Bank of Yokohama: it emailed a spreadsheet holding data on 41,729 customers to an advertising contractor by mistake, twice

1. 2021-01-08

   The bank emailed a spreadsheet containing customer data to one advertising contractor. [1]

2. 2021-04-02

   In the same way, the bank emailed a spreadsheet containing customer data to the same contractor. [1]

3. 2021-04-12

   A regular internal inspection found the April 2 email. A check for similar mistakes found the one sent on January 8. [1]

4. 2021-04-16

   The bank announced the case. [1]

The file sent by mistake held data on 41,729 customers: names in katakana, phone numbers, genders, birth dates, email addresses, branch numbers, account numbers, log-in IDs for the smartphone payment service Hama Pay and more. The attachment was encrypted automatically when sent, but an employee told the password through the same route. [1]

The bank had long emailed this contractor spreadsheets of statistics about customers. In these two cases, it did not notice that another sheet in the file held customer data and sent the file as it was. [1]