Comcast leaks different bits of information in all sorts of ways. It would be relatively easy to combine the information they leak with public records to gain

Comcast leaks different bits of information in all sorts of ways. It would be relatively easy to combine the information they leak with public records to gain access to someone's account. This is just icing on the cake. You can identify addresses that are Comcast customers simply by going to their website and shopping for service. If you enter in the address of an existing customer, it tells you. You can cross reference this with open records like tax and voter registration to determine who lives their and potential phone numbers. You can confirm the owner of the account by using Comcast's bill pay without login feature. It allows you to specify a street address and telephone number to view/pay a bill. And based on the bill amount you might be able to determine which services they're subscribed to. If the person is renting equipment then they'll be broadcasting a hotspot that other customers can log into and use unless they're savvy enough to disable it. That could be used to determine their IP address. Those are just the ones I know about off the top of my head. I'm sure there are many more.