HackingHealthcareHealthcareStolen CredentialsCustomer Data InvolvedData ExfiltratedPIIPHIIdentity (basic)Government IDFinancial accountFinancial credentialsHealth (basic)MediumActive

Mainline Health Systems Inc

bd_261065496c6ad4cb · schema v1 · pii pii-v1

Severity

Medium

Discovered

May 21, 2025

Filed

Jun 24, 2025

To disclose

5 weeks

Affected

1state residents only

Linked

6 filings

Confidence

66%

Full breach record for Mainline Health Systems Inc →

Mainline Health Systems Inc reported an unauthorized access incident occurring on or about April 10, 2024, discovered on May 21, 2025. The breach impacted approximately one New Hampshire resident, exposing PII, PHI, SSNs, financial account data, and medical records. Mainline notified law enforcement, engaged cybersecurity experts, and is offering credit monitoring services. The investigation is ongoing.

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Incident timeline

undetected · 406 days

discovery → filing · 5 weeks / 34 days

Apr 10, 2024

Begins

May 21, 2025

Discovered

Jun 24, 2025

Filed

vs. sector median

8 wks faster

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

HHS OCRbd_2f3a0de1cd17c2742025-06-23 · +1dVerified
Massachusetts State AGbd_8f8d9fb358c4917b2025-06-23 · +1dVerified
Maine State AGbd_f84aac6a930bd29b2025-06-23 · +1dVerified
Nebraska State AGbd_a8b640e79c6460072025-06-20 · +4dVerified

Show 1 more filing ↓up to 6d gap

Texas State AGbd_4b8f3ae79ac45cb02025-06-30 · +6dVerified

Name: Mainline Health Systems Inc
norm: mainline health

Name: Mainline Health Systems Inc
norm: mainline health
Industry: Healthcarellm

Discovered: May 21, 2025
Breach occurred: Apr 10, 2024
Undetected for: 406 daysoccurrence → discovery
Materiality determined: —
Notification sent: Jun 20, 2025
Affected individuals: 1state-resident count only
Data types: PIIPHIIdentity (basic)Government IDFinancial accountFinancial credentialsHealth (basic)
Data elements: Social Security numberDate of birthMedical information
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid AccountsT1119 Automated Collection
Threat actor: ExternalFinancial
Regulator citations: Notified Attorney General John Formella
Initial access: valid_credentials

During the incident: Notified federal law enforcement of the incident
Engaged external cybersecurity professionals
Conducted a manual review
Providing notice to the affected individuals
Providing complimentary credit monitoring services
Changes made: Reviewing its existing policies and training protocols relating to data protection
Enhancing security measures and monitoring tools
Continually evaluate and modify practices and internal controls to enhance the security and privacy of protected personal information
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 5 weeks(34 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 ↗

Nebraska State AGJun 20 · first

HHS OCR+3d

Massachusetts State AG+3d

Maine State AG+3d

New Hampshire State AG+4d · this page

Texas State AG+10d

Pattern: first filing Jun 20 (NE), last Jun 30 (TX) — a 10-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://mm.nh.gov/files/uploads/doj/remote-docs/mainline-health-systems-20250624.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jun 24, 2025
Raw hash: e6819eaecc5a46e0080ad195905ecd8046f6c6a7e6c8c9f048c1692412ef80c4

Linked disclosures

Regulatory filings (5) · sorted by filing gap

Reporting entityMainline Health Systems Inc

Victim entityMainline Health Systems Inc

Incidentdiscovered May 21, 2025

Stated responseNotified federal law enforcement of the incident

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov