HackingFinancial ServicesFinanceCustomer Data InvolvedPIIIdentity (basic)LowContained

Arch Underwriters Inc.

bd_8dfee8c841716b7c · schema v1 · pii pii-v2

Severity

Low

Discovered

Jul 1, 2026

Filed

Sep 1, 2026

To disclose

—

Affected

3state residents only

Confidence

67%

Full breach record for Arch Underwriters Inc. →

Arch Underwriters Inc. notified Massachusetts residents of unauthorized access to their personal information. The company became aware of suspicious activity on July 1, 2026, and determined that an unauthorized actor accessed files between June 30 and July 1, 2026. The incident involved potential exposure of personal information. The company engaged cybersecurity experts, terminated access, reported to law enforcement, and is offering 12 months of identity theft protection.

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Incident timeline

undetected · 1 days

Jun 30, 2026

Begins

Jul 1, 2026

Discovered

Sep 1, 2026

Filed

Tracked as a single-filing incident — the only disclosure on record for this event so far.Confirmed3 affectedView incident

Name: Arch Underwriters Inc.
norm: arch underwriters

Name: Arch Underwriters Inc.
norm: arch underwriters
Industry: Financial Servicesllm

Discovered: Jul 1, 2026
Breach occurred: Jun 30, 2026 – Jul 1, 2026
Undetected for: 1 dayoccurrence → discovery
Materiality determined: —
Notification sent: —
Affected individuals: 3state-resident count only
Data types: PIIIdentity (basic)
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid Accounts
Threat actor: External
Regulator citations: Reported the incident to law enforcement

During the incident: Initiated an investigation with our advisors
Took remediation steps to terminate the unauthorized access
Worked with leading cybersecurity experts to determine the nature and scope of the incident
Implemented additional processes to help prevent similar incidents from occurring in the future
Reported the incident to law enforcement
Offering complimentary access to Experian IdentityWorks for 12 months
Changes made: Implemented additional processes to help prevent similar incidents from occurring in the future
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.

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/2026-1678-arch-underwriters-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: 71f0b90983e1fb651078089cfae09a6e966989eeabcac376a17ed2ed988263f8

Reporting entityArch Underwriters Inc.

Victim entityArch Underwriters Inc.

Incidentdiscovered Jul 1, 2026

Stated responseInitiated an investigation with our advisors

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancewww.mass.gov