Please don't listen to the CEOs of Apple, Microsoft and Amazon. Listen to me. Tim Cook, Satya Nadella and Jeff Bezos are way smarter than me, but they want to sell you products and services cloaked as advice. You have profound technology problems but rather than buying more stuff and doing more things, you need to buy less and do the right things.
My advice to you:
1) 80/20 the federal computing landscape. Call for a 3 year mandate to reduce 80% of the footprint, with a focus on trashing customized software. The 20% that remains should be reinvigorated and refreshed and made available to all agencies. Accounts payable at DEA should be the exact same system as accounts payable at Homeland Security, the VA and Treasury.
2) Just say no and you'll need less protection! Security is a huge problem, because you have too many entry points and not enough guards. Reducing the footprint by 80% will dramatically reduce the unsecured entry points. Simple, standardized, vanilla systems are easier to protect.
3) Don't hire large consulting firms to guide strategy and then handle execution. In other words, don't let the big consulting firms write their own tickets!