Gion: ransomware in its document management system
Encryption of the document-management system was detected on May 7, 2024 and publicly reported the following May. Sompo Japan identified about 75,000 customer-name entries potentially accessed, without confirmed leakage or misuse. The system was rebuilt in a separate environment on July 18, 2024 and moved to the cloud on October 30.
Disclosed
2025-05-01
Organizations involved
2
Leaked or at risk
75K
75,000
Downtime
Unknown
Timeline
- Detected 2024-05-07
- Disclosed 2025-05-01
- 359 days
Attack or cause
- Method
- [Ransomware]
- Impact
- [Data leak][Service outage]
- Entry point
- Unknown
Data exposed or at risk
Supply chain
Organizations involved
[Through a supplier][Major]Tokyo, ShinjukuFinance and insurance75,000 leaked
Sompo Japan Insurance Inc.[Breached][Major]Kanagawa, Sagamihara, ChuoTransport and postal services
Gion Co., Ltd.
Sources
- [1][Official]不正アクセスに関するご報告Gion Co., Ltd. · 2025-05-01
- [2][Official]当社委託先におけるランサムウェア被害に伴う情報漏えいのおそれについてSompo Japan Insurance Inc. · 2025-05-01