Was OTNet hit by ransomware?

OTNet was listed by the nightspire ransomware operation (Japan), and stolen data was published on the group's leak site. Darkfield tracks this disclosure with the original leak post, screenshot and group context.

Who is the nightspire ransomware group?

nightspire is a ransomware operator tracked by Darkfield. See the full operator dossier for its known victims, sectors targeted, IOCs and leak-site infrastructure.

What data was leaked in the OTNet breach?

nightspire published data attributed to OTNet. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

← All victims

OTNet株式会社 (OTNet Company, Incorporated)

listed as OTNet · Claimed by Nightspire · listed 3 months ago

Age

since listed · data leaked

Status timeline

ListedMar 28, 2026
Data leakeddate unknown

At a glance

Group: Nightspire
Status: Data leaked
Country: Japan
Listed on leak site: Mar 28, 2026

About the victim

AI dossier — public-source company profile

OTNet Company, Incorporated is an Okinawa-based telecommunications and network infrastructure provider established in 1996, and a member of the Okinawa Cellular Group. The company provides fiber-optic broadband, internet, cloud, security, and voice services with a 24/7 operations and maintenance regime, serving public sector, financial, medical, education, and tourism clients across Okinawa.

Industry: Telecommunications & Network Infrastructure
Address: 〒900-0032 沖縄県那覇市松山1-2-1 沖縄セルラービル (Okinawa Cellular Building, 1-2-1 Matsuyama, Naha-shi, Okinawa 900-0032, Japan)
Founded: 1996

Attack summary

Severity: high — OTNet is a critical telecommunications infrastructure provider serving public, financial, medical, and government sectors in Okinawa; data_published status confirms exfiltration and public release, posing significant risk to both the company and its institutional customers.

The Nightspire ransomware group claims an attack on OTNet with the disclosure status recorded as data_published, indicating data has been exfiltrated and published. No further detail on the volume or specific nature of the published data is available from the leak post.

high

Data the group says was taken

AI dossier — extracted from the leak post

Corporate data (unspecified)
Potentially customer or network operational data

Original description

AI-summarised, not from the leak post

N/A

Sources

Victim sitewww.otnet.co.jp

Source

Indexed 3 months 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 nightspire

Nightspire is a ransomware group that first emerged in March 2025 and appears to be primarily financially motivated, having targeted over 215 victims in a relatively short operational timeframe. The group's origin and affiliations remain unclear due to limited public documentation from major cybersecurity organizations, though their targeting patterns suggest a broad opportunistic approach rather than nation-state backing. Based on available victim data, Nightspire appears to employ common ransomware attack vectors targeting organizations across multiple sectors, with a particular focus on manufacturing, technology, healthcare, and construction industries, while demonstrating a geographic preference for victims in the United States, India, Taiwan, France, and Hong Kong. The group's rapid victim acquisition rate since their March 2025 emergence suggests an active and potentially effective operational capability, though specific technical details about their attack methodology, encryption techniques, or extortion tactics have not been publicly documented by major threat intelligence firms. Given the recent emergence of this group and limited public reporting from established cybersecurity organizations like CISA, FBI, or Mandiant, Nightspire remains an active threat with insufficient public documentation to fully assess their operational sophistication or organizational structure. The group has been linked to 283 public disclosures across our corpus. First observed on a leak site on March 12, 2025; most recent post June 12, 2026. The operation is currently active.

Timeline of this disclosure

March 28, 2026OTNet listed by nightspireon the group's public leak site

Other recent disclosures by nightspire

nightspire has been linked to 283 public victims on Darkfield. A sample of the most recent:

See the full nightspire dossier →

Sector and geography

Geographically, OTNet is reported in Japan, a country with 108 ransomware disclosures in our corpus.

If your organisation is affected

A listing by nightspire means OTNet 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.
Monitor for the data appearing on nightspire'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.