CNAME-based tracking

yellowzip2 · n00b Joined: 20 Feb 2021 Posts: 13

I finally switched from ungoogled-chromium (pf4public overlay) to Firefox (with the usual privacy tweaks) recently in part prompted by claims made recently about CNAME deception.

CNAME tracking abuses DNS records to erase the distinction between first-party and third-party contexts. Firefox running the uBlock Origin 1.25+ extension can see through CNAME deception whereas Chromium based projects running uBlock Origin may not.

Has anyone here been following developments with CNAME-based tracking with regard to browser choice?

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

Thanks for the heads up. I hadn't seen that one.

I find it sad that Firefox seems to be the least worst option. I've never used Chrome for personal use, and only briefly tried Chromium.
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yellowzip2 · n00b Joined: 20 Feb 2021 Posts: 13

pa4wdh · l33t Joined: 16 Dec 2005 Posts: 812

It's indeed one of the bad signs of the state to today's internet: "Gee, users don't want to be tracked and are blocking us, lets try an other way so they can't block us".

It's not a browser based solution, but my way of working seems to work against this kind of tracking as well. I'm user BIND to do DNS based blocking. I create zones for domains i wish to block and insert a wildcard in there which directs the requist to my own webserver (which answers with a 404

).

For example, i have blocked doubleclick.net, so any request for anything within that domain is redirected. Now lets assume they start using cname based tracking under tracker.example.com. Now tracker.example.com will resolve into <something>.doubleclick.net, and from there it's again redirected to my own system.

I haven't actually ran into cname based tracking yet, so this is all theory. Any other insights or comments are welcome

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figueroa · Posted: Sun Feb 28, 2021 3:56 am Post subject:

One of my tools is I have over 60,000 entries sent to 0.0.0.0 in /etc/hosts. 191 of them are doubleclick.net entries.
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yellowzip2 · n00b Joined: 20 Feb 2021 Posts: 13

figueroa · Posted: Sun Feb 28, 2021 4:02 pm Post subject:

See my posts in the following forum page regarding my two scripts to curate your own /etc/hosts additions.
https://forums.gentoo.org/viewtopic-t-1107432-highlight-hosts.html

Don't stop at the first post. I continued to share improvements which I continue to use, shared in the last post of that thread, on the second page.
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i7-2600 @ 3.40GHz; 16 gb; Radeon HD 7570
amd64/23.0/split-usr/desktop (stable), OpenRC, -systemd -pulseaudio -uefi

Zucca · Posted: Sun Feb 28, 2021 5:37 pm Post subject: someonewhocares

I've been using https://someonewhocares.org/hosts/ as my source for domains to block.

Although I try to keep my /etc/hosts clean so I pass the block list hosts -file for my dns as an additional hosts -file.
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figueroa · Posted: Sun Feb 28, 2021 6:20 pm Post subject: Re: someonewhocares

Zucca · Posted: Sun Feb 28, 2021 9:21 pm Post subject:

Using dnsmasq:

Zucca · Posted: Sun Feb 28, 2021 9:25 pm Post subject:

BTW... There is a project which merges several bad host lists from the net to a single one: https://github.com/Ultimate-Hosts-Blacklist/Ultimate.Hosts.Blacklist
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figueroa · Posted: Mon Mar 01, 2021 3:00 am Post subject:

figueroa · Posted: Mon Mar 01, 2021 3:13 am Post subject:

Zucca · Posted: Mon Mar 01, 2021 7:36 am Post subject:

I found it while searching for the someonewhocares -site.
I think I could give it a try. My current hostlist already block smart TV commercials quite well, but some still get past it.
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pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

Since the discussion of blocking hosts has expanded, it seems worth noting that it isn't a useful defense against the CNAME issue mentioned in the article.
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yellowzip2 · n00b Joined: 20 Feb 2021 Posts: 13

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

I'm no fan of Apple, but this was notable:

yellowzip2 · n00b Joined: 20 Feb 2021 Posts: 13

AdGuard : cname-trackers - in case you're not using : Ublock-Origin.

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

I have Origin installed, but I don't understand how to use it. It doesn't seem to block as much as I would prefer. I still rely on uMatrix (I'm aware it has been abandoned).

While I'm not worried about those two extensions, I have always considered extensions a "concern."

Then along came...

https://krebsonsecurity.com/2021/03/is-your-browser-extension-a-botnet-backdoor/
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yellowzip2 · n00b Joined: 20 Feb 2021 Posts: 13

yellowzip2 · n00b Joined: 20 Feb 2021 Posts: 13

Hu · Moderator Joined: 06 Mar 2007 Posts: 21633

Browser extensions have always had this problem. The scope of access is so coarse that most extensions that intend to be broadly useful end up empowered to cause tremendous havoc if abused. Mozilla killed XUL extensions in part with the claim that the new permissions-based model would be so much better, because extensions would be required to declare what they wanted and users could review it. In practice, the permission scopes are too broad to be useful, and the Firefox user base fragmented. Some people refused to upgrade to XUL-free versions. Some fled to a variety of forks, many of which have as their main claim to fame that XUL-extensions still work.

alamahant · Advocate Joined: 23 Mar 2019 Posts: 3879

Will having such a massive hosts file somehow impact web browsing speed or performance?
Thanks a lot
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figueroa · Posted: Thu Mar 18, 2021 4:55 pm Post subject:

Tony0945 · Posted: Thu Mar 18, 2021 5:02 pm Post subject: