The National Police Agency said the two students in their early twenties were detained on December 9 when they met company officials in a Seoul hotel to receive money.
"They were arrested on charges of extortion and violating a law on the protection of industrial information," an investigator at the agency's Cyber Terror Response Centre told news agency AFP.
"The pair hacked the server of the company specialising in Internet networking and cyber security equipment to steal its business secrets," he said.
They had demanded about 800 million won ($683,760) from the company while threatening to sell its secrets to other people, he said. Further details were not given.