South Koreans seethe, sue as credit card details swiped

The theft of personal information from more than 100 million South Korean credit cards and accounts, reportedly including those of President Park Geun-hye and UN chief Ban Ki-moon, has ignited a storm of anger and litigation against credit firms.

Worried Koreans on Tuesday packed into branches of one of the banks hit by the theft to ensure their money was safe, while lawyers said 130 people joined a class action suit against their credit card providers in what is expected to be the first of multiple litigations.

"Of course I'm angry. Anyone might know when I pay my credit card bills, let alone my phone number and where I live. I might as well keep all my money in my closet," said one card user, Lee Young-hye, outside a bank branch.

The biggest breach of personal privacy ever in South Korea has further highlighted the vulnerability of credit card information after tens of millions of US cardholders' details were stolen from retailer Target Corp during the holiday shopping season.

South Koreans on average have more than four credit cards, something that has contributed to one of the highest levels of personal debt relative to the size of the economy in the developed world.

The data security breach affected around 15 million cardholders, according to official estimates, by far the largest in a series of such scams against financial firms in South Korea going back to 2011. Some previous attacks involved hackers believed to originate from North Korea, but this one seems to have been an inside job.

Financial regulators said a contractor with the Korea Credit Bureau, a private firm that manages the credit information of millions of Koreans for financial services providers, simply loaded details of 105.8 million accounts held by KB Kookmin Card Co Ltd, Lotte Card Co Ltd and NH Nonghyup Card onto a portable hard drive.

The technician was allegedly working on forgery-proofing credit cards when he committed the theft in February, June and December last year, according to regulator Financial Supervisory Service (FSS), citing the prosecutor's office leading the investigation.

The man then sold the information to at least two people including a loan marketer and a broker, the FSS said. The contractor and at least one other person have been arrested.