
Japan cyberattack database
JapanHacked is a database of cyberattacks and data leaks that hit organizations in Japan. Each incident lists the organizations affected, how the attack worked, how many records leaked and when it was disclosed, with official notices and news reports as sources.
Spotlight
[Investigating][Severity: Critical]Disclosed 2026-10-21Updated 2026-10-27 19:58Day 9 since disclosureOn 20 October GMO Internet found that a third party had placed a malicious program on some customer servers of Onamae.com Desktop Cloud, its Windows remote desktop service. 26,739 servers may be affected, and it began shutting down servers on all plans from 04:00 on 21 October. Login details for trading tools such as FX platforms saved on the servers were used, and customers reported trades in their accounts that they had not made. Its fourth report on 24 October admitted a security flaw in the service's systems and confirmed customer data was taken out. It will pay every user a flat ¥5,000, compensate realized losses from unauthorized trades and offer a replacement service free for six months. It consulted the police and asked the government to respond with active cyber defence measures. On 25 October group chairman and CEO Masatoshi Kumagai apologized on his blog, admitting that in-house engineers had raised security issues with the service that were not dealt with in time. The damage may reach users' own PCs. According to GMO's user guide, the RDP connection files it handed out turned on file sharing with the user's PC by default, which lets the server side see the drives of the user's own computer. From 25 October GMO collected users' PCs across Japan for analysis; its ninth report at 11:59 on 27 October said no malware had been found on the devices analysed so far. GMO's timeline says a threatening email on 21 October demanded about ¥8 billion. Kumagai wrote on his blog on 26 October that the demand was USD 50 million in crypto assets (Sankei Shimbun). The apparent attacker later demanded USD 1 million by noon on 27 October and threatened to publish users' data and launch ransomware attacks if not paid (ITmedia NEWS). TV Asahi reported the attackers claim to have planted a backdoor that lets them back into users' PCs without logging in; this is an unverified claim, and GMO has not confirmed any intrusion into users' PCs. GMO says it will not pay. Its eighth report on 27 October asked users to back up their data, disconnect their PCs from the network and switch them off before noon, and it will give users hit by ransomware an equivalent new PC. According to its tenth report, at 12:30 on 27 October GMO confirmed that the apparent attacker had published information it claims concerns GMO and its customers. GMO is checking the content, warns it may contain false information, asks people not to access or share it and is preparing legal action against malicious spreaders. It will contact customers whose data is included and is considering steps beyond the flat payment. As of 13:55 no ransomware attack had been confirmed. Its eleventh report at 14:55 said it had confirmed that the attacker collects data on anyone who visits the attacker's site, repeated its request not to visit it and advised those who had to run a full antivirus scan. On 27 October Financial Services Minister Katayama named five FX firms that reported customer damage thought to be linked to GMO: Goldenway Japan, OANDA Securities, AvaTrade Japan, Gaitame Finest and Dukascopy Japan. Trading account logins stored on the servers appear to have been taken and used for unauthorized trades. The firms suspended trading for affected customers and blocked unauthorized orders. Amounts were not disclosed. The Goldenway Japan case is covered as a separate incident.
Latest source 2026-10-27 · GMO Internet Group 【重要】「お名前.com デスクトップクラウド」への不正アクセスに関する現在の対応について(第8報)(【続報】お客様をお守りするために現在私たちが行っていること)
> Full detailsSpotlight
[Ongoing][Severity: Moderate]Disclosed 2026-10-21Updated 2026-10-27 09:05Day 9 since disclosureDetails of two critical flaws in PHP leaked before the fix, and ministries, local governments, banks and companies across Japan paused websites and services as a precaution.
- [Precautionary halt]
- Hiroshima Prefecture,Ibaraki Prefectural Police,Iwate Prefecture,NTT DOCOMO, Inc.,SoftBank Corp.,Aomori Michinoku Bank, Ltd.,Itabashi City,Kasukabe City
Latest source 2026-10-26 · Miyagi Prefecture 宮城県が管理・利用するウェブサイト・システムの一部停止について(令和8年10月21日に発覚したPHPの脆弱性対応)
> Full detailsLatest disclosures and updates
By date of disclosure or follow-up report, newest first
2026-10-27
[Update][Severity: Critical]Disclosed 2026-10-19Updated 2026-10-27 17:02Aichi, Fukuoka, Osaka and 2 more prefecturesLeaked 51.6MOrganizations 15
Ymirlink: unauthorized access to the Cuenote FC email delivery serviceNew official notice · Resona Holdings 外部委託先への不正アクセスによるお客さま情報の漏えいの可能性について
[Update][Severity: Critical]Disclosed 2026-10-07Updated 2026-10-27 19:58Aichi, Fukuoka, Hiroshima and 3 more prefecturesLeaked 4MOrganizations 495
IDC Frontier: ransomware attack on IDCF CloudNew official notice · Soliton Systems 【第16報】Soliton SecureDesktopサービス 障害のお知らせ
[New][Severity: Critical]Disclosed 2026-10-27Updated 2026-10-27 19:58TokyoLeaked 2.6MOrganizations 1
Sony Network Communications: unauthorized access to the So-net member database leaks data of about 2.59 million members[Update][Severity: Critical]Disclosed 2026-10-21Updated 2026-10-27 19:58Aichi, Fukuoka, Hiroshima and 9 more prefecturesOrganizations 345
RAKUS Light Cloud: unauthorized access to the blastmail email delivery serviceNew official notice · Daihatsu Motor 【お知らせ】 当社が利用する外部サービスへの不正アクセスに伴う個人情報漏えいについて
[Update][Severity: Major]Disclosed 2026-10-22Updated 2026-10-27 17:02AichiLeaked 15.7KOrganizations 1
System5: unauthorized access to a system linked to the online shopNew official notice · System5 不正アクセスによる情報流出に関するお詫びと調査結果のご報告
[New][Severity: Major]Disclosed 2026-10-27Updated 2026-10-27 17:02TokyoLeaked 14KOrganizations 2
Smartshare: unauthorized access to the OWNLY SNS campaign tool leaks Mos campaign entrants' data[Update][Severity: Major]Disclosed 2026-10-22Updated 2026-10-27 17:02Ehime, TokyoOrganizations 2
Level Enter: unauthorized access to the AI.R-Scorer essay scoring serviceNew official notice · Nitta High School 外部の作文添削サービスへの不正アクセスによる個人情報漏えいのおそれについて(お知らせとお詫び)
[New][Severity: Major]Disclosed 2026-10-27Updated 2026-10-27 17:02TokyoOrganizations 1
Basic: unauthorized access to the ferret One marketing platform[New][Severity: Major]Disclosed 2026-10-27Updated 2026-10-27 17:02TokyoOrganizations 1
Hiroshima Gakuin Junior and Senior High School: unauthorized access to Microsoft 365 accounts[New][Severity: Moderate]Disclosed 2026-10-27Updated 2026-10-27 17:02OsakaOrganizations 1
URBAN RESEARCH: official X account taken over[Unknown][Site defacement]
2026-10-26
[Update][Severity: Critical]Disclosed 2026-09-30Updated 2026-10-27 17:02Akita, Kyoto, TokyoLeaked 53.2MOrganizations 4
Sagawa: unauthorized access to the parcel tracking serviceNew official notice · Zeria Pharmaceutical 配送委託先(佐川急便)における個人情報流出の可能性に関するお知らせとお詫び
[Update][Severity: Critical]Disclosed 2026-10-17Updated 2026-10-27 08:40OsakaLeaked 6MOrganizations 1
Joshin: unauthorized accessNew official notice · Joshin 不正アクセスによるシステム障害発生のお詫びとお知らせ(第2報)
[New][Severity: Critical]Disclosed 2026-10-26Updated 2026-10-27 08:40TokyoLeaked 2.6MOrganizations 1
Rakuten Group: unauthorized access to Rakuten Travel's overseas hotel pages and multilingual booking site[Update][Severity: Critical]Disclosed 2026-10-22Updated 2026-10-27 17:02TokyoLeaked 4.1KOrganizations 1
KOMOJU: unauthorized access to payment and CRM systemsNew official notice · KOMOJU 【第二報】当社 CRM システムにおける個人データの漏洩について
[New][Severity: Critical]Disclosed 2026-10-26Updated 2026-10-27 14:31TokyoLeaked 951Organizations 1
Doutor Coffee: unauthorized access; employee data may have leaked[Update][Severity: Critical]Disclosed 2026-10-16Updated 2026-10-27 19:58Aichi, Chiba, Fukushima and 7 more prefecturesOrganizations 28
Studio: unauthorized access to the cloud environment of the Studio website builderNew official notice · Money Forward 外部サービス「Studio」への不正アクセスに伴う、お問い合わせフォームにおける個人データ流出の可能性に関して
[New][Severity: Critical]Disclosed 2026-10-26Updated 2026-10-27 08:40TokyoOrganizations 2
Bandai Logipal: unauthorized access; Ichiban Kuji ONLINE delivery data may have leaked[New][Severity: Critical]Disclosed 2026-10-26Updated 2026-10-27 14:31IwateOrganizations 1
Wiseman: unauthorized access to the MeLL+professional care service[Update][Severity: Critical]Disclosed 2026-10-22Updated 2026-10-27 14:31TokyoOrganizations 1
VALTEC: unauthorized access; customer data may have leakedNew official notice · VALTEC 《第三報》不正アクセスによるお知らせ
[Update][Severity: Critical]Disclosed 2026-10-15Updated 2026-10-27 14:31MiyagiOrganizations 1
Maruki Medical Systems: cyberattack stops orders and shippingNew official notice · Maruki Medical Systems 【続報】弊社システム障害に関するお詫びとご案内