MalwareHealthcareTechnologyHealthcareRansomwareCapture Stored DataData ExfiltratedData EncryptedCustomer Data InvolvedIdentity (basic)Government IDMediumContained

Horizon Healthcare RCM

bd_c5493de054e7d752 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Dec 27, 2024

Filed

Nov 26, 2025

To disclose

48 weeks

Affected

8state residents only

Linked

4 filings

Confidence

66%

Full breach record for Horizon Healthcare RCM →2 incidents on file

Horizon Healthcare RCM notified Montana residents of a ransomware incident discovered on December 27, 2024. Attackers encrypted files and exfiltrated data containing names and government IDs between Dec 26-27, 2024. Horizon restored systems, engaged Kroll for identity monitoring, and enhanced security measures.

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Incident timeline

undetected · 1 days

discovery → filing · 48 weeks / 334 days

Dec 26, 2024

Begins

Dec 27, 2024

Discovered

Nov 26, 2025

Filed

vs. sector median

+35 wks slower

This filing is one of 4 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (3) · sorted by filing gap

Vermont State AGbd_00ff9a47dfc272c42025-11-26Verified
Maine State AGbd_24c4025ca3ca22ff2025-11-26Candidate
New Hampshire State AGbd_ef67249e664d42272025-11-26Verified

Name: Horizon Healthcare RCM
norm: horizon healthcare rcm

Name: Horizon Healthcare RCM
norm: horizon healthcare rcm
Industry: HealthcarellmTechnologyllm

Discovered: Dec 27, 2024
Breach occurred: Dec 26, 2024 – Dec 27, 2024
Undetected for: 1 dayoccurrence → discovery
Materiality determined: —
Notification sent: —
Affected individuals: 8state-resident count only
Data types: Identity (basic)Government ID
Attack vector: Ransomware
MITRE ATT&CK: T1486 Data Encrypted for ImpactT1041 Exfiltration Over C2 Channel
Threat actor: ExternalFinancial

During the incident: Securely restored our systems
Arranged for the party responsible for this matter to delete the copied information
Providing notice of this event to individuals
Providing free resources and guidance
Implemented additional technical measures and processes to further enhance the company’s security
Changes made: Implemented additional technical measures and processes to further enhance the company’s security
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 48 weeks(334 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 4 filings · 4 states

View merged incident ↗

Vermont State AGNov 26 · first

Maine State AGNov 26 · first

New Hampshire State AGNov 26 · first

Montana State AGNov 26 · first · this page

Evidence ladder

Leak-site claim

Attacker assertion only. Establishes: claim date, group, alleged victim.

Press / market report

Unlocks: incident narrative, operational impact. Still no compliance clock.

State AG / regulator filingThis record

Unlocks: discovery date, data types, affected count, compliance clock.

SEC 8-K / victim statement

Unlocks: materiality, stated response, full audit trail. Ceiling removed.

Source URL: https://dojmt.gov/wp-content/uploads/2026/01/Consumer-notification-letter-18.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Nov 26, 2025
Raw hash: 997291eb90b47b64271ec40d3d84915a6997325eb69ae4a5d0c14e8e40517430

Linked disclosures

Regulatory filings (3) · sorted by filing gap

Reporting entityHorizon Healthcare RCM

Victim entityHorizon Healthcare RCM

Incidentdiscovered Dec 27, 2024

Stated responseSecurely restored our systems

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancedojmt.gov