The group of hackers identified as Armada Collective has threatened to launch a distributed denial-of-service (DDoS) attack on seven South Korean banks unless they pay the equivalent of $ 315,000 in bitcoins to No later than Monday, June 26.

South Korean authorities are in a "state of emergency" as the threats come just a month after WannaCry's famous global cyber attack which infected millions of computers in hundreds of countries, including South Korea, and whose security officials have linked since then, in the authorship, to North Korea.

South Korea has paid large sums of money in the past to hackers. Earlier this month, the web hosting group Nayana paid about $ 1 million to unlock more than 3,400 sites under its domain, which is believed to be the largest payment made in the area of ​​software extortion to date.

Choi Sang-Myung, a researcher at the Hauri cyber security group, believes that Nayana's payment may have prompted hackers to start a new misdeed, but said the country was well prepared.

Among the mercantile institutions at risk would be the main banks of the Asian country, KB Kookmin Bank, Shinhan Bank, Woori Bank, KEB Hana Bank, NH Bank. They are preparing several ways to prevent a possible DDoS attack by hackers, including blocking unnecessary IP addresses, dispersing traffic and implementing a "clean zone"

So-called "clean zones" are a defensive measure that seeks to undermine the effectiveness of DDoS attacks by directing malicious traffic away from the intended website. The redirect sends the content to a server that can handle the excessive flow of content.