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englehardt

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Gmail's image proxying actually won't help much with this style of tracking. In the paper we found email addresses (or hashes of them) leaking to third parties via a query string parameter in the request URL. So the proxied URL still contains your email address and the third parties can still learn you opened and read the email. As another commenter mentions, we found these requests to occur the moment you first open the email in the Gmail web interface. Since the request URL is unique to you, it can still be used to serve you targeted content. See: https://web.archive.org/web/20170922213846/https://support.l...

Actually I suspect image proxying will also interfere with request blockers like ABP or uBlock Origin, which may have otherwise blocked all requests to that third-party domain.

We found that Apple Mail clients typically load remote resources by default, unless the message is spam. That content can't set or retrieve cookies, which is an improvement over other standalone clients.

I'd still recommend disabling remote content by default since the tracking identifiers (the hash of your email address, etc) are present in the image URL. That's enough to continue to track the read and serve targeted content. See: https://web.archive.org/web/20170922213846/https://support.l...

I prototyped this feature last year as an intern at Mozilla. I think the engineering done for containers can be exposed in a lot of cool ways to the user. I'd love for you to send in your ideas on the comment form [1]. One of the features we considered last summer was "site specific containers" [2], which would support your facebook example.

[1] https://docs.google.com/forms/d/1oQN14TUnqj-MDErp8MKxH_v7Ytt... [2] https://wiki.mozilla.org/Security/Contextual_Identity_Projec...

The Tor Browser folks have done some excellent work to reduce the fingerprintability of the browser. See "Specific Fingerprinting Defenses in the Tor Browser" here: https://www.torproject.org/projects/torbrowser/design/#finge....

For Firefox and Chrome there are canvas fingerprint blockers [1] and [2]. These are heuristic based, so you'll likely see a bit of false positives. uBlock Origin includes an option to prevent the leakage of local IP addresses [3].

[1] https://addons.mozilla.org/en-US/firefox/addon/canvasblocker...

[2]https://chrome.google.com/webstore/detail/canvasfingerprintb...

[3]https://github.com/gorhill/uBlock/wiki/Prevent-WebRTC-from-l...

Other co-author here. Unfortunately there are good performance reasons for allowing WebRTC to access the local IP, see the lengthy discussion here: https://bugzilla.mozilla.org/show_bug.cgi?id=959893. One use case is allowing two peers behind the same NAT to communicate directly without leaving the local network.

The working group recommendation that we linked in the paper (https://datatracker.ietf.org/doc/draft-ietf-rtcweb-ip-handli...) addresses some of the concerns that arise from that (namely the concern that a user behind a VPN or proxy will have their real, public address exposed), but still recommends that a single private IP address be returned by default and without user permission.

However that's still quite identifying for some network configurations, e.g. a network which assigns non-RFC1918 IPs to users behind a NAT. Seems to me that putting access to the local IP address behind a permission would both remove the tracking risk and still allow the performance gains after the user grants permission.