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Cyber Attack & Data Breach · rocket-boys.co.jp

Ransomware Hits CKC Network and Gakusan System; Personal Data Exposure Remains Possible

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Summary

CKC Network and Gakusan say ransomware hit their shared inquiry-management system. They have not confirmed data loss or external transfer, but cannot rule out exposure of students’ personal information and are investigating.

Key points

  • The companies say the ransomware attack targeted a server for their shared new-inquiry management system.
  • No damage to data files or external data transfer has been confirmed; possible exposure remains under investigation.
  • Potentially affected information includes students’ names, grades, tutoring inquiries and consultation details, and some phone numbers and email addresses.
  • The system reportedly did not store credit-card or bank-account information.
  • The companies shut down the server to prevent further harm and are working with an external investigation firm; the attack method is not yet known.
  • Current student- and member-facing systems are in a separate environment, which the companies say was not affected.

Article Details

Victim Organization
CKCネットワーク株式会社 and 株式会社学参
Victim Domain
Unknown
Incident Type
Ransomware cyberattack against a server supporting a jointly operated new inquiry information management system
Incident Date
2026-05-15
Disclosure Date
2026-05-15
Data Types Exposed
  • Potentially exposed: children's names, including some kanji names
  • Potentially exposed: students' grades at the time of inquiry
  • Potentially exposed: learning consultation contents and other inquiry contents
  • Potentially exposed for some individuals: telephone numbers and email addresses
Affected Records
Not disclosed
Affected Data Size
Not disclosed
Operational Impact
The affected server was shut down to prevent secondary damage. The companies said current student- and member-facing systems operate in a separate environment and were unaffected. Data-file damage and actual external transfer or leakage were not confirmed.
Ransom Or Extortion
Unknown
Claim Status
confirmed