"2. "all he requires to perpetrate the hack is the target pump's
serial number."
Do we know how much entropy is in those? They could very
well be sequential or date derived.
As you can clearly see, I am objecting to the apparent assertion that requiring the serial number should be considered a mitigating factor if we don't know anything about the entropy of these serial numbers. Without additional information, we should not be comforted by this.Allow me to be perfectly blunt to get across my point once and for all: I don't give a shit about insulin. I don't give a shit about insulin pumps. I care misconceptions about security, and improper security implementation. This article serves as nothing to me other than a vehicle to discuss these things.
Most importantly: I am more concerned with your apparent suggestion that "a serial number is probably a sufficient shared secret" than I am with anything in the story. Serial numbers, as a general rule, make terrible shared secrets.