WISCONSINMalwareHealthcareFinancial ServicesHealthcareRansomwareCapture Stored DataCustomer Data InvolvedData EncryptedRansom DemandedData ExfiltratedIdentity (basic)Government IDHealth (basic)CriticalContained

GROUP HEALTH COOPERATIVE OF SOUTH CENTRAL WISCONSIN

bd_453e14285276c3d3 · schema v1 · pii pii-v1

Severity

Critical

Discovered

—

Filed

Apr 8, 2024

To disclose

—

Affected

533,809

Linked

4 filings

Confidence

97%

Full breach record for GROUP HEALTH COOPERATIVE OF SOUTH CENTRAL WISCONSIN →

Group Health Cooperative of South Central Wisconsin (a Health Plan, WI) reported to HHS on 2024-04-08 a ransomware attack affecting 533,809 individuals. PHI on network servers was compromised, including names, Social Security numbers, addresses, dates of birth, and medical record numbers. The CE notified HHS, affected individuals, and the media, provided substitute notice and complimentary credit monitoring, and implemented additional administrative, technical, and security safeguards. Staff were retrained on PHI protection.

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HIPAA clock✓ HHS notified

⚠ no discovery dateNo discovery date was extracted, so no notification clock can be evaluated.

⚠ No discovery dateThe OCR public portal omits the discovery date, so the 60-day notification clock cannot be evaluated from this source — only that the filing was submitted.

Incident timeline — partial

? — ?

Breach window unknown

Apr 8, 2024

Filed

—

Corroborated · see linked filings

Compliance clocks stay unassessable until a regulatory filing lands. Dashed segments fill in automatically when corroboration arrives.

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

Massachusetts State AGbd_009d2e599b94c6382024-04-08Verified
Maine State AGbd_7d9f6fe2b75d08b82024-04-08Candidate
Wisconsin State AGbd_f89f7efae99505a42024-02-09 · +59dVerified by operator

Name: GROUP HEALTH COOPERATIVE OF SOUTH CENTRAL WISCONSIN
norm: group health cooperative of south central wisconsin
Industry: Insurance — Health

Name: GROUP HEALTH COOPERATIVE OF SOUTH CENTRAL WISCONSIN
norm: group health cooperative of south central wisconsin
Industry: Insurance — Health
Industry: Healthcaresource defaultFinancial Servicesllm

Discovered: Not extracted — the OCR public portal omits it
Materiality determined: —
Notification sent: —
Affected individuals: 533,809nationwide
Data types: Identity (basic)Government IDHealth (basic)
HHS breach type: Hacking / IT incident
Where the data lived: Network server
Covered-entity type: Health plan
Attack vector: Unauthorized Access
MITRE ATT&CK: T1486 Data Encrypted for ImpactT1041 Exfiltration Over C2 ChannelT1078 Valid Accounts
Threat actor: ExternalFinancial
Regulator citations: HHS OCR notified

During the incident: Notified affected individuals
Notified media
Provided substitute notice
Provided complimentary credit monitoring services to affected individuals
Implemented additional administrative, technical, and security safeguards
Retrained staff on requirements to protect and secure PHI
Changes made: Additional administrative safeguards implemented
Additional technical safeguards implemented
Additional security safeguards implemented
Staff retraining on PHI protection requirements
Source: Quoted from the filing itself, not independently verified.

Compliance flags: HHS notified
Discovery-date grounding: no discovery dateNo discovery date was extracted, so no notification clock can be evaluated.
Clock breakdown: Statute Window Elapsed Threshold Status
HIPAA
Discovered: not extracted
→ Notified: not extracted
— regulatory submission HHS notified

Statute	Window	Elapsed	Threshold	Status
HIPAA	Discovered: not extracted → Notified: not extracted	—	regulatory submission	HHS notified

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 4 filings · 3 states

View merged incident ↗

Wisconsin State AGFeb 9 · first

Massachusetts State AG+59d

Maine State AG+59d

HHS OCR+59d · this page

Pattern: first filing Feb 9 (WI), last Apr 8 (WI) — a 59-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://ocrportal.hhs.gov/ocr/breach/breach_report.jsf
DisclosureLens renders the full SEC/HHS filing inline below from the originating regulator’s public record (§4.5 fair report privilege).
Filed at: Apr 8, 2024
Raw hash: 04d96ce53f25ce8fa6e6de4288c14ecd962e372563052eb7d841159fa97f033b

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Linked disclosures

Regulatory filings (3) · sorted by filing gap

Reporting entityGROUP HEALTH COOPERATIVE OF SOUTH CENTRAL WISCONSIN

Victim entityGROUP HEALTH COOPERATIVE OF SOUTH CENTRAL WISCONSIN

IncidentUnauthorized Access

Stated responseNotified affected individuals

ComplianceHHS notified

Extraction provenanceno artifact recorded

Source provenanceocrportal.hhs.gov

Source filing