HackingTelecom & MediaFinancial ServicesInformationStolen CredentialsSupply Chain (3P Vendor)Customer Data InvolvedData ExfiltratedIdentity (basic)Government IDHighContained

T-MOBILE USA, INC.

bd_ba0dd1171b8616bb · schema v1 · pii pii-v1

Severity

High

Discovered

Sep 15, 2015

Filed

Oct 1, 2015

To disclose

16 days

Affected

1,134state residents only

Linked

4 filings

Confidence

66%

Full breach record for T-MOBILE USA, INC. →22 incidents on file

T-Mobile USA, Inc. notified Montana AG that Experian, a third-party credit reporting service provider, experienced unauthorized access to servers containing T-Mobile customer data on September 15, 2015. Data included names, SSNs, DOBs, and IDs. Experian notified T-Mobile on Sept 21, 2015, and offered 2 years of credit monitoring.

J jump to incidentP pin to compareR raw source

Incident timeline

discovery → filing · 16 days

Sep 15, 2015

Discovered

Oct 1, 2015

Filed

This filing is one of 4 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (3) · sorted by filing gap

Massachusetts State AGbd_16201a335c3674ae2015-10-01Verified
California State AGbd_19093bdb9a9ec6d42015-10-01Verified
Massachusetts State AGbd_8f10059d4aee79f82015-11-04 · +34dCandidate

Name: Experian plc
norm: experian
Domain: experian.com

Name: T-MOBILE USA, INC.
norm: t mobile usa
Domain: t-mobile.com
Industry: Telecom & MediallmFinancial Servicesllm

Discovered: Sep 15, 2015
Materiality determined: —
Notification sent: Sep 21, 2015
Affected individuals: 1,134state-resident count only
Data types: Identity (basic)Government ID
Data elements: Date of birth
Attack vector: Third-Party / Supply Chain
MITRE ATT&CK: T1078 Valid AccountsT1041 Exfiltration Over C2 Channel
Threat actor: ExternalFinancial
Regulator citations: Notified appropriate federal, state and international law enforcement agencies
Third party: via Experian
Initial access: valid_credentials

During the incident: Began to investigate the incident
Implemented additional security measures
Notified appropriate federal, state and international law enforcement agencies
Took additional security steps to help prevent future incidents
Offering a complimentary two-year membership in ProtectMyID Elite credit monitoring and identity theft resolution services
Changes made: Implemented additional security measures
Took additional security steps to help prevent future incidents
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 16 days(16 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 4 filings · 3 states

View merged incident ↗

Massachusetts State AGOct 1 · first

California State AGOct 1 · first

Montana State AGOct 1 · first · this page

Massachusetts State AG+34d

Pattern: first filing Oct 1 (MA), last Nov 4 (MA) — a 34-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/T-Mobile-USA-Inc..pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Oct 1, 2015
Raw hash: d24d4aa7667d78150ace1ec3eeb62c868112b3162b15088804b4a416122e9a92

Linked disclosures

Regulatory filings (3) · sorted by filing gap

Reporting entityExperian plc

Victim entityT-MOBILE USA, INC.

Incidentdiscovered Sep 15, 2015

Stated responseBegan to investigate the incident

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancedojmt.gov