Police have begun a pre-indictment investigation into hacking incidents that occurred in succession at Daishin Securities, Mirae Asset Global Investments and digital asset exchange Bithumb, among others.

The National Police Agency said on Oct. 28 that its National Office of Investigation started the pre-indictment investigation earlier on Wednesday into hacking cases at securities firms and digital asset exchanges. The probe is being handled by the same investigation team that has been investigating a series of hacks in the financial sector.

Daishin Securities recently identified a leak of personal and credit information on 38,490 customers. Bithumb has so far been reported to have suffered a leak of employee information and is additionally checking whether member information was included.

Mirae Asset Global Investments said information related to some internal work systems was leaked, but no leak of personal credit information or financial loss has been confirmed so far.

Earlier, the financial sector also suffered hacking damage at 16 financial companies including KB Kookmin Bank, as well as banks, savings banks and capital companies. About 100,000 cases of personal information, including resident registration numbers, account numbers and addresses, were leaked, and police have been investigating the cases.

Police plan to compare the attack methods used in the earlier financial-sector hacking cases with those used in the securities and digital asset industry hacks to see whether the same attacker was involved.

A police official said, "We are not ruling out the possibility that the attack was carried out by the same person as in the bank hacking case."