The hacker has been publishing internal information of the nuclear power company since December 15, including personal data for 10,000 company employees. The hacker has also released files containing maps, safety analysis materials and information on reactor cooling and conditioning systems of the Gori and Wolsong nuclear power plants.
On December 19, the hacker, who calls himself "president of anti-nuclear reactor group," demanded the shut down of both the company's Gori and Wolsong nuclear reactors. Messages from the hacker warned that if the Company does not close the reactors by December 25, he will "open to the world 100,000 pages of data that have not yet been revealed," according to Yonhap.
The Korea Hydro & Nuclear Power company stated that the leaked materials contain only general unclassified information and is not a threat to the security of the reactors.