SHINDO3

Tohoku Electric Power Network

Tohoku Electric Power Network Co., Inc.

Personal data769records

LEAK CONFIRMEDSoftware defect · Contained

Open in the live monitor ▶
Disclosed
Jun 23, 2025
Leak
Leak confirmed
Type
Software defect
Status
Contained
Security spend
Not checked yet
Compensation
Not announced

What leaked

UnspecifiedCustomer information

How many

  • Records confirmed to have been viewed 769 records

Who is affected

  • Customers contracted with electricity retailers other than Tohoku Electric

Cause

A program design error. On the screen for managing new connection work applications, especially when a contract switched to another retailer right after the work was done, some customer data that should have been hidden from Tohoku Electric could be viewed

Timeline

  1. Date of the Security NEXT report

Response

  • Notified individuals
  • Change process

Fixed the system so the data cannot be viewed and contacted affected customers individually

What you should do

  1. Check the company's notice to see if you're affected

Lessons for companies

  1. Never sit on a known defect. Test every change before production
  2. Report to the PPC: preliminary in 3–5 days, final in 30 (60 if malicious)
  3. Run red teaming and AI-assisted hardening, and publish how much you invest

Sources