Korea remains on alert for the ransomware attack called WannaCry that has hit more than 230,000 computers in 150 countries since Friday.
As of Monday evening, a total of eight companies, including Korea's top theatre chain, and thousands of Internet Protocol addresses were reported to have been infected. No government organisations were found to have been hit by the attack yet.
"The figure (for the infections) is expected to rise as the week begins. We need thorough measures to prevent further damages on growing concerns about the spread of ransomware," said Yoon Young-chan, chief presidential secretary for public relations, during a briefing Monday.
"The government raised the nation's alert level on cyber crisis from attention to warning on Sunday evening in response to the ransomware attack that had caused damage across the globe," Yoon added.