HackingFinancial ServicesFinanceStolen CredentialsData ExfiltratedCustomer Data InvolvedFinancial accountPIILowContained

Main Street Bank

bd_b93d9328210f7463 · schema v1 · pii pii-v1

Severity

Low

Discovered

May 18, 2025

Filed

Jun 1, 2026

To disclose

13 months

Affected

Not disclosed

Linked

2 filings

Confidence

66%

Full breach record for Main Street Bank →208 incidents on file

Main Street Bank notified Massachusetts customers that payment card data (names, numbers, expiration dates) was exposed after being recovered from the 'Black Stash Market' dark web marketplace on May 18, 2025. The bank stated its systems were not compromised and no SSNs or account numbers were accessed. Customers were offered new debit cards and credit monitoring advice.

J jump to incidentP pin to compareR raw source

Massachusetts clock✗ MA AG >90d13 months discovery → filing

⚠ occurrence dateThe stored discovery date equals the breach OCCURRENCE date. Detection is normally later, so this OVERSTATES the delay — a 'late' verdict here may not be real.

Incident timeline

discovery → filing · 13 months / 379 days

May 18, 2025

Begins

May 18, 2025

Discovered

Jun 1, 2026

Filed

vs. sector median

+46 wks slower

This filing is one of 2 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (1) · sorted by filing gap

Massachusetts State AGbd_4fed9b3bd1a49d032026-06-12 · +11dCandidate

Name: Main Street Bank
norm: main street bank

Name: Main Street Bank
norm: main street bank
Industry: Financial Servicesllm

Discovered: May 18, 2025
Breach occurred: May 18, 2025
Undetected for: 0 daysoccurrence → discovery
Materiality determined: —
Notification sent: May 28, 2026
Affected individuals: Not disclosed
Data types: Financial accountPII
Attack vector: Third-Party / Supply Chain
MITRE ATT&CK: T1563 Exploit Remote Assets
Threat actor: ExternalFinancial

During the incident: Offered customers the option to obtain an Instant Issued card or a new MSB debit card mailed in 10-12 business days
Advised customers to review account statements for suspicious activity
Encouraged use of Internet Banking to monitor account activity
Advised customers to contact credit reporting agencies (Experian, Equifax, TransUnion) to place fraud alerts or security freezes
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 13 months(379 days from discovery to filing)
Compliance flags: MA AG >90d
Discovery-date grounding: occurrence dateThe stored discovery date equals the breach OCCURRENCE date. Detection is normally later, so this OVERSTATES the delay — a 'late' verdict here may not be real.

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 2 filings

View merged incident ↗

Massachusetts State AGJun 1 · first · this page

Massachusetts State AG+11d

Pattern: first filing Jun 1 (MA), last Jun 12 (MA) — a 11-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/2026-884-main-street-bank/download
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jun 1, 2026
Raw hash: bb9d0afac5df3f68917851ec928df2875fc0e48d6a1dfe2e5b8773d121dad1ac

Linked disclosures

Regulatory filings (1) · sorted by filing gap

Reporting entityMain Street Bank

Victim entityMain Street Bank

Incidentdiscovered May 18, 2025

Stated responseOffered customers the option to obtain an Instant Issued card or a new MSB debit card mailed in 10-12 business days

ComplianceMA AG >90d

Extraction provenanceno artifact recorded

Source provenancewww.mass.gov