U.S. government says North Korea was behind WannaCry cyberattack and ransomware

The U.S. government has named North Korea as the source of the devastating WannaCry cyberattack.

In a Wall Street Journal op-ed Monday, Thomas Bossert, Trump's homeland security assistant, wrote that North Korea is "directly responsible" for the attack that "was widespread and cost billions."

WannaCry was a ransomware program, partially based that spread on Windows-based computers of numerous individuals and institutions in multiple countries in May this year. After infecting a system, the malicious software would encrypt the users' files and asked for a payment of roughly $300 worth of Bitcoin. In many cases, even paying the ransom did not decrypt the files.

Back in June, several security researchers pointed out that WannaCry might have originated in North Korea based on code samples of the software, which matched another malicious software previously traced to a hacker group in North Korea. Bossert now says the evidence is conclusive.

"We do not make this allegation lightly. It is based on evidence. We are not alone with our findings, either. Other governments and private companies agree. The United Kingdom attributes the attack to North Korea, and Microsoft traced the attack to cyber affiliates of the North Korean government," he wrote.

Bossert did not lay out the exact measures the U.S. government plans to take against North Korea, but he did write that the U.S. "will continue to use our maximum pressure strategy to curb Pyongyang’s ability to mount attacks, cyber or otherwise."

During a conference call with the press Tuesday, Bossert said several countries, including Australia, Japan, New Zealand and the UK, have reviewed the evidence provided by the U.S. and have joined the U.S. in denouncing North Korea for being behind this attack.

Bossert also praised Microsoft and Facebook for taking action last week to "disrupt the activities of North Korean hackers."

Answering a question from a journalist, he pointed out that it's the North Korean government, and not some rogue hackers, that's behind the attack. He also said the intent behind the attack was to cause "destruction" and not monetary gain.

He also said he does not believe the U.S. government acted too slowly in calling out North Korea. "It's better to get it right than to get it fast," he said.

Bossert also defended the U.S. government's practice of sometimes keeping software exploits for itself and even working on its own exploits and implementing them in real scenarios. According to him, this allows the U.S. government to find and track bad actors as well as warn major targets before they're attacked.

U.S. President Donald Trump has called out North Korea and the country's leader Kim Jong-un numerous times for performing nuclear and missile tests and threatened to "destroy" the country if it continues to do so.

UPDATE: Dec. 19, 2017, 3:19 p.m. CET The article has been updated with Bossert's comments from the media conference Tuesday.