HackingHealthcareHealthcareStolen CredentialsCustomer Data InvolvedTargetedPIIPHIIdentity (basic)LowContained

Sierra Vista Hospital & Clinics

bd_1f24d3d9561cf6f3 · schema v1 · pii pii-v1

Severity

Low

Discovered

Jan 29, 2025

Filed

Oct 8, 2025

To disclose

36 weeks

Affected

14state residents only

Linked

6 filings

Confidence

66%

Full breach record for Sierra Vista Hospital & Clinics →

Sierra Vista Hospital & Clinics notified Montana residents of a cybersecurity incident detected on January 29, 2025. Unauthorized access occurred between Jan 14-31, 2025, potentially exposing PII and PHI. The organization secured its network, engaged external forensic experts, and is offering complimentary credit monitoring via Experian.

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Incident timeline

undetected · 15 days

discovery → filing · 36 weeks / 252 days

Jan 14, 2025

Begins

Jan 29, 2025

Discovered

Oct 8, 2025

Filed

vs. sector median

+25 wks slower

This filing is one of 6 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (5) · sorted by filing gap

Massachusetts State AGbd_316f34b8c14802c12025-10-07 · +1dVerified
Texas State AGbd_98e33e96be702bb62025-10-07 · +1dVerified
New Hampshire State AGbd_46d90a4b9876e76f2025-10-10 · +2dVerified
HHS OCRbd_c1f6fbbed29347c22025-10-06 · +2dVerified

Show 1 more filing ↓up to 7d gap

Illinois State AGbd_f8afe2f84d5db6b52025-10-01 · +7dCandidate

Name: Sierra Vista Hospital & Clinics
norm: sierra vista hospital clinics

Name: Sierra Vista Hospital & Clinics
norm: sierra vista hospital clinics
Industry: Healthcarellm

Discovered: Jan 29, 2025
Breach occurred: Jan 14, 2025 – Jan 31, 2025
Undetected for: 15 daysoccurrence → discovery
Materiality determined: —
Notification sent: —
Affected individuals: 14state-resident count only
Data types: PIIPHIIdentity (basic)
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid AccountsT1119 Automated Collection
Threat actor: External
Initial access: valid_credentials

During the incident: Secured our network
Commenced a prompt and thorough investigation
Working very closely with external cybersecurity professionals
Conducted a thorough review of the potentially impacted data
Strengthened our network
Implemented additional security improvements recommended by third-party cyber security experts
Increased email filtering
Added additional malware monitoring
Added additional cybersecurity training for our employees
Offering complimentary access to Experian IdentityWorks
Changes made: Strengthened our network
Implemented additional security improvements recommended by third-party cyber security experts
Increased email filtering
Added additional malware monitoring
Added additional cybersecurity training for our employees
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 36 weeks(252 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 6 filings · 6 states

View merged incident ↗

Illinois State AGOct 1 · first

HHS OCR+5d

Massachusetts State AG+6d

Texas State AG+6d

Montana State AG+7d · this page

New Hampshire State AG+9d

Pattern: first filing Oct 1 (IL), last Oct 10 (NH) — a 9-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://dojmt.gov/wp-content/uploads/2026/05/Consumer-notification-letter-13.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Oct 8, 2025
Raw hash: 77ff610e44cd9fb452dc718f39ba8e666f82f4c68a5627df712a5115faf9e358

Linked disclosures

Regulatory filings (5) · sorted by filing gap

Reporting entitySierra Vista Hospital & Clinics

Victim entitySierra Vista Hospital & Clinics

Incidentdiscovered Jan 29, 2025

Stated responseSecured our network

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancedojmt.gov