PureBrowser's user agent string is too uncommon and as such is a privacy concern

PureBrowser is very uncommon and it has a very uncommon user agent string. Uncommon user agent strings can be used to fingerprint a user, so it is a privacy concern.

I suggest changing it to something common, like the Tor project does:
Mozilla/5.0 (Windows NT 6.1; rv:60.0) Gecko/20100101 Firefox/60.0

Additionally, this fixes another problem where users cannot install extensions from https://addons.mozilla.org/ because Mozilla doesn’t recognize the browser as Firefox.

Firefox also comes with privacy.resistFingerprinting option in about:config, which automatically changes the user agent in addition to a bunch of other tweaks to resist fingerprinting.

This can possibly break some websites, so it may not be the best solution, but it is worth considering so I will mention it anyway.


Just note that Firefox only launches as a window, not maximized, when set to ‘true’. I found out the hard way.

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Yes, that is intentional. It is possible to fingerprint the user via his screen resolution, which can be done when browser is maximized.

privacy.resistFingerprinting works around that by starting in a windowed mode.


That is for this reason it’s recommended to change the user agent string to a value similar to what you suggest on PureOS tracker wiki:

Setting the OS to Windows 7 instead of Linux as you do means preferring privacy a bit more than usability, for the occasional uses of it.

That said, the privacy concerns have already mentioned in PureOS tracker Task 247: https://tracker.pureos.net/T247
In the task description there is a link to Panopticlick https://panopticlick.eff.org/ which demonstrates how many other browser settings may be used for fingerprinting. I ran it and my particular setup could be fingerprinted much more because of the HTTP_ACCEPT headers (partially dependent of the preferred languages settings), the screen resolution and color depth and the system fonts set than of the user agent string.

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