HackingHealthcareHealthcareSupply Chain (3P Vendor)Business Associate (HIPAA)Customer Data InvolvedDelayed DiscoveryPHIGovernment IDIdentity (basic)Health (basic)MediumContained

Westchester Ellenville Hospital d.b.a. Ellenville Regional Hospital

bd_15016353cb2d9edf · schema v1 · pii pii-v2

Severity

Medium

Discovered

Jun 26, 2026

Filed

Sep 1, 2026

To disclose

—

Affected

221state residents only

Linked

3 filings

Confidence

70%

Full breach record for Westchester Ellenville Hospital d.b.a. Ellenville Regional Hospital →

Westchester Ellenville Hospital d.b.a. Ellenville Regional Hospital notified the MA AG of a data security incident involving third-party vendor Aesto, LLC. Unauthorized access occurred between Dec 2, 2025, and Dec 18, 2025, in Aesto's AWS environment. ERH was notified on June 26, 2026. 221 Massachusetts residents were affected. Data exposed included names, SSNs, dates of birth, medical record numbers, and physician names. ERH offered 24 months of credit monitoring.

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Incident timeline

undetected · 206 days

Dec 2, 2025

Begins

Jun 26, 2026

Discovered

Sep 1, 2026

Filed

This filing is one of 3 filings about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (2) · sorted by filing gap

New Hampshire State AGbd_4cbd8aa41605a4482026-09-15 · +14dVerified
Indiana State AGbd_9d56991a1a3616772026-09-16 · +15dVerified

Name: Westchester Ellenville Hospital d.b.a. Ellenville Regional Hospital
norm: westchester ellenville hospital
Domain: wilsonelser.com

Name: Westchester Ellenville Hospital d.b.a. Ellenville Regional Hospital
norm: westchester ellenville hospital dba ellenville regional hospital
Also named: Westchester Ellenville Hospitaldba oflegal entity
Ellenville Regional Hospitaldba oftrade name
Industry: Healthcarellm

Discovered: Jun 26, 2026
Breach occurred: Dec 2, 2025 – Dec 18, 2025
Undetected for: 206 daysoccurrence → discovery
Materiality determined: —
Notification sent: Sep 16, 2026
Affected individuals: 221state-resident count only
Data types: PHIGovernment IDIdentity (basic)Health (basic)
Attack vector: Third-Party / Supply Chain
MITRE ATT&CK: T1078 Valid AccountsT1041 Exfiltration Over C2 Channel
Threat actor: External
Regulator citations: Notified Massachusetts Attorney GeneralAesto began providing regulatory notice to the Department of Health and Human Services on behalf of affected organizations
Third party: via Aesto, LLC

During the incident: Engaged legal counsel to help assess the situation
Requested additional information from Aesto
Provided individual notice to impacted individuals
Offered individuals complimentary credit monitoring and identity theft protection services by IDX for a period of twenty-four (24) months
Highlighted steps that individuals can take to protect themselves including actively monitoring their financial accounts and statements, requesting a free credit report, and placing a fraud alert or security freeze on their credit reports
Source: Quoted from the filing itself, not independently verified.

Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 3 filings · 3 states

View merged incident ↗

Massachusetts State AGSep 1 · first · this page

New Hampshire State AG+14d

Indiana State AG+15d

Pattern: first filing Sep 1 (MA), last Sep 16 (IN) — a 15-day rolling notification. Rolling spreads often mean counsel is filing as thresholds trip per state. Why this link?

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://www.mass.gov/doc/2026-1564-westchester-ellenville-hospital-dba-ellenville-regional-hospital/download
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Sep 1, 2026
Raw hash: b0920eb8ba5e903a58e4fc619f8c5a881f3552cf0d753be7714033b166a692e9

Linked disclosures

Regulatory filings (2) · sorted by filing gap

Reporting entityWestchester Ellenville Hospital d.b.a. Ellenville Regional Hospital

Victim entityWestchester Ellenville Hospital d.b.a. Ellenville Regional Hospital

Incidentdiscovered Jun 26, 2026

Stated responseEngaged legal counsel to help assess the situation

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancewww.mass.gov