There was an interesting twist to the recent distributed denial-of-service (DDoS) attack against domain name provider Dyn that plunged huge areas of North America and Europe into internet darkness.

The perpetrators didn’t directly attack the servers of their ultimate target. Instead, they compromised 100,000 small, interconnected devices with weak default passwords, building an enormous botnet that then battered the real target. In doing so, these attackers make the case for secure by design.