Security researchers at UC San Diego and Stanford have discovered four new ways to expose Internet users’ browsing histories. These techniques could be used by hackers to learn which websites users have visited as they surf the web.

The techniques fall into the category of “history sniffing” attacks, a concept dating back to the early 2000s. But the attacks demonstrated by the researchers at the 2018 USENIX Workshop on Offensive Technologies (WOOT) in Baltimore can profile or ‘fingerprint’ a user’s online activity in a matter of seconds, and work across recent versions of major web browsers.