HackingFinancial ServicesFinanceStolen CredentialsData ExfiltratedCustomer Data InvolvedIdentity (basic)Government IDFinancial accountMediumContained

MemberSource Credit Union

bd_1fa68433c68e2944 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Jun 3, 2025

Filed

May 5, 2026

To disclose

48 weeks

Affected

15state residents only

Linked

8 filings

Confidence

66%

Full breach record for MemberSource Credit Union →

MemberSource Credit Union notified Montana residents of a data event discovered on June 3, 2025. Unencrypted files containing names, SSNs, driver's licenses, and financial account info were taken from branch networks. The credit union reset passwords, reported to federal law enforcement, and offered 12 months of credit monitoring.

J jump to incidentP pin to compareR raw source

Incident timeline

discovery → filing · 48 weeks / 336 days

Jun 3, 2025

Discovered

May 5, 2026

Filed

vs. sector median

+39 wks slower

This filing is one of 8 about the same incident.View merged incident

Linked disclosures

Why this link?

Ransomware claims (1)

Leak Sitesafepaybd_b2fc6079fb9d7fa02025-06-03 · +336dVerified by operator

Regulatory filings (6) · sorted by filing gap

Nebraska State AGbd_1368db5c6ffe857e2026-05-07 · +2dVerified by operator
Indiana State AGbd_61c95d24c3f146972026-05-07 · +2dVerified
Massachusetts State AGbd_9aa063fac94e3ba32026-05-08 · +3dVerified
California State AGbd_9db84dbb566e334a2026-05-08 · +3dVerified

Show 2 more filings ↓up to 6d gap

Vermont State AGbd_c53f2485178b1a202026-05-08 · +3dVerified
Texas State AGbd_aa1e8bc975a47fba2026-05-11 · +6dVerified

Name: MemberSource Credit Union
norm: membersource credit union
Domain: membersourcecu.org

Name: MemberSource Credit Union
norm: membersource credit union
Domain: membersourcecu.org
Industry: Financial Servicesllm

Discovered: Jun 3, 2025
Materiality determined: —
Notification sent: May 7, 2026
Affected individuals: 15state-resident count only
Data types: Identity (basic)Government IDFinancial account
Data elements: Social Security number
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid AccountsT1041 Exfiltration Over C2 Channel
Threat actor: ExternalFinancial
Regulator citations: reported the incident to federal law enforcement
Initial access: valid_credentials

During the incident: Partnered with specialists to investigate the nature and scope of the event and restore our operations safely and securely
Reset user passwords
Reported the incident to federal law enforcement
Changes made: Reviewing our existing security controls, policies, and procedures we have in place to maximize the benefits of our encryption software
Providing you with access to Single Bureau Credit Monitoring/Single Bureau Credit Report/Single Bureau Credit Score services at no charge
Providing you with proactive fraud assistance
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 48 weeks(336 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 7 filings · 7 states

View merged incident ↗

Montana State AGMay 5 · first · this page

Nebraska State AG+2d

Indiana State AG+2d

Massachusetts State AG+3d

California State AG+3d

Vermont State AG+3d

Texas State AG+6d

Pattern: first filing May 5 (MT), last May 11 (TX) — 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://dojmt.gov/wp-content/uploads/2026/05/Consumer-notification-letter-9.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: May 5, 2026
Raw hash: 74404aca28c30e6a47ea5ffdcb4c5e672883b07328e623784a9e3f10ff454d84

Linked disclosures

Ransomware claims (1)

Regulatory filings (6) · sorted by filing gap

Reporting entityMemberSource Credit Union

Victim entityMemberSource Credit Union

Incidentdiscovered Jun 3, 2025

Stated responsePartnered with specialists to investigate the nature and scope of the event and restore our operations safely and securely

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancedojmt.gov