CS Accounting: unauthorized access to its servers
Early on 5 May, the EDR at CS Accounting, which provides accounting and HR outsourcing and cloud services, detected suspicious behavior on some servers, which were isolated. A system account had been taken over by a password brute-force attack from overseas IP addresses and used to log on to some servers. Servers for its cloud services were not entered, and no leak of personal or confidential data was found.
Disclosed
2026-05-15
Organizations involved
1
Leaked or at risk
Unknown
Downtime
Unknown
Timeline
- Detected 2026-05-05
- Disclosed 2026-05-15
- 10 days
Attack or cause
- Method
- [Credential abuse]
- Impact
- Entry point
- Stolen credentials
Data exposed or at risk
–
Organizations involved
[Breached][Moderate]Tokyo, ShinjukuScientific research, professional and technical services
CS Accounting Inc.
Sources
- [1][Official]【重要】弊社サーバーにおける不正アクセスに関する最終報告CS Accounting · 2026-05-15