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uBlock + Firefox = DNS Leaking #1743

Closed
8 tasks done
snoitallicso opened this issue Oct 1, 2021 · 14 comments
Closed
8 tasks done

uBlock + Firefox = DNS Leaking #1743

snoitallicso opened this issue Oct 1, 2021 · 14 comments
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external issue involving an external factor Firefox specific to Firefox fixed issue has been addressed

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@snoitallicso
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Prerequisites

I tried to reproduce the issue when...

  • uBO is the only extension
  • uBO with default lists/settings
  • using a new, unmodified browser profile

Description

Settings:

Proxy DNS when using SOCKS v5 = true

Enable DNS over HTTPS = true

Provider DNS: NextDNS, Cloudflare (it doesn't matter even if it on/off)

I'm using proxy extension to get one stricted by country website and find out that it can detect my actual IP without problem. At forums root of the problem named by DNS is leaking.

At first time I was thinking that problem can be fixed by about:config (to fix WebRTC Leaking), so I switch:

Set these to False

about:config?filter=media.peerconnection.enabled
about:config?filter=media.peerconnection.use_document_iceservers
about:config?filter=media.peerconnection.video.enabled
about:config?filter=webgl.enable-webgl2
Set these to True
about:config?filter=media.peerconnection.turn.disable
about:config?filter=webgl.disabled
Set to 1
about:config?filter=media.peerconnection.identity.timeout

But problem is not going away.

After that I switch over 6 proxy extensions with dozen of the countries.

But that doesn't change anything. So I started to disable extensions and check… And I solve my problem as uBlock was disabled!

I like uBlock and do not want it to change for ADBP etc.

Can you fix that issue?

P.S. at Chrome this problem doesn't appear.

A specific URL where the issue occurs

https://surfshark.com/dns-leak-test

Steps to Reproduce

  1. Install a proxy extension
  2. Install ublock
  3. Go to https://surfshark.com/dns-leak-test
  4. Now disable ublock and retest

Expected behavior

My ISP's original IP shouldn't be available for public.

Actual behavior

Proxy IP + ISP's available for web services.

uBlock Origin version

1.37.2

Browser name and version

Firefox 92.0.1 / 94.0a1 (2021-09-30)

Operating System and version

Windows 10

@snoitallicso
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Enable uBlock
Disable uBlock

@snoitallicso
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94a
92

@gorhill
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gorhill commented Oct 1, 2021

Install a proxy extension

That is your issue, use a system-wide proxy or disable uBO's "Uncloak canonical names". When you use a proxy extension, there is no guarantee that other extensions will have their own network requests go through another proxy extension -- extensions cannot affect each other.

@gorhill gorhill closed this as completed Oct 1, 2021
@snoitallicso
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Install a proxy extension

That is your issue, use a system-wide proxy or disable uBO's "Uncloak canonical names". When you use a proxy extension, there is no guarantee that other extensions will have their own network requests go through another proxy extension -- extensions cannot affect each other.

There is no problem using proxy extension without uBlock!

@gorhill
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gorhill commented Oct 1, 2021

Disable "Uncloak canonical names" and report the result.

@gorhill
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gorhill commented Oct 1, 2021

Also, be more specific:

Install a proxy extension

Provide an exact URL to such extension.

@snoitallicso
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Uncloak canonical names

Problem solved. Please add information inside help popup for such issues?

Also, be more specific:

Install a proxy extension

Provide an exact URL to such extension.

Any top proxy extension from addons.mozilla.org

@uBlock-user uBlock-user added external issue involving an external factor Firefox specific to Firefox labels Oct 1, 2021
@gorhill
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gorhill commented Oct 1, 2021

The issue is only with proxy/vpn extensions, there is no issue with system-wide proxy/vpn.

@uBlock-user uBlock-user added the invalid not a uBlock issue label Oct 1, 2021
@gorhill gorhill reopened this Oct 1, 2021
@uBlock-user uBlock-user removed the invalid not a uBlock issue label Oct 1, 2021
@gorhill
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gorhill commented Oct 1, 2021

I installed Hola Free VPN Proxy Unblocker, and when uBO does a DNS query to resolve to cnames, there is a proxyInfo property on the request details object.

Those per-site proxy extensions are probably using proxy.onRequest, hence why uBO's internal DNS queries do not go through the proxy. There is no magic solution for uBO disabling cname-uncloaking if the proxyInfo property is present, as the proxyInfo property may also exist when a there is a system-wide or browser-wide proxy configuration in effect. The issue is per-site proxying through an extension.

What I could do is add a sub setting "Disable the uncloaking of canonical names for proxied requests" to avoid the kind of surprise here (the imperfect proxying when done through an extension).

@uBlock-user
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same as #911 ?

@gorhill
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gorhill commented Oct 1, 2021

Not the same, #911 was fixed by Firefox -- the issue was uBO's DNS queries were bypassing the browser-wide settings. This is fixed.

Here the issue is uBO's DNS query not being proxied by another extension doing the proxying on-the-fly through proxy.onRequest(), which is expected as extensions can't interfere which each other's requests -- there is no way for uBO to know whether the proxying was done on-the-fly or is browser-wide.

A solution for this would be for Firefox to indicate with a property in the proxyInfo object whether the proxying was done on-the-fly, in which case uBO could avoid making a DNS query.

@uBlock-user uBlock-user added the something to address something to address label Oct 1, 2021
@ghost
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ghost commented Oct 5, 2021

There is no such issue with OpenVPN.

@uBlock-user
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uBlock-user commented Sep 11, 2024

@MasterKia MasterKia added fixed issue has been addressed and removed something to address something to address labels Sep 11, 2024
@mb
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mb commented Sep 23, 2024

https://bugzilla.mozilla.org/show_bug.cgi?id=1910593 isn't a fix for the DNS leak described in this bug. I verified that the leak described in this issue still occurs in Firefox Nightly 132.0a1 (2024-09-18), where Bug 1910593 is fixed. The fix in uBlock gorhill/uBlock@d5f14ff pending for the next release is still necessary.

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