Many individuals and many organizations treat their router and WiFi network as a security perimeter. “The hostile world is outside. The warm, friendly, safe world is here, on our side of the fence.” The result is relaxed security inside the fence—printers anyone can talk to, media players with no passwords, open file sharing. Not to mention all the insecure IoT devices that may be on their network. The new KRACK Wifi exploit allows attackers to blow past Wifi’s built-in security.