non-compliance is a one-time occurence: either you decide to cease operations or you are forced to cease operations by LEA, as in vpnlab.net example.

Re: Attackers can decloak routing-based VPNs

#170

Earlier quoted context omitted.

I think you missed a step in your progression. Step one, you connect to the network and get routes. Step two, you connect your VPN. Step three, your host starts sending traffic. At this point, your firewall rules are now active and dropping any traffic you've told them to. Step four, you renew your DHCP lease and get new routes via option 121. Those routes might be malicious, or they might not. One of three things is…

No, you're wrong again. I just tested this (simulating routes added by a DHCP option 121) and it works exactly as I said. C is what happens. But it doesn't happen the way you say at all. Only the traffic heading to the new 121 routes are blocked - why is it blocked? because the routes are on the physical interface, and the firewall rules blocks all off-VPN traffic (except traffic to the VPN endpoint itself) The tunne…

Could you please show me a rule so I can "try it"? I'd love it if this worked.

Let's say:

- the physical interface name is "wlan0"

- the VPN virtual interface name is "tun0"

- the VPN server is 10.1.1.1 on TCP port 8888

- the DHCP server on initial lease sends "0.0.0.0/0 via 10.8.8.8"

- the DHCP server on renew sends the above rule and also "10.0.0.0/8 via 10.9.9.9"

- Before the renew, traffic not routed via 10.8.8.8 is blocked

- After the renew, traffic with a destination IP matching 10.0.0.0/8 not routed via 10.9.9.9 is blocked

What should the firewall rule look like to let the VPN connection stay up both before and after the new rule, while also ensuring that traffic to 10.7.7.7 goes via the VPN and not via 10.9.9.9 or 10.8.8.8?

EDIT: you keep saying "I'm wrong" but I'm just asking how this firewall rule can be structured to do what you say. It occurs to me that perhaps you're saying you can make traffic for 10.7.7.7 get blocked. But in the above, and before, what I'm asking for is how to make traffic for 10.7.7.7 continue to get sent over the VPN after the new rule addition, just like it was before - in other words, no dropped packets.

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