[Security] DNS Leak appears with HTTP Proxy

[githuber4687]

Description

Steps to Reproduce

1. Connect a HTTP Proxy in system settings
2. Visit https://browserleaks.com/ip
3. Test DNS Leak

Actual result:

Expected result(from Edge Browser):

Reproduces how often:

Every Time/Always

Brave version (brave://version info)

Brave | 1.22.70 Chromium: 89.0.4389.105

Version/Channel Information:

• Can you reproduce this issue with the current release?
  Yes
• Can you reproduce this issue with the beta channel?
  Yes
• Can you reproduce this issue with the nightly channel?
  Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
  No
• Does the issue resolve itself when disabling Brave Rewards?
  No
• Is the issue reproducible on the latest version of Chrome?
  No (even Firefox)

[hollons]

Hi @githuber4687, thanks for reporting. Do you see the same leak in chrome? Do you have DNS over HTTPS enabled? Thanks in advance.

[diracdeltas]

do you have the same DNS over HTTPS settings in Brave and Chrome? you can see your DoH settings in brave://settings/security?search=dns

[githuber4687]

Hi @githuber4687, thanks for reporting. Do you see the same leak in chrome? Do you have DNS over HTTPS enabled? Thanks in advance.

Chrome does NOT have the same DNS leak issue. I have enabled DoH with my current service provider option. Thanks for your timely help.

[githuber4687]

do you have the same DNS over HTTPS settings in Brave and Chrome? you can see your DoH settings in brave://settings/security?search=dns

Chrome does NOT have the same DNS leak issue. I have enabled DoH with my current service provider option. Thanks for your timely help.

[fmarier]

Could you try with Secure DNS explicitly disabled? That's the configuration that Chrome uses since they haven't rolled out DoH to Linux users yet due to incompatibilities with some setups.

[githuber4687]

Could you try with Secure DNS explicitly disabled? That's the configuration that Chrome uses since they haven't rolled out DoH to Linux users yet due to incompatibilities with some setups.

Thanks for your suggestion. However, the issue still exists. After switch it off, the test on Brave Browser still shows my real DNS rather than the DNS configured on my proxy sever.

[githuber4687]

@fmarier With the help of wireshark, I found that with HTTP Proxy, Brave Browser still sends DNS queries to the DNS sever that set in my router (local DHCP sever). Maybe this is the cause. Thanks for your timely help.

[diracdeltas]

cc @antonok-edm in case this may have been fixed recently with the changes to cname adblocking