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Android NAT-T keepalive offload bypasses VPN lockdown

supuk.ch

41–50 of 68 posts

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#41
post #23

[flagged]

>There is no update the GitHub issue for 2 weeks except for deleting a comment by the reporter yesterday.

Yeah, i was very confused by that, especially after they invited them to post publicly/privately. They love controlling the public communications when it comes to researchers. I remember ryrona, a guy who found VPN leaks, being censored for no reason whatsoever in their public GitHub issue tracker.

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#43
post #24
post #20

Earlier quoted context omitted.

A business: hiding everything is expected. To do otherwise is negligence An individual: you're a pedo if you use a VPN Give over.

Most people I know use a VPN do it to bypass geo restrictions and/or get a discount with cheaper currencies. (But hey, our "representatives" seem to disagree.)

sometimes it's even more basic than that

some sites really really do not like my t-mobile wireless internet IP

I think it's because t-mobile uses a small pool of IPv4 but that's just a guess

I have to use cloudflare-warp to even get on their sites (it's a free VPN)

major sites too like adidas .com

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#44

> A proper fix would require changes in the Android system. The researcher who discovered the leak has reported the issue to the Android Vulnerability Reward Program, but according to the researcher the issue was closed without action. This issue is not public, but based on this information we deem it unlikely that Google will do anything about it. GrapheneOS is aware of the issue and are working on a fix. If the acc…

[deleted]

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#46

The stupid thing about Android is that it requires you to set a PIN to use Always-on VPN which is necessary for traffic filtering (as Android doesn't provide access to nft).

That seems like a good trick to me if you want to prevent people from installing spyware without any obvious signs.

You can almost hide the warnings (there's one small notification in the bottom of the notification tray you can't disable) and on some phones even the VPN icon, but you can't hide the new lock screen code your victim suddenly needs to enter to use their phone.

It used to be that Android showed random popups and notifications about identified security risks, which were awfully annoying if you have a private CA certificate installed. Luckily Google got rid of those.

In my experience, you can also set up biometrics on basically every phone, and Google has a few "don't lock the phone while it's with you in your pocket" like services you can optionally enable as well. Your backup PIN doesn't have to be four numbers, you can put a whole passphrase in there if you want it to be secure.

You could also do facial unlock. Less secure than Apple's implementation but more than good enough if you didn't have any lock screen set before that.

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#47

The stupid thing about Android is that it requires you to set a PIN to use Always-on VPN which is necessary for traffic filtering (as Android doesn't provide access to nft).

Why wouldn't you set a PIN?

What's the point of setting a PIN if Cellebrite can hack almost any phone?

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#48
> FortiClient VPN and SmartVPN have 4,134,648 cumulative Google Play installs between them, while Google reports more than 3 billion active Android devices.

A very strange way to reason about killing an API instead of fixing the VPN issue (as someone from Google already suggested they're planning on doing). "Only 4 million people use this, we should kill it" is exactly the kind of reasoning Microsoft in the 2000s would use to kill the ability to install Linux on a PC.

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#49

Earlier quoted context omitted.

Why wouldn't you set a PIN?

What's the point of setting a PIN if Cellebrite can hack almost any phone?

Not every pocket thief or drunkard who finds your phone has cellebritr. Security measures consider the threat model.

More specifically, another commenter in this thread says it's to make sure the user is aware of the configuration of a VPN which, if done maliciously, funnels all your traffic toa a hostile place.

Re: Android NAT-T keepalive offload bypasses VPN lockdown

#50
Android has a way to bind the socket to the interface: Network.bindSocket, this is a setsockopt(SO_BINDTODEVICE) wrapper with access control.

The access to it is controlled by the VPN application. Some applications could be allowed to connect directly when the VPN is active and routing all the traffic by default, some could use VPN if configured not to use it by default.

However starting with Linux kernel 5.7, the unprivileged userspace can now call setsockopt(SO_BINDTODEVICE) directly and use VPN or non-VPN interface even if restricted by the VPN client.

Not fixed in any Android (incl. Graphene, which has fixes for other leaks, but not this) to the day.

PoC is as simple as "curl --interface [ifname, not IP] ifconfig.co" in termux.

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