> JapanHacked_
[Contained][Severity: Major][Ransomware]

Nippon Telenet: a ransomware-type attack encrypted some server files; no trace of data being sent outside was found

Nippon Telenet suffered a ransomware-type attack that encrypted some server files; its investigation found no trace of data being sent outside.

Disclosed

2026-03-17

Organizations involved

5

Leaked or at risk

Unknown

Downtime

Unknown

What happened

  1. A server failure occurred. Some files appear to have been encrypted by a ransomware-type attack. [1] [3]

  2. It announced the system failure caused by a cyberattack. [1]

  3. UPR, which had subcontracted call-center work, announced that member data may have leaked. [5]

  4. Mobility Platform announced that Nippon Telenet, a re-subcontractor for "MaaS Car", had been attacked. [6]

  5. Kyuden Real Estate announced that its re-subcontractor Nippon Telenet had been attacked. [7]

  6. Daiwa Lease announced that D-Share car-sharing member data may have leaked through unauthorized access at the call-center contractor. The work had been passed from UPR to Nippon Telenet. [2] [4]

  7. It published its investigation results and measures to prevent recurrence. No trace of data being transferred outside was detected. [8] [9]

Impact

The published material does not give the number of members who may be affected. [2] [4]

Timeline

  1. Started, Detected 2026-03-09
  2. Disclosed 2026-03-17
  3. 8 days

Attack or cause

Method
[Ransomware]
Impact
[Data leak][Service outage]
Entry point
Supplier

Data exposed or at risk

[Name]

Supply chain

Nippon Telenet Co., Ltd.

[Breached]

Organizations listed on this site
5

Organizations involved

Open in organization search

Sources

  1. [1][Official]サイバー攻撃によるシステム障害発生についてNippon Telenet Co., Ltd. · 2026-03-17
  2. [2][Official]＜重要＞Dシェア（カーシェアリングサービス）業務委託先に対する不正アクセスによる個人情報の漏えいの可能性に関するご報告とお詫びDaiwa Lease Co., Ltd. · 2026-04-23
  3. [3][News]日本テレネットにランサムウェア型サイバー攻撃、サーバのファイルの一部が暗号化ScanNetSecurity · 2026-05-07 08:05
  4. [4][News]日本テレネットにランサムウェア型サイバー攻撃、大和リースのカーシェアリングサービス「Dシェア」の会員情報が漏えいした可能性ScanNetSecurity · 2026-05-14 08:05
  5. [5][News]日本テレネットへのランサムウェア型サイバー攻撃、コールセンター業務を委託していたユーピーアールの会員情報が漏えいした可能性ScanNetSecurity · 2026-05-07 08:05
  6. [6][News]「MaaS Car」再委託先の日本テレネットにランサムウェア攻撃、会員情報が漏えいした可能性ScanNetSecurity · 2026-05-07 08:05
  7. [7][News]九電不動産 再委託先の日本テレネットにランサムウェア攻撃ScanNetSecurity · 2026-05-08 08:05
  8. [8][Official]サイバー攻撃によるシステム障害発生に関する調査結果および再発防止策についてNippon Telenet Co., Ltd. · 2026-06-12
  9. [9][News]日本テレネットにランサムウェア型サイバー攻撃、データが外部に転送された痕跡は検出されずScanNetSecurity · 2026-07-27 08:05