HackingProfessional ServicesProfessional ServicesStolen CredentialsData ExfiltratedCustomer Data InvolvedIdentity (basic)Government IDMediumContained

Cobblestone Opco, LLC

bd_a231eaa22fd9bc53 · schema v1 · pii pii-v2

Severity

Medium

Discovered

Jul 21, 2025

Filed

Sep 22, 2025

To disclose

—

Affected

3state residents only

Linked

3 filings

Confidence

66%

Cobblestone Opco, LLC notified Nebraska residents that an unknown individual accessed personal information (name and SSN) from specific email accounts between September 27, 2024, and January 24, 2025. Cobblestone discovered the breach on July 21, 2025, reset passwords, and notified 3 Nebraska residents on September 22, 2025. Response included employee retraining, credit monitoring via Epiq, and notifications to regulators and credit bureaus.

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Incident timeline

undetected · 297 days

Sep 27, 2024

Begins

Jul 21, 2025

Discovered

Sep 22, 2025

Filed

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

Linked disclosures

Why this link?

Regulatory filings (2) · sorted by filing gap

Massachusetts State AGbd_b98e4c6e1e3bf93f2025-09-22Verified
Indiana State AGbd_bb92434b31ab11102025-09-22Candidate

Name: Cobblestone Opco, LLC
norm: cobblestone opco
Domain: staycobblestone.com

Name: Cobblestone Opco, LLC
norm: cobblestone opco
Domain: staycobblestone.com
Industry: Professional Servicesllm

Discovered: Jul 21, 2025
Breach occurred: Sep 27, 2024 – Jan 24, 2025
Undetected for: 297 daysoccurrence → discovery
Materiality determined: —
Notification sent: Sep 22, 2025
Affected individuals: 3state-resident count only
Data types: Identity (basic)Government ID
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid Accounts
Threat actor: External
Regulator citations: Provided written notice of this event to relevant state regulators
Initial access: valid_credentials

During the incident: Reset of relevant passwords
Reviewed the affected accounts to understand what information was affected
Confirmed that its email environment was secure
Implemented additional measures to prevent unauthorized access
Retrained employees on email security
Sent a communication on how to identify and report a phishing email
Provided access to credit monitoring services for one (1) year, through Epiq
Provided potentially impacted individuals with guidance on how to better protect against identity theft and fraud
Provided written notice of this event to relevant state regulators
Provided written notice of this event to the three major credit reporting agencies, Equifax, Experian, and TransUnion
Changes made: Implemented additional security measures within the email environment
Completed a review of policies and procedures to prevent this from happening again
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 22 · first

Indiana State AGSep 22 · first

Nebraska State AGSep 22 · 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://nebraska.gov/ago/data-breach/documents/a6cb2907-9475-4fec-8283-8cdf2711e976.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Sep 22, 2025
Raw hash: a1f7590807c9569b4b797529e8c9f7eb4ce652812509dde7561e6fa9b76833e4

Linked disclosures

Regulatory filings (2) · sorted by filing gap

Reporting entityCobblestone Opco, LLC

Victim entityCobblestone Opco, LLC

Incidentdiscovered Jul 21, 2025

Stated responseReset of relevant passwords

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancenebraska.gov