HackingProfessional ServicesProfessional ServicesStolen CredentialsData ExfiltratedCustomer Data InvolvedIdentity (basic)Government IDFinancial accountMediumContained

Hallisey & D'Agostino, LLP

bd_6d1636b0677487b4 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Oct 21, 2025

Filed

Apr 17, 2026

To disclose

25 weeks

Affected

981state residents only

Linked

5 filings

Confidence

66%

Full breach record for Hallisey & D'Agostino, LLP →

Hallisey & D’Agostino, LLP, a tax and accounting firm, reported a cybersecurity incident to the New Hampshire Attorney General on April 17, 2026. Unauthorized access occurred between September 28 and October 22, 2025. The breach potentially exposed names, Social Security numbers, driver's license numbers, and financial account information of 981 New Hampshire residents. The firm engaged forensic experts, notified the FBI, and offered 12 months of credit monitoring and identity theft protection services to affected individuals.

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Incident timeline

undetected · 23 days

discovery → filing · 25 weeks / 178 days

Sep 28, 2025

Begins

Oct 21, 2025

Discovered

Apr 17, 2026

Filed

vs. sector median

+7 wks slower

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

Linked disclosures

Why this link?

Regulatory filings (4) · sorted by filing gap

Indiana State AGbd_647dbf9a138be25b2026-04-17Candidate
Maine State AGbd_f2f9d2090f5cd0f32026-04-17Verified
Massachusetts State AGbd_65ace7cdc7cab0b12026-04-18 · +1dVerified
Vermont State AGbd_ee948235b7ce7dac2026-04-18 · +1dVerified

Name: Constangy, Brooks, Smith & Prophete, LLP
norm: constangy brooks smith prophete

Name: Hallisey & D'Agostino, LLP
norm: hallisey d agostino
Domain: hdllpcpa.com
Industry: Professional Servicesllm

Discovered: Oct 21, 2025
Breach occurred: Sep 28, 2025 – Oct 22, 2025
Undetected for: 23 daysoccurrence → discovery
Materiality determined: —
Notification sent: Apr 17, 2026
Affected individuals: 981state-resident count only
Data types: Identity (basic)Government IDFinancial account
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid Accounts
Threat actor: External
Regulator citations: Notified New Hampshire Attorney General
Initial access: valid_credentials

During the incident: Retained cybersecurity experts and launched a forensics investigation
Implemented additional security measures to further harden its environment
Notified the Federal Bureau of Investigation and will provide whatever cooperation is necessary to hold the perpetrator(s) of the incident accountable
Notified the affected individuals via first class U.S. mail
Offered recipients the ability to enroll in complimentary identity protection services through IDX
Changes made: Implemented enhanced security measures to help prevent a similar incident from occurring in the future
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 25 weeks(178 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 5 filings · 5 states

View merged incident ↗

Indiana State AGApr 17 · first

Maine State AGApr 17 · first

New Hampshire State AGApr 17 · first · this page

Massachusetts State AG+1d

Vermont State AG+1d

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/hallisey-d-agostino-20260417.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Apr 17, 2026
Raw hash: ecffc1c55782c706565ad405a8e16c631789299bf4585450d80946651b6c11e6

Linked disclosures

Regulatory filings (4) · sorted by filing gap

Reporting entityConstangy, Brooks, Smith & Prophete, LLP

Victim entityHallisey & D'Agostino, LLP

Incidentdiscovered Oct 21, 2025

Stated responseRetained cybersecurity experts and launched a forensics investigation

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov