Security News > 2021 > January > Firefox Cracks Down on Supercookies to Improve User Privacy
Mozilla this week announced further improvements to user privacy in Firefox, through the isolation of network connections and caches, thus essentially cracking down on supercookies.
Specifically, Firefox 85 is arriving with an updated network architecture, where network connections and caches are isolated to the website being visited.
"Trackers can abuse caches to create supercookies and can use connection identifiers to track users. But by isolating caches and network connections to the website they were created on, we make them useless for cross-site tracking," Mozilla says.
Firefox relies on cache to reduce overhead, sharing some internal resources between websites, such as images, and reusing a single network connection for the loading of resources that come from the same party, even if they are embedded on multiple websites.
"To prevent this possibility, Firefox 85 uses a different image cache for every website a user visits. That means we still load cached images when a user revisits the same site, but we don't share those caches across sites," Mozilla says.
To prevent trackers from abusing caches to create supercookies, Firefox 85 isolates a range of caches by the top-level site: Alt-Svc cache, DNS cache, font cache, favicon cache, HSTS cache, HTTP Authentication cache, HTTP cache, image cache, OCSP cache, style sheet cache, and TLS certificate cache.