Unwanted fallback to www.google.com:80 if redirector.brave.com is unresponsive

[fmarier]

Description

If redirector.brave.com is unresponsive (e.g. returning a 503), the browser will fall back to www.google.com:80 (yes, unencrypted HTTP) for component updates.

Steps to Reproduce

This is how I did it on a Linux machine:

1. Put this line in /etc/hosts: 127.0.0.1 redirector.brave.com
2. Start an interception proxy: mitmproxy --mode socks5 --listen-port 9000
3. Start Brave (new profile): brave-browser-stable --user-data-dir=/home/francois/brave-temp-profile --proxy-server="socks5://localhost:9000"

Actual result:

Then you should immediately see two HTTP (port 80) requests to www.google.com:

GET http://www.google.com/dl/release2/chrome_component/acknfovcvghy2mrucp77wk2gl3la_7957/hfnkpimlhhgieaddgfemjhofmfblmnib_7957_all_adzjna7hdabpdzvqlsg4kn5wn73a.crx3
GET http://www.google.com/dl/release2/chrome_component/prikcrkh6jeqqkyjq6gvwcop64_58/khaoiebndkojlmppeemjhbpbandiljpe_58_linux_bnsevftmao3ole3oz24w3p7u74.crx3

The first one refers to CRLsets (a TLS component) while the second one is part of Safe Browsing (the File Type Policies component).

Later we see these components being downloaded using the HTTP fallback:

• Safety Tips
• Crowd Deny
• PKI Metadata
• Hyphenation

Expected result:

If the connection to redirector.brave.com fails, the browser should simply give up and not update the components.

Desktop Brave version:

Brave	1.50.119 Chromium: 112.0.5615.121 (Official Build) (64-bit) 
Revision	39cc4e45904ae9f1741c4fbaa866e629c96f2268-refs/branch-heads/5615_51@{#8}
OS	Linux

Android Device details:

I didn't test on Android, but I suspect it has the same fallback.

[stoletheminerals]

Can confirm it falls back to www.google.com:80 on Android
Steps to reproduce, using a real device:

On desktop machine (macos or linux):

1. Put this line in /etc/hosts: 127.0.0.1 redirector.brave.com
2. Start an interception proxy: mitmproxy --mode regular --listen-port 9000 (Alternatively use another proxy software, such as Charles (default proxy port is 8888))

On Android device :

1. Make sure Brave is not installed
2. Go to System Settings and change WiFI settings: Proxy: Manual , Proxy hostname: Desktop IP address , Proxy port: 9000
3. Install and open Brave

Result will be the same as mentioned by @fmarier above

[kjozwiak]

Removed milestone, we'll move the issue into the appropriate milestone once we have uplifts. Assuming this needs to go out via the next possible release. It could be a 1.50.x if we end up getting another C112 build or 1.51.x which is the next major release as per https://github.com/brave/brave-browser/wiki/Brave-Release-Schedule#release-channel-dates. Either way, once we get uplifts, the issue will be moved into the appropriate milestone 👍

[stephendonner]

Verification PASSED using

Brave	1.52.84 Chromium: 113.0.5672.63 (Official Build) beta (x86_64)
Revision	0e1a4471d5ae5bf128b1bd8f4d627c8cbd55f70c-refs/branch-heads/5672@{#912}
OS	macOS Version 13.4 (Build 22F5059b)

Confirmed issue using 1.51.110

Steps:

1. entered sudo nano /etc/hosts in Terminal.app
2. added 127.0.0.1 redirector.brave.com and saved the changes
3. restarted macOS
4. installed 1.52.84
5. launched Fiddler Everywhere
6. launched Brave
7. checked for the two (2) initial, immediate GET requests to http://www.google.com/dl/release2/chrome_component...

Confirmed only requests to *.brave.com hosts during fallback, when redirector.brave.com is unreachable

1.52.84	google filter	1.51.110	etc/hosts

[taoeffect]

@stephendonner is it me or does the screenshot above show the two requests to google still in 1.51.110?

[stephendonner]

@stephendonner is it me or does the screenshot above show the two requests to google still in 1.51.110?

It is not you - the fix wasn't (yet) uplifted to 1.51.x, so that makes sense...

[fmarier]

@taoeffect The fix for the password manager leak (brave/brave-core#18153) is in 1.51, but the one for the fallback to http://www.google.com on port 80 will come a little later (1.52).

[MadhaviSeelam]

Verification PASSED using

Brave | 1.52.102 Chromium: 113.0.5672.126 (Official Build) beta (64-bit)
-- | --
Revision | c541687b21a73452ab403e2dced7033ddc97ee9d-refs/branch-heads/5672@{#1202}
OS | Windows 11 Version 22H2 (Build 22621.1702)

Confirmed issue using 1.51.118

Steps:

1. entered windows/system32/driver/etc/hosts
2. added 127.0.0.1 redirector.brave.com and saved the changes
3. restarted macOS
4. installed 1.52.102
5. launched Fiddler Everywhere
6. launched Brave
7. checked for the two (2) initial, immediate GET requests to http://www.google.com/dl/release2/chrome_component...

Confirmed only requests to *.brave.com hosts during fallback, when redirector.brave.com is unreachable

step 2	1.52.102	google filter	1.51.118

[Uni-verse]

Verified on Samsung Galaxy S21 5G using the following build version(s):

Brave	1.52.107 Chromium: 114.0.5735.26 (Official Build) beta (32-bit) 
Revision	7075cbb66f0542ac3e01ddfde6b813e7d61118a5-refs/branch-heads/5735@{#454}
OS	Android 13; Build/TP1A.220624.014; 33; REL

Using description and steps to reproduce in #29841 (comment), the fallback was reproduced using build version 1.50.106

The following rewrite rule in Charles Proxy was created to modify the http response code from 200 to 503 for all responses for https://redirector.brave.com

• Verified fallback to www.google.com:80 was not made if redirector.brave.com is unresponsive

1.50.x	1.52.x

[hffvld]

Verified on Galaxy Tab S8 using version(s):

Device/OS: SM-X700 Galaxy Tab S8 [gts8wifixx-user 13 TP1A.220624.014 release-keys]
Brave build: 1.52.109
Chromium: 114.0.5735.26 (Official Build) beta (64-bit)
Revision: 7075cbb66f0542ac3e01ddfde6b813e7d61118a5-refs/branch-heads/5735@{#454}

---

STEPS:

1. Enter sudo nano /etc/hosts in Terminal
2. Add 127.0.0.1 redirector.brave.com and saved the changes
3. Install build 1.52.109
4. Launch Charles Proxy
5. Launch Brave
6. Checked for the initial GET requests to http://www.google.com/dl/release2/chrome_component...

ACTUAL RESULTS:

• Verified that there is no http://www.google.com/dl/release2/chrome_component... GET calls observed

1.51.114	1.51.114	1.52.109	1.52.109

[btlechowski]

Reproduced on 1.51.118

Verification passed on

Brave	1.52.112 Chromium: 114.0.5735.35 (Official Build) (64-bit)
Revision	2295354895fa3652ae47b651481831484f16d1ff-refs/branch-heads/5735@{#713}
OS	Ubuntu 18.04 LTS

Verified fallback to www.google.com:80 was not made when redirector.brave.com is unresponsive