Privacybadger: With 3p Cookies blocked in Chrome, JS SetCookie events seem to be detected but don't cause blocking

[pde]

(As discussed on Mattermost). I think I the issue I was observing with lots of unblocked trackers on pages like Chicago Tribune articles was several different issues at once. In addition to circumvention of content blocking by that page, it seems that when third party cookies are blocked in Chrome, PB notices the set cookie events but doesn't actually red/yellow list because of them?

[svandragt]

This started happening since the latest update as it used to work before the 2018.1.30 version (Vivaldi)

[ghostwords]

Hi @svandragt, could you describe how you noticed this issue?

[svandragt]

@ghostwords I'm now wondering if instead Privacy Badger crashed? Instead of a badge with the number of blocked requests, and a list of domains and their status, I saw the following:

I just happened again here on GitHub. Re-enabling the extension and reloading fixed it so I now don't thinkit's 3p cookies related, I just turned Block third party cookie back on.

It's possibly related to #1240 however privacy badger works fine and then starts failing.

When I inspect the background page from the extensions list:

[ghostwords]

@svandragt Looks like another Vivaldi user is experiencing the same issue: #1855.

[pdbits]

@ghostwords Facing the same issue, even with the same error in console, but reloading/reinstalling doesn't fix the issue.

[svandragt]

I'll move my discussion to #1855 as I did only notice it after Vivaldi updating as well.

[ghostwords]

@pde Privacy Badger is indeed affected when third-party cookies are disabled, as Chrome seems to block writing of cookies and localStorage by third parties. Privacy Badger still gets to learn from Set-Cookie headers sent by third parties, however.

I am not sure there is anything to do here other than to update the FAQ entry for what happens when you disable third-party cookies.

[ghostwords]

We should investigate what the Privacy Badger experience is like with third-party cookies disabled, see whether we can do anything to improve it (such as perhaps detect failed JavaScript cookie events), and document the differences using Badger with and without third-party cookies.

[ghostwords]

FAQ entry updated: https://github.com/EFForg/privacybadger/wiki/Home/_compare/0c3cb962825dd2577304a71dae6d8da7ae87a3fe...a4503008e228da461614ecc2bd09e381c3c4c46a

[ghostwords]

This answer now lives on the homepage FAQ: https://www.eff.org/privacybadger/faq#Does-Privacy-Badger-still-work-when-blocking-third-party-cookies-in-the-browser