There are few limits to the destruction that could be caused by a devastating cyberattack, retired Adm. Michael Rogers told CNBC in one of his first interviews after departing the National Security Agency five months ago.

"There is no scenario that is beyond the pale of possibility in the world we are living in now," said Rogers, who oversaw the NSA for nearly four years. "The only limit, in many ways, is what is the objective of the attacker, and what's the vector that they try to use to achieve the objective. Don't just fixate on one or two things."

Rogers said that during his tenure, the agency focused its concerns on the financial sector.

"It's all about trust. It's about the ability to sustain these literally millions of global transactions simultaneously with the idea that at any one second I have perfect knowledge of money, who has it, how much, who has it, what are the flows," he said in the interview Monday.

Rogers cited the North Korean attack against Sony Pictures Entertainment in 2014 and the NotPetya global ransomware attack of 2017 as two that particularly concerned him.

The Sony attack had particularly strong implications because it was the first time a president talked about cybersecurity and called out a state actor.