Police have arrested two persons in South Korea for allegedly stealing personal details of about 8 million mobile phone subscribers and then selling the same information to marketing companies.

The case is one of the Asian country’s largest hacking scandals ever. The investigators said that the two men developed the hacking program and used it to steal names, residential registration numbers and phone numbers of customers of the country’s largest fixed-line telephone company and second largest mobile operator, KT.

They successfully uploaded the program onto the company’s system and it gathered information for months. According to estimates from the police, the two men made about $877,000 from the hacking procedure. The two persons then sold the program as well as the information collected by them to telemarketing companies that used the data to convince customers to switch networks.

The hacking scandal went on for a period of five months from February and affected about 8.7 million of the telecom service provider’s 16 million mobile customers. KT has already apologized to the users and have said that it will improve the security around its systems.