A hacking network dubbed Onion Dog that targeted transportation and other sites in the Republic of Korea and the Democratic People's Republic of Korea has been broken, a leading Chinese security software provider announced on Wednesday.

The group, which had operated in cyberspace for three years, made use of loopholes in office software to steal online information in both countries, according to a report by 360 SkyEye Labs, an institute that researches security loopholes under Qihoo 360, the security software pioneer.

The group's first attack dated back to October 2013, the report said, adding that it targeted shipping, harbor, subway and bus networks in the two countries last year, and hit electronic and water resource enterprises in 2014, the report said.

It was not immediately known how authorities responded to Qihoo 360's information.