Apr 11, 2011 10:04 GMT  ·  By

South Korea's Financial Supervisory Service (FSS) has launched an investigation into a data breach at Hyundai Capital, the country's biggest lender, which affected around 420,000 consumers.

The security incident was disclosed last week, when Hyundai Capital announced that a hacker managed to steal the names and home addresses of over twenty percent of its clients.

Company officials said no financial information was exposed, although they were unsure if telephone numbers and e-mail addresses were also compromised.

"There is a chance more customer information may have been hacked. There's also a possibility the account numbers and passwords of 13,000 prime loan pass users may have been stolen," the company said in a statement.

As a precaution, on Friday Hyundai asked two million customers to change their passwords, which prompted FSS to launch an official probe.

"The investigation is focusing on whether Hyundai Capital encoded its customers' passwords for enhanced security," the Financial Supervisory Service said, according to the Yonhap news agency.

"If results show that the passwords weren't encoded, Hyundai Capital may receive penalties for violating regulations on electronic finance," the country's financial regulator added.

Hyundai Capital is the country's biggest provider of personal loans, home mortgages and auto financing services. The breach has prompted fears that other financial companies might face similar security problems.

The FSS is considering expanding its investigation in order to cover other firms, some of which have already started tightening their security in case they might also be targeted.

Officials from Hana Bank, Industrial Bank of Korea and Shinhan Bank, confirmed that additional measures are being taken and that policies are being reviewed in order to prevent hackers from breaking into their systems. So far, no other intrusion has been reported.