SHINDO2

Sumitomo Mitsui Trust Bank

Sumitomo Mitsui Trust Bank, Limited

LossSize not disclosed

LEAK UNCLEARPostal address / Full nameClosed (final report)

Open in the live monitor ▶
Disclosed
Oct 9, 2025
Leak
Unknown
Type
Loss
Status
Closed (final report)
Security spend
Not checked yet
Compensation
Not announced

What leaked

IdentityFull name
ContactAddress

Not leaked

  • Account number
  • PIN

Who is affected

  • Customers

Cause

Electronic media holding customer data were found missing during routine storage checks; they were most likely discarded by mistake

Timeline

  1. Date of the Security NEXT report

Response

  • Notified individuals

What you should do

  1. Watch for unexpected mail or invoices; your address is hard to change
  2. Check the company's notice to see if you're affected

Lessons for companies

  1. Report to the PPC: preliminary in 3–5 days, final in 30 (60 if malicious)
  2. Run red teaming and AI-assisted hardening, and publish how much you invest

Sources