Mullvad's WebRTC check fails with "Prevent WebRTC from leaking local IP addresses" checked

tony971 commented 5 years ago

Prerequisites

[x] I verified that this is not a filter issue
- Filter issues MUST be reported at filter issue tracker
[x] This is not a support issue or a question
- Support issues and questions are handled at /r/uBlockOrigin
[x] I performed a cursory search of the issue tracker to avoid opening a duplicate issue
- Your issue may already be reported.
I tried to reproduce the issue when...
- [x] uBlock Origin is the only extension
- [x] uBlock Origin with default lists/settings
- [x] using a new, unmodified browser profile
[x] I am running the latest version of uBlock Origin
[x] I checked the documentation to understand that the issue I report is not a normal behavior

Description

Mullvad is a highly regarded VPN with an online security check. Firefox fails the site's WebRTC leak check, even when "Prevent WebRTC from leaking local IP addresses" is checked in uBlock Origin settings. Disabling WebRTC entirely passes the check.

https://am.i.mullvad.net/

[A specific URL is MANDATORY for issue happening on a web page, even if it happens "everywhere"]

Steps to Reproduce

Go to the website.
Allow the check to run.

Expected behavior:

WebRTC not to be able to leak my real IP address.

Actual behavior:

WebRTC is able to leak my real IP address.

Your environment

uBlock Origin version: 1.17.4
Browser Name and version: Firefox 65.0b9
Operating System and version: Windows 10 Pro 1809

uBlock-user commented 5 years ago

If that's how it appears, it's the expected result. Your IP address, as you can see, is not leaked.

gwarser commented 5 years ago

Requires external application or account?

If you mean: test does not work at all because WebRTC is completely disabled, then it's Firefox bug ~ https://github.com/gorhill/uBlock/issues/3009

Can be tested here: https://browserleaks.com/webrtc

tony971 commented 5 years ago

@uBlock-user it will hang on that for a minute or two and then give the result. The check takes a while.

tony971 commented 5 years ago

@gwarser No, just requires patience to allow it to finish. There is no progress bar.

uBlock-user commented 5 years ago

it will hang on that for a minute or two and then give the result

Not on my end. post what result is shown to you.

Waited 2 minutes and this is what is shown --

As expected, no leakage of IP address.

tony971 commented 5 years ago

As expected, no leakage of IP address.

That's the failure result. This is the pass (when I disable WebRTC entirely)

Edit: Posted the wrong capture

capture

uBlock-user commented 5 years ago

The issue is about WebRTC leaking IP address, not DNS Leaks test failing which appears to be a side-effect for this website given it must be using WebRTC for checking DNS leaks.

tony971 commented 5 years ago

@uBlock-user you caught my un-edited reply. I fixed the screenshot. I also get the passing message using Microsoft Edge's “Hide my local IP address over WebRTC connections” option.

uBlock-user commented 5 years ago

Posted the wrong capture

Yes, I get that too when I disable WebRTC from about:config, which is not what uBlock does, see - https://github.com/gorhill/uBlock/wiki/Prevent-WebRTC-from-leaking-local-IP-address

tony971 commented 5 years ago

@uBlock-user Microsoft Edge's “Hide my local IP address over WebRTC connections” option produces a pass without totally disabling WebRTC, either.

uBlock-user commented 5 years ago

Microsoft Edge's “Hide my local IP address over WebRTC connections” option

You mean browser option in Edge or uBlock Origin on Edge ?

tony971 commented 5 years ago

The browser option

uBlock-user commented 5 years ago

Then they're not doing what uBO does as I said before in https://github.com/uBlockOrigin/uBlock-issues/issues/377#issuecomment-453474792

The important part is not message on the website, but whether the local IP address is leaked or not. Different websites behave differently when uBO's setting is active.

You could make a suggestion to have Edge's behavior in uBO too for @gorhill to consider.

tony971 commented 5 years ago

This issue was created because whatever Microsoft Edge is doing works, but uBO does not. They're obviously doing something different because they get two different results. The failure shouldn't be dismissed as "expected behavior"

gorhill commented 5 years ago

To fix https://github.com/gorhill/uBlock/issues/3009 I intend to expose the different WebRTC options supported by the browser to the user.

uBlock-user commented 5 years ago

This issue was created because whatever Microsoft Edge is doing works, but uBO does not.

That's not the title said or the Actual Behavior you mentioned. If you want that behavior file a suggestion, you didn't file a suggestion, instead you opened this as an issue.

tony971 commented 5 years ago

An example of a pass is needed to show why a fail is an issue?

uBlock-user commented 5 years ago

Duplicate of https://github.com/gorhill/uBlock/issues/3009

uBlock-user commented 5 years ago

An example of a pass is needed to show why a fail is an issue?

Yes, when your Steps To Reproduce, Expected Behavior & Actual Behavior in the first post do not mention that.

tony971 commented 5 years ago

Failing the check is an issue in an of itself, without showing that Microsoft Edge's approach passes the check.

uBlockOrigin / uBlock-issues