Nostrum
bd_ff261fee6341fc80 · schema v1 · pii pii-v1
Full breach record for Nostrum →Threat-actor claim — not a regulatory filing
This row is a claim by the ransomware group Thegentlemen on its public extortion blog. It has not been validated by the victim or any regulator. Treat attribution and counts as the threat actor's assertion until a regulatory filing or victim disclosure corroborates them.
Source: Ransomware.live
Post text · scraped from the leak site
nostrum.co.jp Nostrum Corporation, based in Japan, was founded in 1991 and specializes in smartphone app development, web system development, and website construction. The company is represented by Ryoichi Jono and is registered on the J-GoodTech platform as a verified Japanese technology business. One of their flagship self-developed products is a job aptitude test preparation tool — a simulation platform replicating real SPI, TG-WEB, and similar employment exam interfaces used by major Japanese companies
J jump to incidentP pin to compareR raw source
Incident timeline — mostly unverified
? — ?
Breach window unknown
Apr 27, 2026
Claim posted
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No filing yet · watching
Compliance clocks stay unassessable until a regulatory filing lands. Dashed segments fill in automatically when corroboration arrives.
Claim → filing
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Compliance clock
Not assessable
Linked disclosures
Why this link?Press reports (1)
- Pressthegentlemenbd_6f7159c6684efe482026-04-19 · +8dCandidate
Evidence ladder
Attacker assertion only. Establishes: claim date, group, alleged victim.
Unlocks: incident narrative, operational impact. Still no compliance clock.
Unlocks: discovery date, data types, affected count, compliance clock.
Unlocks: materiality, stated response, full audit trail. Ceiling removed.
No regulatory filing corroborates this yet — it is the attacker's own assertion. Watch this entity to be notified the moment a filing corroborates or contradicts it.
Source ceiling
- actor name
- victim claim
- ransom/leak status
- discovery date
- materiality
- notification
- affected count
- confirmed data types
- compliance clock
The ✕ fields stay blank until a regulatory filing or victim disclosure lands.
thegentlemen
According to ransomware.live, The Gentlemen is a RaaS group that emerged in July–August 2025, rapidly claiming over 320 victims across 17+ countries by offering affiliates a 90% revenue share, deploying a Go-based locker against Windows, Linux, NAS, and BSD systems; a compromised C2 server in 2026 revealed more than 1,570 linked victims.