Bruggling is a term derived from the word smuggling and browser that describes a technique for data exfiltration using browser bookmark synchronization.

The technique provides attackers with a way to use bookmarks to exfiltrate data from an organization or install attack tools or payloads onto devices by taking advantage of bookmark synchronization. It gives attackers a way to bypass most host and network-based detection tools.

It takes advantage of the fact that modern browsers are able to store a large volume of characters into bookmarks. It has been demonstrated that some browsers can store the entire contents of the book “Brave New World” using just 2 bookmarks.