HackingProfessional ServicesProfessional ServicesData ExfiltratedCustomer Data InvolvedIdentity (basic)LowContained

CornerStone Staffing Solutions, Inc.

bd_22dd62acb7c5bd85 · schema v1 · pii pii-v2

Severity

Low

Discovered

Nov 17, 2025

Filed

Sep 1, 2026

To disclose

—

Affected

Not disclosed

Linked

5 filings

Confidence

66%

Full breach record for CornerStone Staffing Solutions, Inc. →

Cornerstone Staffing Solutions, Inc. detected anomalous activity on November 17, 2025, indicating unauthorized access to its network between November 6 and 21, 2025. An investigation found indications that some data may have been removed, though specific files were not determined. Affected data types include name and potentially other personal information. The company engaged a third-party cybersecurity firm, contained the threat, and is offering credit monitoring services.

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Leak gap clock✗ Leak >180d

Incident timeline

undetected · 11 days

Nov 6, 2025

Begins

Nov 17, 2025

Discovered

Sep 1, 2026

Filed

This filing is one of 5 about the same incident.View merged incident

A leak claim by qilin about this victim predates this filing by 291 days.View originating leak claim

Linked disclosures

Why this link?

Ransomware claims (1)

Leak Siteqilinbd_ec840b7d9ffbec102025-11-13 · +292dVerified by operator

Regulatory filings (3) · sorted by filing gap

California State AGbd_e4dfd8c0234818a12026-09-11 · +10dVerified
Vermont State AGbd_29de5dbb97b766ee2026-09-12 · +11dVerified
Texas State AGbd_d3cf7d86357026862026-09-15 · +14dVerified by operator

Name: CornerStone Staffing Solutions, Inc.
norm: cornerstone staffing
Domain: cornerstone-staffing.com

Name: CornerStone Staffing Solutions, Inc.
norm: cornerstone staffing
Domain: cornerstone-staffing.com
Industry: Professional Servicesllm

Discovered: Nov 17, 2025
Breach occurred: Nov 6, 2025 – Nov 21, 2025
Undetected for: 11 daysoccurrence → discovery
Materiality determined: —
Notification sent: Sep 11, 2026
Affected individuals: Not disclosed
Data types: Identity (basic)
Attack vector: Unknown
MITRE ATT&CK: T1041 Exfiltration Over C2 Channel
Threat actor: External

During the incident: Launched an internal investigation
Engaged a third-party cybersecurity firm to contain the threat, support the investigation, and determine the scope of the unauthorized access
Implemented additional security measures
Changes made: Continuing to evaluate ways to further enhance the security of its environment to minimize the likelihood of similar events occurring in the future
Offering complimentary credit monitoring and identity protection services through HaystackID
Source: Quoted from the filing itself, not independently verified.

Compliance flags: Leak >180d
Discovery-date grounding: letter-groundedThe discovery date is the detection date narrated in the notification letter — the defensible tier.

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 4 filings · 4 states

View merged incident ↗

Massachusetts State AGSep 1 · first · this page

California State AG+10d

Vermont State AG+11d

Texas State AG+14d

Pattern: first filing Sep 1 (MA), last Sep 15 (TX) — a 14-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/2026-1536-cornerstone-staffing-solutions-inc/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: b53832e95e989763851fff7836c27ec06641512f2263cc970a2da654e625df61

Linked disclosures

Ransomware claims (1)

Regulatory filings (3) · sorted by filing gap

Reporting entityCornerStone Staffing Solutions, Inc.

Victim entityCornerStone Staffing Solutions, Inc.

Incidentdiscovered Nov 17, 2025

Stated responseLaunched an internal investigation

ComplianceLeak >180d

Extraction provenanceno artifact recorded

Source provenancewww.mass.gov