The private information of an estimated 10.3 million users of online shopping mall Interpark has been stolen by a hacker group . The information includes names , addresses , email addresses , dates of birth and phone numbers . Police launched an investigation after learning about the massive data theft . The e - commerce company apologized Monday . " On July 11 , Interpark became aware that some of our user information had been stolen by a hacker group through an advanced persistent threat attack , and reported the hack to the police the next day , " said Interpark on its website . An advanced persistent threat ( APT ) attack is carried out on a compromised system over a long period of time without detection , instead of making a onetime hit . According to the National Police Agency 's Cyber Bureau , the attack began in early May . Interpark only became aware of this when the hackers demanded 3 billion won worth of Bitcoins , a cyber currency that is traded like hard cash . The company said highly sensitive information such as resident registration numbers and account passwords were not stolen . ;