MalwareHealthcareHealthcareRansomwareData ExfiltratedData EncryptedRansom DemandedIdentity (basic)Government IDHealth (basic)Financial accountMediumContained

Horizon Behavioral Health

bd_225fc4e0b0d88793 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Mar 16, 2025

Filed

Apr 21, 2025

To disclose

5 weeks

Affected

Not disclosed

Linked

5 filings

Confidence

66%

Full breach record for Horizon Behavioral Health →

Horizon Behavioral Health disclosed a ransomware incident discovered on March 16, 2025, with activity starting around March 13, 2025. The breach impacted patient demographic data (SSN, DL), clinical information, and insurance claims. Horizon engaged forensic experts, notified the FBI and CISA, and provided complimentary identity monitoring to affected individuals.

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Vermont clock⏱ VT AG >14 bday5 weeks discovery → filing

⚠ unattributedNo provenance was recorded for this discovery date and it matches no other date on the record. It may be correct, but it is not independently grounded.

Incident timeline

undetected · 3 days

discovery → filing · 5 weeks / 36 days

Mar 13, 2025

Begins

Mar 16, 2025

Discovered

Apr 21, 2025

Filed

vs. sector median

7 wks faster

This filing is one of 5 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (4) · sorted by filing gap

Nebraska State AGbd_494ebdd5f2841ce42025-04-21Verified
HHS OCRbd_87431939e0eabf122025-04-21Candidate
Montana State AGbd_ba25fb5419d6a0062025-04-21Verified
Massachusetts State AGbd_c52606e3518997232025-04-21Verified

Name: Horizon Behavioral Health
norm: horizon behavioral health

Name: Horizon Behavioral Health
norm: horizon behavioral health
Industry: Healthcarellm

Discovered: Mar 16, 2025
Breach occurred: Mar 13, 2025 – Mar 16, 2025
Undetected for: 3 daysoccurrence → discovery
Materiality determined: —
Notification sent: Apr 21, 2025
Affected individuals: Not disclosed
Data types: Identity (basic)Government IDHealth (basic)Financial account
Data elements: Social Security numberDate of birthMedical information
Attack vector: Ransomware
MITRE ATT&CK: T1486 Data Encrypted for ImpactT1041 Exfiltration Over C2 Channel
Threat actor: ExternalFinancial
Regulator citations: Notified state and federal law enforcement, including the FBI’s Cyber Crimes Division, the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency (CISA), and the Cyber Fusion Center of the Virginia State Police

During the incident: Notified state and federal law enforcement, including the FBI’s Cyber Crimes Division, the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency (CISA), and the Cyber Fusion Center of the Virginia State Police
Engaged outside cybersecurity experts to investigate
Took steps to stop the ransomware
Arranged to provide complimentary identity monitoring for any individuals with data potentially implicated by this incident
Changes made: Reviewed system security and taken steps to increase that security going forward
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 5 weeks(36 days from discovery to filing)
Compliance flags: VT AG >14 bday
Discovery-date grounding: unattributedNo provenance was recorded for this discovery date and it matches no other date on the record. It may be correct, but it is not independently grounded.

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 5 filings · 5 states

View merged incident ↗

Nebraska State AGApr 21 · first

HHS OCRApr 21 · first

Montana State AGApr 21 · first

Massachusetts State AGApr 21 · first

Vermont State AGApr 21 · 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://ago.vermont.gov/document/2025-04-21-horizon-behavioral-health-data-breach-notice-consumers
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Apr 21, 2025
Raw hash: 68d4a5fdc5aec9e349d718359fb18dd21c1181a74aeab065e9c46f3b1a01064e

Linked disclosures

Regulatory filings (4) · sorted by filing gap

Reporting entityHorizon Behavioral Health

Victim entityHorizon Behavioral Health

Incidentdiscovered Mar 16, 2025

Stated responseNotified state and federal law enforcement, including the FBI’s Cyber Crimes Division, the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency (CISA), and the Cyber Fusion Center of the Virginia State Police

ComplianceVT AG >14 bday

Extraction provenanceno artifact recorded

Source provenanceago.vermont.gov