Security News > 2021 > March > AdGuard names 6,000+ web trackers that use CNAME chicanery: Feel free to feed them into your browser's filter

CNAME tracking is a way to configure DNS records to erase the distinction between code and assets from a publisher's domain and tracking scripts on that site that call a server on an advertiser's domain.

As privacy barriers have gone up to prevent marketers from gathering data from web users, CNAME manipulation has become more popular.

One reason for the growing popularity of CNAME tracking is that the deceptive use of its records can't currently be prevented - companies are free to configure their DNS records to disguise partners' servers as they see fit.

Since last October, the Brave browser can detect CNAME cloaking and will attempt to determine the cloaked domain to block its cookies if appropriate.

Firefox can do it too, with an extension like uBlock Origin or AdGuard DNS. Safari offers only a way to limit the lifespan of cookies set via CNAME abuse.

Resolve in Chrome, AdGuard is using its own DNS service to tease out whether domains are engaged in CNAME manipulation and has now made a list of those domains so they can be blocked by extensions and applications that integrate filtering lists.

News URL

https://go.theregister.com/feed/www.theregister.com/2021/03/04/adguard_cname_tracker/