HackingFinancial ServicesFinanceCustomer Data InvolvedEmployee Data InvolvedData ExfiltratedIdentity (basic)Government IDMediumContained

The Middlefield Banking Company

bd_cc811a129570fcd5 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Apr 12, 2023

Filed

Dec 21, 2023

To disclose

36 weeks

Affected

Not disclosed

Linked

6 filings

Confidence

65%

Full breach record for The Middlefield Banking Company →2 incidents on file

The Middlefield Banking Company experienced a data security incident on April 12, 2023, where an unauthorized actor accessed systems between April 11-12, 2023. The actor acquired files containing names, dates of birth, and passport numbers of employees and customers. The bank engaged outside specialists, notified federal law enforcement, and implemented enhanced security controls. Affected individuals were offered 12 months of credit monitoring.

J jump to incidentP pin to compareR raw source

California clockDiscovered Apr 12, 2023 → Notified Dec 21, 2023253d ✗ CA 60-day late36 weeks discovery → filing

Incident timeline

undetected · 1 days

discovery → filing · 36 weeks / 253 days

Apr 11, 2023

Begins

Apr 12, 2023

Discovered

Dec 21, 2023

Filed

vs. sector median

+28 wks slower

This filing is one of 6 filings about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (5) · sorted by filing gap

Vermont State AGbd_2dee8d0f47f231bc2023-12-21Verified
Montana State AGbd_4752d46a27914d1a2023-12-21Candidate
New Hampshire State AGbd_719ea19c8e0056802023-12-21Verified
Massachusetts State AGbd_c1b3763023b7f8a72023-12-21Verified

Show 1 more filing ↓

SEC 8-Kbd_d3345e13b9cb6e072023-12-21Verified

Name: The Middlefield Banking Company
norm: the middlefield banking

Name: The Middlefield Banking Company
norm: the middlefield banking
Industry: Financial Servicesllm

Discovered: Apr 12, 2023
Breach occurred: Apr 11, 2023 – Apr 12, 2023
Undetected for: 1 dayoccurrence → discovery
Materiality determined: —
Notification sent: Dec 21, 2023
Affected individuals: Not disclosed
Data types: Identity (basic)Government ID
Data elements: Date of birth
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid Accounts
Threat actor: External
Regulator citations: Correspondence with federal law enforcement authorities

During the incident: Launched an investigation with the assistance of outside specialists
Prompt and continued correspondence with federal law enforcement authorities
Reviewed existing policies and procedures relating to data protection and security
Implemented enhanced security controls
Providing 12 months of complimentary access to credit monitoring and identity restoration services by Cyberscout through Identity Force
Changes made: Implemented enhanced security controls
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 36 weeks(253 days from discovery to filing)
Compliance flags: CA 60-day late · 253d
Discovery-date grounding: letter-groundedThe discovery date is the detection date narrated in the notification letter — the defensible tier.
Clock breakdown: Statute Window Elapsed Threshold Status
California
Discovered: Apr 12, 2023
→ Notified: Dec 21, 2023
253d 60 days (analyst band, pre-2026 discoveries) CA 60-day late

Statute	Window	Elapsed	Threshold	Status
California	Discovered: Apr 12, 2023 → Notified: Dec 21, 2023	253d	60 days (analyst band, pre-2026 discoveries)	CA 60-day late

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 6 filings · 5 states

View merged incident ↗

Vermont State AGDec 21 · first

Montana State AGDec 21 · first

New Hampshire State AGDec 21 · first

Massachusetts State AGDec 21 · first

SEC 8-KDec 21 · first

California State AGDec 21 · first · this page

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://oag.ca.gov/ecrime/databreach/reports/sb24-578344
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Dec 21, 2023
Raw hash: 6aeebc7ad78f931c501b42e4bfcc941d1532471084973a8ce92de0ba563a77af

Linked disclosures

Regulatory filings (5) · sorted by filing gap

Reporting entityThe Middlefield Banking Company

Victim entityThe Middlefield Banking Company

Incidentdiscovered Apr 12, 2023

Stated responseLaunched an investigation with the assistance of outside specialists

ComplianceCA 60-day late

Extraction provenanceno artifact recorded

Source provenanceoag.ca.gov