Modified clients are definitely possible - review the recent Project Zero research into webRTC vulnerabilities, which included a look at FaceTime and discovered

Modified clients are definitely possible - review the recent Project Zero research into webRTC vulnerabilities, which included a look at FaceTime and discovered several exploitable bugs https://googleprojectzero.blogspot.com/2018/12/adventures-in-video-conferencing-part-2.html https://googleprojectzero.blogspot.com/2018/12/adventures-in...