Fonts blocking question

General discussion about the NoScript extension for Firefox
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randomnoscriptuser
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Joined: Wed Apr 10, 2019 1:25 pm

Fonts blocking question

Post by randomnoscriptuser » Wed Apr 10, 2019 1:33 pm

Hi,

I'm blocking fonts with Noscript in Firefox 66.0.2 but this site knows how many fonts are installed on my pc:

http://ip-check.info/?lang=en

In Tor Browser this site can't regonize how many fonts I actually have.
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:66.0) Gecko/20100101 Firefox/66.0

barbaz
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Re: Fonts blocking question

Post by barbaz » Wed Apr 10, 2019 1:50 pm

Moving to NoScript General.

NoScript's font blocking blocks REMOTE fonts, i.e. fonts that are downloaded from a web server and used 'on-the-fly'. It doesn't block fonts that are already on your computer; you've already decided you trust those fonts enough to install them system-wide, there's no security benefit to blocking them.
*Always* check the changelogs BEFORE updating that important software!
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Giorgio Maone
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Re: Fonts blocking question

Post by Giorgio Maone » Wed Apr 10, 2019 1:54 pm

randomnoscriptuser wrote:
Wed Apr 10, 2019 1:33 pm
In Tor Browser this site can't regonize how many fonts I actually have.
In facts, the Tor Browser prevents web pages from using any system-installed font except the most common 4 (one for each "family") from being used by any page, in order to make its users more difficult to tell apart.
However you need scripts in order to enumerate the local fonts.
This however has nothing to do with blocking remote typefaces, which is what the "font" permission does in NoScript.
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:67.0) Gecko/20100101 Firefox/67.0

randomnoscriptuser
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Joined: Wed Apr 10, 2019 1:25 pm

Re: Fonts blocking question

Post by randomnoscriptuser » Sat Apr 13, 2019 9:53 am

Oh, You're right, it seems I misunderstood this function :)

I have "regural" Firefox and Tor Browser (both with NoScript) and I got different results at ip-check.info. I thought that NoScript blocks pages from using system-installed fonts to avoid fingerprinting. Is there any way to do this with NoScript?
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:66.0) Gecko/20100101 Firefox/66.0

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Giorgio Maone
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Re: Fonts blocking question

Post by Giorgio Maone » Sat Apr 13, 2019 11:40 am

randomnoscriptuser wrote:
Sat Apr 13, 2019 9:53 am
Is there any way to do this with NoScript?
Other than disabling scripts, none.
Preventing the rendering engine from using local fonts requires forcibly "blinding" the browser about them: something which is in reach of a Firefox fork (like the Tor Browser) but not of an extension.
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:67.0) Gecko/20100101 Firefox/67.0

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