It was at the Securedrop website. How did I end up there ? I read something about Sequoia and encryption and then wanted to see what Securedrop entailed.
Meanwhile I’ve raised the security settings. Still, today someone in this community (?) mentioned that Tor browser does not protect the remote to check for the OS, and now this. Color me surprised.
That can’t have been the reason, rather the fact it could tell.
Your browser sends information about its version and the os in the useragent string. It is supposed to lie and say it is a very commonly used useragent, specifically for purposes of fingerprinting. That would be windows, default configuration, firefox version something not you firefox version
The underlying OS will be detected regardless of the useragent.
That would be a fail of the fingerprinting protection. A properly set up TOR browser for example should not allow that detection by any means. If you know how to detect it, please report it as a critical vulnerability.
I could think of maybe some edge case behavior in webrenderer or js cavas etc., which would mainly expose info on the specific browser and underlying hardware, but that is all of course blocked of or fixed in hardened browsers.
Further, if you have a reliable method, you could sell it off to for example Netflix, who are trying to block higher resolutions for Linux browsers but are currently foiled by changing the useragent (if you have widevine set up).