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KOIKE Sanso Kogoyo Co. Ltd.

Claimed by Exitium · listed 3 hours ago

Today
Age
since listed · data leaked

Status timeline

  1. ListedOct 10, 2026
  2. Data leakeddate unknown

At a glance

Group
Exitium
Status
Data leaked
Country
Japan
Sector
Manufacturing
Listed on leak site
Oct 10, 2026

About the victim

AI dossier — public-source company profile

KOIKE Sanso Kogoyo Co. Ltd. is a Japanese manufacturing company operating under the domain koike-japan.com. Limited public information is available beyond the company name and web presence.

Industry
Industrial Manufacturing

Attack summary

Severity: high — Confirmed exfiltration of 5.8 TB including proprietary engineering drawings, customer/client databases, and confidential business correspondence. Engineering data theft from a manufacturing firm poses significant competitive and operational risk.

The exitium group claims to have exfiltrated 5.8 TB of data from KOIKE Sanso Kogoyo Co. Ltd., including confidential agreements, correspondence, customer and client records, and engineering drawings. The group issued a deadline of Tuesday, October 13, 2026, threatening to sell the data if contact was not established.

high

Data the group says was taken

AI dossier — extracted from the leak post
  • confidential agreements
  • correspondence
  • customer and client data
  • engineering drawings

What the group claims

Website: koike-japan.com You have time until Tuesday(10.13.2026). If you wouldn't contact us we will start selling data. We have 5.8 TB of data: agreements confidential data correspondence files all customers and clients data engineering drawings AND MUCH MORE... Contact us until your time runs out.

The leak post

captured from the group's site
Website: fannincad.org Zoominfo: https://www.zoominfo.com/c/fannin-central-appraisal-district/1117264519 Exfiltrated: 400 GB of data
Website: marborges.com Zoominfo: https://www.zoominfo.com/c/marborges-agroindustria/547271801 Company in Brasil with a bad security.
Website: mhe.com.tw Zoominfo: https://www.zoominfo.com/c/ming-hwei-energy-co-ltd/446006038 A small private B2B firm (11–50 staff, <$5M revenue), part of a Taiwanese fastener conglomerate. Manufacturer of solar cells in a niche where Taiwanese firms are consistently undercut by Chinese pricing. Their infra encrypted.
Gastroenterology & Hepatology of CNY
Gastroenterology & Hepatology of CNY, P.C. (gandhofcny.com) + Digestive Disease Center of CNY, LLC (ddcofcny.com). GI practice + AAAHC-accredited endoscopy center. Syracuse, New York, USA. Full database — 167,303 patients, 124,761 SSN, 46,181 with sensitive diagnoses: - 167,303 patients — 124,761 with SSN, 166,402 (99%) with address, 164,296 (98%) with phone, 85,318 (51%) with email - 1,093,863 diagnoses (ICD-10), 1,547,142 medications, 186,246 pathology specimens with narrative reports - Sensitive (dx + meds): 46,181 patients — 41,645 with SSN. Mental health: 39,784 | Sub…

Sources

Source

Indexed 3 hours ago

This page surfaces a public ransomware disclosure indexed by Darkfield. Original posts come from the operator's own leak site; we cross-check against ransomware.live, RansomLook and RansomWatch where applicable. Share this URL freely.

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Disclosure context

About exitium

Exitium is an emerging ransomware group that was first observed in March 2026, operating with apparent financial motivations based on their limited but documented attack patterns. Given the recent emergence and limited public documentation, specific details about the group's country of origin, organizational structure, or potential affiliations remain unclear to security researchers and law enforcement agencies. The group's attack methodology and technical capabilities have not been extensively documented due to their recent appearance and small victim count, though they appear to target specific sectors rather than conducting widespread campaigns. Exitium has been observed targeting organizations in the United States and Brazil, with a particular focus on the agriculture and food production sector as well as public sector entities, suggesting possible strategic targeting of critical infrastructure. The group remains active as of their recent emergence, though their limited victim count of two documented cases indicates they are either highly selective in their targeting, newly operational, or operating at a smaller scale compared to established ransomware groups. The group has been linked to 12 public disclosures across our corpus. First observed on a leak site on March 17, 2026; most recent post October 10, 2026. The operation is currently active.

Timeline of this disclosure

  • October 10, 2026KOIKE Sanso Kogoyo Co. Ltd. listed by exitium on the group's public leak site

Other recent disclosures by exitium

exitium has been linked to 12 public victims on Darkfield. A sample of the most recent:

See the full exitium dossier →

Sector and geography

This disclosure adds to ransomware activity in the Manufacturing sector, which has 3,699 disclosures indexed across all operators we track. Geographically, KOIKE Sanso Kogoyo Co. Ltd. is reported in Japan, a country with 89 ransomware disclosures in our corpus.

If your organisation is affected

A listing by exitium means KOIKE Sanso Kogoyo Co. Ltd. appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.

  • Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
  • Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
  • Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
  • Report the incident to your national CERT, JPCERT/CC (Japan), as required for your jurisdiction.
  • Monitor for the data appearing on exitium's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.

How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.