Marubishi Holdings: ransomware disabled its business systems, and group staff My Numbers and partner contracts were leaked

1. 2025-07-26

   A server failed and several business systems became unusable. It confirmed traces of unauthorized access and cut the server off from its networks. [2]

2. 2025-07-28

   It announced the ransomware attack and reported to the Personal Information Protection Commission. It said no outside leak of personal data had been confirmed. [1] [2] [4]

3. 2025-07-29

   It consulted the police. [2]

4. 2025-08-05

   It announced that some personal and confidential information had leaked. [2] [3]

The leaked items include some personal data of staff of the company and group firms, including former staff and contract workers (email addresses, phone numbers, addresses, family details, My Numbers and more), partner contracts and invoices, some data on past job applicants and past customers, and legal, finance, HR, sales and technical documents. No counts were published. [2] [3]