MalwareEducationEducationRansomwareData EncryptedData ExfiltratedCustomer Data InvolvedIdentity (basic)LowContained

Mastery Charter High School

bd_e77dfb9a7798647d · schema v1 · pii pii-v1

Severity

Low

Discovered

Sep 15, 2024

Filed

Jun 12, 2025

To disclose

39 weeks

Affected

5state residents only

Linked

4 filings

Confidence

67%

Full breach record for Mastery Charter High School →2 incidents on file

Mastery Charter High School detected malicious encryption (ransomware) on September 15, 2024. An unauthorized actor downloaded data, including personal information (names) of five New Hampshire residents. The school shut down systems, engaged cybersecurity professionals, and notified federal law enforcement. Affected individuals are offered complimentary credit monitoring.

J jump to incidentP pin to compareR raw source

Incident timeline

discovery → filing · 39 weeks / 270 days

Sep 15, 2024

Discovered

Jun 12, 2025

Filed

vs. sector median

+30 wks slower

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

Indiana State AGbd_557cf3225408f29a2025-06-06 · +6dVerified
Vermont State AGbd_ac760a429f740ea32025-06-06 · +6dVerified
Maine State AGbd_d445c07723535b6b2025-06-06 · +6dCandidate

Name: Mastery Charter High School
norm: mastery charter high school

Name: Mastery Charter High School
norm: mastery charter high school
Industry: Educationllm

Discovered: Sep 15, 2024
Materiality determined: —
Notification sent: Jun 6, 2025
Affected individuals: 5state-resident count only
Data types: Identity (basic)
Attack vector: Ransomware
MITRE ATT&CK: T1486 Data Encrypted for ImpactT1041 Exfiltration Over C2 Channel
Threat actor: External
Regulator citations: Reporting the matter to federal law enforcementReporting this Incident to relevant government agencies

During the incident: Shutting down systems proactively
Reporting the matter to federal law enforcement
Engaging experienced cybersecurity professionals to assist
Providing written notification via regular mail to the impacted residents
Making information available on its website
Changes made: Expanding current use of multifactor authentication
Implementing additional endpoint detection and response monitoring
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 39 weeks(270 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 4 filings · 4 states

View merged incident ↗

Indiana State AGJun 6 · first

Vermont State AGJun 6 · first

Maine State AGJun 6 · first

New Hampshire State AG+6d · this page

Pattern: first filing Jun 6 (IN), last Jun 12 (NH) — a 6-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/mastery-charter-high-school-20250612.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jun 12, 2025
Raw hash: 99b18bcd246a1fb7c7fc5bdd483807515ea769665c584343e2baf60bf320833d

Linked disclosures

Regulatory filings (3) · sorted by filing gap

Reporting entityMastery Charter High School

Victim entityMastery Charter High School

Incidentdiscovered Sep 15, 2024

Stated responseShutting down systems proactively

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov