A former temporary worker dispatched to a unit of Nippon Telegraph and Telephone (NTT) West, illegally leaked some 9 million sets of customer information, reports The Japan Times, citing the unit and another subsidiary of the telecommunications company. The leaked information included addresses, names and phone numbers. Credit card information was included in 81 cases, according to the two NTT West units, NTT Business Solutions and NTT Marketing Act ProCX, both based in Osaka, Japan.

The former temporary employee worked for NTT Business Solutions from June 2008 to July this year, engaged in the maintenance and management of a call centre system server in which customer information and other data were stored and holding the right of free access to the server and downloading data. The former worker illegally downloaded customer information around July 2013 to January this year and had some of the data handed over to a list broker, the NTT West units said.

An investigation conducted after a client pointed to the possibility of information leakage in April 2022 failed to detect the leakage, which came to light after police in July launched a probe into the former worker on suspicion of violating the unfair competition prevention law.

In response to the discovery of the data leakages, NTT Marketing Act ProCX has changed specifications to require multiple administrators to check downloads from maintenance computers and introduced a system that can quickly detect when work that carries a security risk has been done. "We deeply apologize for causing (our customers) great concern and trouble," Akiko Murobayashi, president of NTT Marketing Act ProCX, told a news conference in Osaka.