North Korean hackers targeted a popular security software South Koreans use for financial transactions in what may have been part of preparations for a nationwide cyberattack, police announced on Tuesday.

The Korea National Police Agency (KNPA) said in a press release that it had “preemptively” discovered the cyberattack on INISAFE and prevented the “danger of being expanded” further.

“There is a possibility that North Korea had been preparing for a large-scale cyberattack [against South Korea] using the vulnerabilities of the finance and banking security certificate software, which is installed on over 10 million computers nationwide,” it