Drawing an analogy from the lead-up to the Sept. 11, 2001 attacks, the former counter-terror head of the CIA said cyber has joined kinetic and bacteriological as the largest terror threats facing people today.

"Now it's your turn," Cofer Black, who currently chairs Total Intelligence Services, a subsidiary of private military firm Blackwater Worldwide, told a packed keynote hall Wednesday at the Black Hat conference in Las Vegas. "Things have changed."

He said last year's Stuxnet attacks certainly validated the threat. "This is huge," Black said, referencing the first-ever malware custom-built to attack industrial control systems.

But similar to the run-up to 9/11, even though he and his team were well aware of the possibility of an Al-Qaeda strike on the United States, not everyone appreciates the warning signs.

"Men's minds have difficulty adapting to things with which they have no experience," Black said.

And once an attack happens, he said chaos and confusion can be a "great inhibitor" to the proper response. Plus, many questions remain as to exactly what the response would entail. For example, could a cyberattack be met with a physical reaction.

"This is a very delicate window," he said.