> JapanHacked_
[Resolved][Severity: Critical][Lost device]

Mizuho Research Institute: six backup tapes holding about 2.5 million customer and usage records went missing

The company said the tapes had most likely been thrown away by mistake. They also held data of a members' program run with Mizuho Bank and of work done for the bank.

Disclosed

2020-07-21

Organizations involved

2

Leaked or at risk

2.5M

2,507,000

Downtime

Unknown

What happened

Six LTO backup tapes kept by Mizuho Research Institute could not be found. There was no sign that they had been taken out, and the company said they had most likely been thrown away by mistake. [1] [2]

  1. Mizuho Research Institute and Mizuho Bank disclosed the loss. [1] [2]

Impact

The tapes held about 2,507,000 records in all on customers who dealt with the company up to December 7, 2018, including names, company names, addresses, email addresses, account numbers and service usage. About 2.4 million concerned individuals and about 107,000 companies. [2] [3] [4]

Reading the tapes needs special equipment, so the company said the chance of a third party reading them was low. [2] [3]

Timeline

  1. Disclosed 2020-07-21
  2. 1 days

Attack or cause

Method
[Lost device]
Impact
[Data leak]
Entry point
Unknown

Data exposed or at risk

[Name][Postal address][Phone number][E-mail address][Bank account][Employment]

Supply chain

Mizuho Research Institute Ltd.

[Breached]

Organizations listed on this site
2

Organizations involved

  • [Through a supplier][Critical]Tokyo, ChiyodaFinance and insurance

    Mizuho Bank, Ltd.

    The tapes held about 51,000 corporate records of the jointly run MIZUHO Membership One program and data from consulting work the bank had outsourced.

  • [Breached][Critical]Tokyo, ChiyodaScientific research, professional and technical services2,507,000 leaked

    Mizuho Research Institute Ltd.

    It merged with Mizuho Information & Research Institute in 2021 to form Mizuho Research & Technologies, which was merged into Mizuho Bank in 2026.

Open in organization search

Sources

  1. [1][Official]みずほ総合研究所株式会社におけるお客さま情報の紛失についてMizuho Bank · 2020-07-21
  2. [2][News]顧客情報250万件を紛失 みずほ総研、媒体破棄かThe Sankei Shimbun · 2020-07-21 23:33
  3. [3][News]みずほ総研、約250万件の顧客情報が入った記録媒体を誤廃棄か　「情報流出の可能性は低い」ITmedia NEWS · 2020-07-22 21:31
  4. [4][News]みずほ総研で最大250万件の顧客情報紛失、磁気テープを誤廃棄の可能性Nikkei xTECH · 2020-07-22
  5. [5][News]顧客情報約250万件含む磁気テープを紛失 - みずほ総研Security NEXT · 2020-07-22