With Google all set to wage a war against online trackers, AdGuard, which develops a line of ad blocking and privacy protection browser extensions, has released a list of over six thousand CNAME-based web trackers.
CNAME (Canonical name) is a DNS record used to alias one domain name to another – so thanks to CNAME it’s possible to run multiple services from a single IP address. However, online advertisers and other unscrupulous agents abuse CNAME records to hide tracking scripts behind trusted domains.
“As content blocking has become widespread, most tools for excessive tracking proved to be fairly useless. But with the market moving more and more towards massive data collection, the tendency was to push it as far as possible. Some opt for a blatant approach, and some seek more inventive ways to collect users’ data,” noted AdGuard CEO Andrey Meshkov in a blog post as he shared the list of CNAME abusing trackers.
Arm yourself
Reportedly, one of the main reasons for the growing use of CNAME-based trackers is that there isn’t a law against using CNAME records deceptively.
However, user’s aren’t completely defenseless. Last year, the privacy-focussed Brave browser announced its ability to detect and block tracking cookies from cloaked CNAMEs. And Firefox users can protect themselves using third-party extensions such as uBlock Origin and AdGuard.
However, according to Meshkov Safari, Chromium, and Chromium-powered browsers like Google Chrome and Microsoft Edge, can’t yet examine DNS. This means they can only be effective against CNAME-based trackers using filter lists such as the one released by AdGuard.
“Thanks to our own DNS server, plus a set of standalone and browser-based content blocking tools, we’ve been able to hunt the hunters (or rather track the trackers), list them, and block them,” notes Meshkov adding that the company has shared the list on GitHub for other content blockers to use as well.
Via The Register