YCC Information SystemsYamagata City and other municipalities

1MinorInvestigatingAnnounced

A ransomware attack on a municipal systems vendor may have exposed resident, tax and insurance data of local governments, partly including My Number and salary information.

This incident was imported from a dataset that compiles public announcements, and we are still checking it against the sources. Counts and causes will be updated after the check. Sources are in Japanese.

Cause
Ransomware, Via a vendor or service
Occurred
2026-04-02
Sector
Public sector
Operational impact
None

Tools for this kind of attack

Picked from the cause of the incident: tools that help you check your own systems for the same kind of weakness, or spot the warning signs.

Wazuh

Impact Local only
wazuh/wazuh

A free security platform (SIEM/XDR) that collects logs, configuration, and vulnerability data from agents on your endpoints and shows it all in one dashboard.

Purpose
Defense
Type
Self-hosted server
Difficulty
Advanced
License
CopyleftGPL-2.0(一部の構成要素は Apache-2.0)
Category
Vulnerability scanning / Forensics
Actively updatedstars17,410Last update 2026-10-24
Read the Wazuh review

Vuls

Impact Reaches others
future-architect/vuls

An agentless vulnerability scanner that checks the packages installed on a server and lists the ones affected by known CVEs.

Purpose
Defense
Type
Command line
Difficulty
Intermediate
License
CopyleftGPL-3.0
Category
Vulnerability scanning
Actively updatedstars12,302Last update 2026-10-21
Read the Vuls review

Sources

  1. 株式会社YCC情報システムに対する不正アクセス発生に関する報告についてwww.city.higashine.yamagata.jp(opens in a new tab)
  2. 【重要】当社サーバーへの不正アクセスに関するご報告www.yamagata-ycc.co.jp · Published 2026-04-03(opens in a new tab)
  3. 【重要】ランサムウェア攻撃に関するお知らせ(第二報)www.yamagata-ycc.co.jp · Published 2026-04-06(opens in a new tab)
  4. 【重要】ランサムウェア攻撃に関するお知らせ(第三報)www.yamagata-ycc.co.jp · Published 2026-04-07(opens in a new tab)
  5. 【重要】ランサムウェア攻撃に関するお知らせ(第四報)www.yamagata-ycc.co.jp · Published 2026-04-14(opens in a new tab)
  6. 【重要】ランサムウェア攻撃に関するお知らせ(第五報)www.yamagata-ycc.co.jp · Published 2026-05-20(opens in a new tab)
  7. 株式会社YCC情報システムに対するサイバー攻撃に係る山形市保有個人情報の漏えいのおそれがある事案についてwww.city.yamagata-yamagata.lg.jp(opens in a new tab)