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Chromium based browsers leak user local IP via WebRTC foundation attribute

niespodd.github.io

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Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#21

Post by easrng »

londons_explore wrote: post #18
rollcat wrote: post #6

Earlier quoted context omitted.

> How is knowing the local IP a security issue? It's a privacy issue. You can use it to fingerprint a user, local IP will give you quite many bits of entropy. https://coveryourtracks.eff.org/ > Honestly I'm not even sure if I'm surprised, but it's 2022 and we've been having this problem basically since the day WebRTC was introduced. At this point, if you care about privacy, you should probably put it in the same bag…

It's because if you don't leak the local IP, then webRTC calls will typically fail between people on the same LAN. And, if they don't fail, then they will usually have to go via a TURN server on the internet adding a lot of latency. It's a privacy/functionality tradeoff. But most people consider not being able to videocall or do online gaming with someone in the same building to not be acceptable.

They use MDNS hostnames to keep WebRTC working on LANs without leaking the IP itself, this was just an extra leak they didn't catch.

Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#22

Post by codedokode »

amenghra wrote: post #12
Semaphor wrote: post #7

Earlier quoted context omitted.

Well, the big non-adtech browser is not vulnerable, so there’s that.

https://bugzilla.mozilla.org/show_bug.cgi?id=959893 is a fun read... Firefox used to also leak the internal IP circa 2015.

Yes it is interesting how developers race to push new features allowing deanonimization of VPN users and better fingerprinting.

There is also WebGL whose main purpose is to provide user's videocard model to advertising companies and governemnt institutions.

Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#23

Post by helloooooooo »

codedokode wrote: post #20
londons_explore wrote: post #18

Earlier quoted context omitted.

It's because if you don't leak the local IP, then webRTC calls will typically fail between people on the same LAN. And, if they don't fail, then they will usually have to go via a TURN server on the internet adding a lot of latency. It's a privacy/functionality tradeoff. But most people consider not being able to videocall or do online gaming with someone in the same building to not be acceptable.

I don't think that there are many people using WebRTC especially within the same LAN, but fingerprinting is used by almost every commercial site. So I can assume that this "feature" was used in 99.99% cases for fingerprinting. This shows how browser developers race to push new features without proper estimation of privacy concerns. Luckily this was somewhat fixed by using randomized Apple mDNS names instead of IPs. B…

Corporate networks…

Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#24

Post by codedokode »

Semaphor wrote: post #14
scratcheee wrote: post #9

Earlier quoted context omitted.

I've yet to see a normally configured browser _not_ be uniquely identifiable many times over through fingerprinting. At some point it feels like trying to drain the ocean with a cup. Maybe we just need to accept that anyone who really wants to fingerprint you _can_ fingerprint you unless you use a specialist browser. At that point the solution is fairly obvious, make it legally difficult to use unique fingerprinting…

I just tried a clean FF profile with resistFingerprinting enabled. No dice. Everything adds only very few bits of identifying information (unlike my main profile which is already almost unique thanks to the accept header (English, then German)) yet it still results in 17.75 bits which according to EFF is unique. I’m agreeing with you, though I wonder, is there any way to not be unique? What would you have to do? Use…

I think a HTML-only browser without support for CSS and JS might help.

Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#25

Post by bawolff »

codedokode wrote: post #20
londons_explore wrote: post #18

Earlier quoted context omitted.

It's because if you don't leak the local IP, then webRTC calls will typically fail between people on the same LAN. And, if they don't fail, then they will usually have to go via a TURN server on the internet adding a lot of latency. It's a privacy/functionality tradeoff. But most people consider not being able to videocall or do online gaming with someone in the same building to not be acceptable.

I don't think that there are many people using WebRTC especially within the same LAN, but fingerprinting is used by almost every commercial site. So I can assume that this "feature" was used in 99.99% cases for fingerprinting. This shows how browser developers race to push new features without proper estimation of privacy concerns. Luckily this was somewhat fixed by using randomized Apple mDNS names instead of IPs. B…

> This shows how browser developers race to push new features without proper estimation of privacy concerns.

Settling on a different trade-off then you would like is not the same thing as doing it without consideration.

Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#27

Post by bawolff »

codedokode wrote: post #24
Semaphor wrote: post #14

Earlier quoted context omitted.

I just tried a clean FF profile with resistFingerprinting enabled. No dice. Everything adds only very few bits of identifying information (unlike my main profile which is already almost unique thanks to the accept header (English, then German)) yet it still results in 17.75 bits which according to EFF is unique. I’m agreeing with you, though I wonder, is there any way to not be unique? What would you have to do? Use…

I think a HTML-only browser without support for CSS and JS might help.

How many people do you know run html only browsers? Not having CSS would be extremely uniquely identifying.

Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#28

Post by tyingq »

Semaphor wrote: post #2

What’s the issue there? How is knowing the local IP a security issue? And FWIW, the local IP does not get leaked when using a VPN. (edit: Or rather, the VPN local IP gets leaked. Same question, no idea if that’s security relevant in some way?) edit: Thanks everyone, I completely forgot about fingerprinting.

Have a look at this that scans your local network: http://samy.pl/webscan/

I think some browser changes might have hobbled it a bit, but it was startling when I first tried it.

Re: Chromium based browsers leak user local IP via WebRTC foundation attribute

#29

Post by coldtea »

bawolff wrote: post #25
codedokode wrote: post #20

Earlier quoted context omitted.

I don't think that there are many people using WebRTC especially within the same LAN, but fingerprinting is used by almost every commercial site. So I can assume that this "feature" was used in 99.99% cases for fingerprinting. This shows how browser developers race to push new features without proper estimation of privacy concerns. Luckily this was somewhat fixed by using randomized Apple mDNS names instead of IPs. B…

> This shows how browser developers race to push new features without proper estimation of privacy concerns. Settling on a different trade-off then you would like is not the same thing as doing it without consideration.

In this case, it is blatant disregard.
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