Look, you don't know what DDOS is, its gonna take a lot of research and resources to do anything that would impact any large corp, no less a guberment.
Step 1 get lots of computers and lots of friends or bots.
Step 2 ping (not really) whoever you want to ddos with all the bots and pcs.
You'd be surprised as what buildings are data centers. They usually look like a warehouse. There's several all over the place. I would guess at least 5 in each major city, Sacramento, SF, LA, and so on.
But be careful of a super boil heating or whatever the term is. You boil water in the microwave and it doesn't bubble, once you break the tension it all boils at once.
Physicists get jobs everywhere. They require lots of math, but other info too.
Not really an answer as I don't know any specific math majors other than teaching?