HackingHealthcareProfessional ServicesHealthcareStolen CredentialsTargetedData ExfiltratedPIIIdentity (basic)HighContained

MCBS, LLC

bd_bf3c11705b24a8a6 · schema v1 · pii pii-v1

Severity

High

Discovered

Sep 25, 2025

Filed

Jul 1, 2026

To disclose

40 weeks

Affected

301,809state residents only

Linked

7 filings

Confidence

64%

Full breach record for MCBS, LLC →2 incidents on file

MCBS, LLC, a medical billing services provider, notified South Carolina residents of a cybersecurity incident. Unauthorized access to its network occurred between September 22-26, 2025. The company discovered the breach on September 25, 2025, and confirmed unauthorized acquisition of personal information on May 28, 2026, following a forensic investigation. Affected data includes personal information. MCBS engaged external cybersecurity professionals and is offering complimentary identity protection services.

J jump to incidentP pin to compareR raw source

Leak gap clock✗ Leak >180d40 weeks discovery → filing

⚠ unattributedNo provenance was recorded for this discovery date and it matches no other date on the record. It may be correct, but it is not independently grounded.

Incident timeline

undetected · 3 days

discovery → filing · 40 weeks / 279 days

Sep 22, 2025

Begins

Sep 25, 2025

Discovered

Jul 1, 2026

Filed

vs. sector median

+27 wks slower

This filing is one of 7 about the same incident.View merged incident

A leak claim by pear about this victim predates this filing by 279 days.View originating leak claim

Linked disclosures

Why this link?

Ransomware claims (1)

Leak Sitepearbd_fbca2f8d470dced22025-09-25 · +279dVerified by operator

Regulatory filings (5) · sorted by filing gap

Illinois State AGbd_bf98d272641890612026-07-01Verified
Texas State AGbd_51bebdfc54a78a9b2026-06-30 · +1dVerified
New Hampshire State AGbd_8f3ea50c0a24e40c2026-06-29 · +2dVerified by operator
California State AGbd_32aaf81428502adc2026-06-26 · +5dVerified by operator

Show 1 more filing ↓up to 5d gap

HHS OCRbd_8ed31a4b32add53a2026-06-26 · +5dVerified by operator

Name: MCBS, LLC
norm: mcbs
Domain: mcbs.com

Name: MCBS, LLC
norm: mcbs
Domain: mcbs.com
Industry: HealthcarellmProfessional Servicesllm

Discovered: Sep 25, 2025
Breach occurred: Sep 22, 2025 – Sep 26, 2025
Undetected for: 3 daysoccurrence → discovery
Materiality determined: —
Notification sent: —
Affected individuals: 301,809state-resident count only
Data types: PIIIdentity (basic)
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid Accounts
Threat actor: External
Initial access: valid_credentials

During the incident: Commenced a prompt and thorough investigation
Working very closely with external cybersecurity professionals
Conducted an extensive forensic investigation and comprehensive document review
Providing complimentary access to identity protection services
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 40 weeks(279 days from discovery to filing)
Compliance flags: Leak >180dSC CRA notice due
Discovery-date grounding: unattributedNo provenance was recorded for this discovery date and it matches no other date on the record. It may be correct, but it is not independently grounded.

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 6 filings · 6 states

View merged incident ↗

California State AGJun 26 · first

HHS OCRJun 26 · first

New Hampshire State AG+3d

Texas State AG+4d

Illinois State AG+5d

South Carolina State AG+5d · this page

Pattern: first filing Jun 26 (CA), last Jul 1 (SC) — a 5-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://consumer.sc.gov/sites/consumer/files/Documents/Security%20Breach%20Notices/2026/Consumer%20Letter%20-%20MCBS%2C%20LLC.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jul 1, 2026
Raw hash: 9a339a5910d528f430aae8412ae20ef74efa966347d8bd77beab68a3e2bb2338

Linked disclosures

Ransomware claims (1)

Regulatory filings (5) · sorted by filing gap

Reporting entityMCBS, LLC

Victim entityMCBS, LLC

Incidentdiscovered Sep 25, 2025

Stated responseCommenced a prompt and thorough investigation

ComplianceLeak >180d

Extraction provenanceno artifact recorded

Source provenanceconsumer.sc.gov