Lotte Card, one of the nation’s major credit card companies, remained unaware for more than two weeks that it had been the target of a hacking incident.

According to a report from the Financial Supervisory Service(FSS) as submitted to the office of main opposition People Power Party(PPP) Rep. Kang Min-kuk on Tuesday, the first hacking attack took place at around 7:21 p.m. on August 14.

The hacking activity continued until August 15, leading to a leak of internal files. 

A subsequent attempt on August 16 was detected, but no additional data was compromised.
 
Lotte Card, however, only realized that a malignant code had gotten into its server on August 26, and verified there had been a hacking attack at noon on Sunday, 17 days after the initial attack.

The card company estimates that around one-point-seven gigabytes of data were leaked, and financial authorities are investigating the possibility that information regarding cardholders' online transaction request could also have been breached.

The FSS urged Lotte Card to operate a separate call center on the latest breach, reinforce monitoring of abnormal financial transactions, prepare full compensation measures in case of damage and to inform holders wishing to cancel or reissue their card of necessary procedures.

The FSS has also launched an on-site inspection, while working with the Financial Security Institute to verify whether cardholders' personal information had been breached.