MalwareHealthcareFinancial ServicesHealthcareRansomwareData ExfiltratedData EncryptedCustomer Data InvolvedIdentity (basic)LowContained

Horizon Healthcare RCM

bd_ef67249e664d4227 · schema v1 · pii pii-v1

Severity

Low

Discovered

Dec 27, 2024

Filed

Nov 26, 2025

To disclose

48 weeks

Affected

10state residents only

Linked

4 filings

Confidence

65%

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

Horizon Healthcare RCM, a revenue-cycle management provider, issued a supplemental data breach notice to the New Hampshire Attorney General on November 26, 2025. The incident involved a computer virus (ransomware) that encrypted files and resulted in unauthorized copying of patient data between December 26-27, 2024. Approximately 10 New Hampshire residents were affected. The breach involved names and other personal information. Horizon engaged Kroll for identity monitoring and implemented enhanced security measures.

J jump to incidentP pin to compareR raw source

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
Montana State AGbd_c5493de054e7d7522025-11-26Candidate

Name: Mullen Coughlin LLC
norm: mullen coughlin

Name: Horizon Healthcare RCM
norm: horizon healthcare rcm
Industry: HealthcarellmFinancial Servicesllm

Discovered: Dec 27, 2024
Breach occurred: Dec 26, 2024 – Dec 27, 2024
Undetected for: 1 dayoccurrence → discovery
Materiality determined: —
Notification sent: Nov 26, 2025
Affected individuals: 10state-resident count only
Data types: Identity (basic)
Attack vector: Ransomware
MITRE ATT&CK: T1486 Data Encrypted for ImpactT1041 Exfiltration Over C2 Channel
Threat actor: ExternalFinancial

During the incident: Arranged for the party responsible for this matter to delete the copied information
Provided notice of this event to individuals
Provided 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

Montana State AGNov 26 · first

New Hampshire 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://mm.nh.gov/files/uploads/doj/remote-docs/horizon-financial-management-20251126.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: 44f3ffeb6048af787e71ca804b3cd7c2dfb3b10cf922b5415c33386831e27282

Linked disclosures

Regulatory filings (3) · sorted by filing gap

Reporting entityMullen Coughlin LLC

Victim entityHorizon Healthcare RCM

Incidentdiscovered Dec 27, 2024

Stated responseArranged for the party responsible for this matter to delete the copied information

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov