KCNA
South Korean lawmakers have recently come forward with the revelation that North Korean hackers gained access to Seoul's highly secured military intranet in September 2016 and made off with the US and South Korea's secret war plans.
"It's a ridiculous mistake," Rhee Cheol-hee, a South Korean lawmaker, told The Wall Street Journal.
North Korea personnel reportedly attacked a South Korean cybersecurity firm and embedded themselves in the software. South Korea's military used the software on its military computers, but the North Koreans still shouldn't have been able to get in because Seoul keeps its internet, or outwardly connected network, separate from its intranet, or private network.
But it only took one computer plugged into both the internet and intranet for the North Koreans to break in.
"They should have removed the connector jack immediately after maintenance work," said Rhee.
As a result, North Korea reportedly got ahold of OPLAN 5015, the US and South Korea's secret war plan to kill Kim Jong Un.
Since the hack took place, the US has repeatedly revised military options for dealing with North Korea, but the breach likely provided valuable intelligence for Pyongyang.