Many fraudulent transfers involving bank account breaches and NTT Docomo Inc.'s e-money payment service occurred over several days in early September, The Yomiuri Shimbun learned Thursday.
Police believe the illegal transfers from accounts of bank customers were conducted by a cybercrime ring, which obtained the victims' bank account numbers and other information to open Docomo e-money accounts, according to sources close to the investigation.
The police are investigating the case on suspicion of computer fraud and other crimes, they said.
NTT Docomo said it received two reports of bank account breaches from 77 Bank in Sendai on Sept. 3, followed by similar reports from Ogaki Kyoritsu Bank in Gifu Prefecture and Chugoku Bank in Okayama City.
The major mobile phone carrier announced the following day it had suspended new registrations for the e-money payment service at the three banks.
The police have since Monday been receiving notifications from other banks of further account breaches related to the service.
Shiga Bank in Otsu reported that illegal transfers were made on Sunday from seven customer accounts, and Tottori Bank in Tottori City also confirmed illegal transfers of this kind from three accounts, the sources said.
The police believe that the crimes were carried out intensively around this time.
Most of the illegal transfers were conducted shortly after the hackers linked the victims' bank accounts with NTT Docomo accounts, which were opened under the guise of the account holders. Many of the transfers were made for amounts approaching the monthly limit of 300,000, yen the sources said.
According to 77 Bank, there has been no evidence of unauthorized access to the bank's core system. Police officials do not believe the banks were hit by cyber-attacks, but rather that account holders' information and PINs could have been stolen through phishing using a fake website.
NTT Docomo had confirmed 66 cases totaling about 18 million yen in damage as of Thursday noon at a press conference Friday.
The Financial Services Agency has instructed the banks and NTT Docomo to take all possible measures for the victims, Deputy Chief Cabinet Secretary Akihiro Nishimura at a press conference Thursday.
"We'd like to take appropriate measures to ensure that users are protected," Nishimura said.
NTT Docomo will enter discussions with the banks on compensating customers for the entire amount of their loss, the firm said Thursday.
When similar bank account breaches using NTT Docomo's e-money service were confirmed at Resona Bank in May last year, the firm also compensated the victims for the entire amount of their loss.
Read more from The Japan News at https://japannews.yomiuri.co.jp/
