Novel attack against virtually all VPN apps neuters their entire purpose

jeffw@lemmy.world to Technology@lemmy.world – 494 points –
Novel attack against virtually all VPN apps neuters their entire purpose
arstechnica.com
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"There are no ways to prevent such attacks except when the user's VPN runs on Linux or Android."

So there are ways.

Common Linux w

Not really, Linux is still vulnerable and there is a mitigation but it opens a side channel attack.

Wait so the vulnerability exists on macos and iphone even though those are based on bsd (right?)

Edit: and also Windows, forgot about Windows

Hilariously enough, Windows users can use WSL to run a Linux VPN (but only applications running in WSL are safe if I understand the attack right)

True, if you neg a linux dev online enough for two years, you can make your entire infrastructure vulnerable to attack

Hate to rain on the Linux parade here, but didn't the article say: "There are no ways to prevent such attacks except when the user's VPN runs on Android." and that Linux was just as vulnerable as Windows?

It's not as vulnerable but it still is.

Interestingly, Android is the only operating system that fully immunizes VPN apps from the attack because it doesn't implement option 121. For all other OSes, there are no complete fixes. 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.

But in the details this attack is not that bad. E.g. NordVPN and I guess also other VPNs use firewall rules to drop traffic on normal network interfaces.

Their side channel is still routing traffic away from the VPN channel. Then they can observe that there is no traffic and guess that the user either didn't make requests in that moment or that he wanted to visit a website in the range covered by the route. They can not spy on the traffic.

Also you can not quickly move into a network and apply this attack, as DHCP leases usually last 1 day or at least 1 hour. Only when they expire you can apply the attack (or you force the user to drop from the network, which is easy if they are using WPA2, but only possible by blocking the wifi signal if they are using WPA3)

It is a serious issue and should be mitigated, but not as huge as news articles make it.

You can also use network namespaces on Linux which Wireguard has a nice explanation and walkthrough on, recommending this as part of setting up wg connections. https://www.wireguard.com/netns/

I saw that but unfortunately it doesn't detail how to set it up persistently on every boot. And I also haven't seen anybody using this method, probably because of the lack of tooling around it. For example afaik the official Mullvad client on linux just uses a firewall.

you're replying to a verbatim quote from the article.

I was going from this: (emphasis mine)

Interestingly, Android is the only operating system that fully immunizes VPN apps from the attack because it doesn't implement option 121. For all other OSes, there are no complete fixes. 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.