Cybersecurity firm Symantec (SYMC) - Get Report said that it was "highly likely" that a group of hackers working with North Korea is behind the WannaCry ransomware cyberattack earlier this month that infected 300,000 computers and temporarily shut down health services in the U.K. 

Symantec pointed out that the same Internet connection that installed the virus on two computers during the attack was also used during the 2014 cyberattack against Sony Pictures  (SNY) - Get Report , an attack that was also linked to North Korea. 

Earlier this week, North Korean officials continued to deny involvement in the attack, saying accusations against the country was part of "a dirty and despicable smear campaign."

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