Open Bug 1610762 Opened 1 year ago Updated 1 year ago

privacy.resistFingerprinting useragent OS spoofing breaks Netflix logged out video playback on Linux

Categories

(Core :: Audio/Video: Playback, defect, P5)

66 Branch
Unspecified
Linux
defect

Tracking

()

People

(Reporter: ke5trel, Unassigned)

References

(Blocks 1 open bug, Regression)

Details

(Keywords: regression)

STR:

  1. On Ubuntu 19.10, start Firefox with privacy.resistFingerprinting enabled.
  2. Go to the Netflix test pattern (no account required). EDIT: Must be logged out.
  3. Enable DRM, wait for it to install.
  4. Play video.

Black screen with no video playback.

Useragent before regression: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Useragent after regression: Mozilla/5.0 (Windows NT 6.1; rv:60.0) Gecko/20100101 Firefox/60.0

Workaround is to install an extension that allows changing the useragent to Linux.

Regression range:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=8e746f670f430ceb0cb85fa8eebfe97cbe42ff01&tochange=ed68c008e5d8db0940a1fbc31bfc24efccba6c26

Regressed by Bug 1509829.

Useragent before regression: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Useragent after regression: Mozilla/5.0 (Windows NT 6.1; rv:60.0) Gecko/20100101 Firefox/60.0

This looks strange, I think it's outdated. With Firefox >= 68 you should get
Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Firefox/68.0.

Netflix mentions on their help page [1] that they require Firefox >= 65, which is of course greater than the version number in your user agent. I also did a quick test with Firefox 72 (from Arch Linux, not the official Mozilla build) and it works for me.

[1] https://help.netflix.com/en/node/23742

Those useragents are immediately before and after the regression on 2019-02-28 when Firefox 60 was the ESR. Video playback works with that Nightly build while reporting as Firefox 60 as long as the OS is reported as Linux.

Current useragent with RFP on 72 and Nightly 74 (official Mozilla builds) is Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Firefox/68.0 and video playback does not work unless the reported OS is changed to Linux.

Browser Console output with RFP spoofed useragent:

navigator.requestMediaKeySystemAccess promise rejected 0x80530009 'Key system is unsupported'

Okay, now I can reproduce this bug with a fresh profile and Firefox 72 (official Mozilla build). But when I log in, I can play videos. Have you tried with an account?

Just tried it with an account and it works so this appears to be limited to videos accessible when logged out which is not many, the test pattern is the only one I can find publicly indexed. The video player seems to be the same version when logged in and out (cadmium-playercore-6.0020.327.051.js) but the user interface is arranged differently when logged out suggesting a different treatment.

Component: DOM: Security → Audio/Video: Playback
Summary: privacy.resistFingerprinting useragent OS spoofing breaks Netflix video playback on Linux → privacy.resistFingerprinting useragent OS spoofing breaks Netflix logged out video playback on Linux

Tom, do we have a policy around resist fingerprinting and bustages such as this?

Flags: needinfo?(tom)

(In reply to Bryce Seager van Dyk (:bryce) from comment #5)

Tom, do we have a policy around resist fingerprinting and bustages such as this?

We keep them open to track them, but most we don't really have any real expectation of being able to fix or find a way to mitigate. If you want to assign it out of your Component; that's fine.

Flags: needinfo?(tom)
Priority: -- → P5
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