Disclosure context

About Rhysida

Rhysida is a ransomware group that emerged in June 2023, operating with primarily financial motivations through targeted attacks against critical infrastructure and public sector organizations. The group's origin and potential state affiliations remain unclear, though they operate independently rather than as a traditional Ransomware-as-a-Service model, with limited public documentation regarding connections to other cybercriminal organizations. Rhysida employs double extortion tactics, typically gaining initial access through compromised VPN credentials and exploiting vulnerable public-facing applications before deploying their ransomware payload and exfiltrating sensitive data prior to encryption. The group has demonstrated a particular focus on healthcare and educational institutions, with notable attacks documented by CISA and FBI advisories highlighting their targeting of hospitals and school districts across multiple countries, resulting in significant operational disruptions to critical services. As of late 2024, Rhysida remains an active threat with continued operations targeting organizations primarily in the United States, Canada, and other Western nations, maintaining their focus on high-value sectors where operational disruption can maximize ransom payment likelihood. The group has been linked to 278 public disclosures across our corpus. First observed on a leak site on June 5, 2023; most recent post May 20, 2026. The operation is currently active.

Timeline of this disclosure

February 17, 2026Cheyenne & Arapaho Tribes listed by Rhysidaon the group's public leak site

Sector and geography

This disclosure adds to ransomware activity in the Public Sector sector, which has 259 disclosures indexed across all operators we track. Geographically, Cheyenne & Arapaho Tribes is reported in United States, a country with 7,392 ransomware disclosures in our corpus.

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.

Ransomware victim disclosure

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Cheyenne & Arapaho Tribes

Claimed by Rhysida · listed 3 months ago

Age

since listed · data leaked

Status timeline

Listed
Feb 17, 2026
Data leaked

At a glance

Group: Rhysida
Status: Data leaked
Country: United States
Sector: Public Sector
Listed on leak site: Feb 17, 2026

About the victim

AI dossier — public-source company profile

The Cheyenne and Arapaho Tribes are a federally recognized tribal nation in western Oklahoma, representing the Tsistsistas (Cheyenne) and Hinono'ei (Arapaho) peoples united since the early 19th century. The tribal government administers a range of public services including health, education, housing, and economic development programs for their enrolled membership and surrounding communities.

Industry: Tribal Government & Public Administration
Address: 100 Red Moon Circle, Concho, Oklahoma 73022, United States
Employees: 201-500

Attack summary

Severity: critical — The victim is a federally recognized tribal government. Such entities hold regulated PII at scale including tribal enrollment records, health data, social services records, and financial information for enrolled members — all categories of sensitive data whose exfiltration meets the critical threshold. Data has been confirmed published by the group.

Rhysida claims to have compromised the Cheyenne and Arapaho Tribes and has published data (disclosed status: data_published), indicating exfiltration of tribal government records; the specific data categories and volume have not been enumerated in the available post excerpt.

critical

Data the group says was taken

AI dossier — extracted from the leak post

Tribal government records
Enrolled member personal information
Administrative documents

What the group claims

Cheyenne & Arapaho Tribes The Cheyenne and Arapaho Tribes are a federally recognized united nation of two distinct peoples-the Tsistsistas (Cheyenne) and Hinono'ei (Arapaho)-with a historic alliance formed in the early 19th century.

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.