Lately, ad blocking community has been agitated about the so-called hidden trackers problem. For example, uBlock Origin's GitHub page has become a platform for a rather intense discussion among developers. We'll explain what it all is about.
Some trackers (such as Criteo) claim to be impossible to detect as a third-party one, using this as an advertising point to their customers. You may ask, why does it matter so much? That's because ad blockers generally don't touch first-party trackers, otherwise it's fraught with all kinds of complications. And first-party tracking is rather harmless in most cases anyway.
So how does it work? It's quite simple, honestly:
A client adds their domain
This domain is then redirected to tracker's domain using DNS
Browser extensions can't see DNS redirects, so extension-based ad blockers have no idea that this domain is, in fact, a third-party one.
AdGuard DNS will block such disguised trackers. On DNS level, it's trivial to figure that a domain is actually a disguised tracker.
This way we'll be able to find all these disguised tracking domains and promptly build a database that will be added to the AdGuard Tracking Protection filter list.
Other filter lists (like EasyPrivacy, Ghostery etc) hopefully will be able to pick it up from there.
Additionally, all AdGuard products that support DNS filtering (AG for Android, AG for iOS, AG Home) will be naturally immune to this kind of tracking. Provided, of course, you have AdGuard DNS up. We plan to add DNS filtering to our other products (AG for Windows and AG for Mac) in the near future as well.
The beauty of this solution is that it's not limited to any browser or even a single product, and in the end will help everyone.
This whole situation once again proved that the power of ad blocking community is in its ability to come together when its really needed and come up with a solution that will benefit us all — and that means you, a customer, too.
UPD: AdGuard DNS has already started to block these cloaked trackers.