Massive data theft hits 40% of South Koreans

The personal data of 20 million South Koreans - or 40 percent of the country's population - has been stolen, sparking outrage as worried consumers scramble to replace compromised credit cards.

The data was allegedly swiped by a worker at the Korea Credit Bureau, which offers risk management and detection services.

CNNMoney reports the worker, who had access to various databases at the firm, allegedly copied data onto an external drive during the course of a year and a half.

Clients of three Korean companies - KB Kookmin Bank, Lotte Card and Nonghyup Bank - were hardest hit by the data theft.

Read more from CNNMoney.