America's greatest vulnerability is its continued inability to acknowledge the extent of its adversaries' capabilities when it comes to cyber threats, says Ian Bremmer, founder and president of leading political risk firm Eurasia Group.

Speaking to CNBC from the Munich Security Conference on Saturday, the prominent American political scientist emphasized that there should be much more government-level concern and urgency over cyber risk. The adversarial states in question are what U.S. intelligence agencies call the "big four": Russia, China, North Korea, and Iran.

"We're vulnerable because we continue to underestimate the capabilities in those countries. WannaCry, from North Korea — no one in the U.S. cybersecurity services believed the North Koreans could actually do that," Bremmer described, naming the ransomware virus that crippled more than 200,000 computer systems across 150 countries in May of 2017.

He also noted the NotPetya malware attack in July 2017, considered the costliest cyberattack in history, which U.S. and European governments have accused Russia's military of implementing. Believed to be a deliberate attack on Ukraine, it actually wiped off half a point from Ukraine's gross domestic product.

Borge Brende, president of the World Economic Forum, weighed in, stressing the economic cost of cyber crimes. "It is very hard to attribute cyberattacks to different actors or countries, but the cost is just unbelievable. Annually more than a thousand billion U.S. dollars are lost for companies or countries due to these attacks and our economy is more and more based on internet and data."