A South Korea lawmaker recently disclosed that hackers suspected to be North Korean 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," the lawmaker, Rhee Cheol-hee, told The Wall Street Journal.
North Korean 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 took only one computer plugged into both the internet and the intranet for the North Koreans to break in, The Journal reported.
"They should have removed the connector jack immediately after maintenance work," Rhee said.
As a result, North Korea reportedly got ahold of Operation Plan 5015, the US and South Korea's secret war plan to kill the North Korean leader Kim Jong Un.
Since the hack, the US has repeatedly revised military options for dealing with North Korea, but the breach most likely provided valuable intelligence for Pyongyang.
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