HackingTelecom & MediaInformationStolen CredentialsPhishingData ExfiltratedCustomer Data InvolvedDelayed DiscoveryIdentity (basic)Government IDFinancial accountCredentialsHighContained

U.S. Cellular Corporation

bd_7cb9457bce354133 · schema v1 · pii pii-v1

Severity

High

Discovered

Jun 27, 2017

Filed

Oct 24, 2017

To disclose

17 weeks

Affected · nationwide

1,85262 in this filing

Linked

2 filings

Confidence

66%

U.S. Cellular filed a supplemental notice with the New Hampshire AG regarding a credential stuffing attack starting in April 2017. The incident exposed customer names, addresses, phone numbers, SSNs, and ACH/bank account data. Approximately 1,852 customers were affected, including 62 in NH. U.S. Cellular reset passwords, disabled accounts for former customers, and offered 12 months of credit monitoring.

J jump to incidentP pin to compareR raw source

Incident timeline

undetected · 87 days

discovery → filing · 17 weeks / 119 days

Apr 1, 2017

Begins

Jun 27, 2017

Discovered

Oct 24, 2017

Filed

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_77bc7ae00b5b548e2017-10-24Verified

Name: U.S. Cellular Corporation
norm: us cellular
Domain: uscellular.com

Name: U.S. Cellular Corporation
norm: us cellular
Domain: uscellular.com
Industry: Telecom & Mediallm

Discovered: Jun 27, 2017
Breach occurred: Apr 1, 2017
Undetected for: 87 daysoccurrence → discovery
Materiality determined: —
Notification sent: Oct 24, 2017
Affected individuals: 1,852state + nationwide
Data types: Identity (basic)Government IDFinancial accountCredentials
Data elements: Social Security number
Attack vector: Unauthorized Access
MITRE ATT&CK: T1110 Brute ForceT1078 Valid AccountsT1114 Email Collection
Threat actor: ExternalFinancial
Regulator citations: Reported the incident to law enforcement in accordance with the requirements of the Federal Communications Commission as well as certain state agencies
Initial access: valid_credentials

During the incident: Expired customer passwords
Disabled My Account for former customers
Introduced additional technical controls to protect My Account
Reported the incident to law enforcement
Offered 12 months of credit monitoring services
Changes made: Introduced additional technical controls to protect My Account from unauthorized access
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 17 weeks(119 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 2 filings · 2 states

View merged incident ↗

Massachusetts State AGOct 24 · first

New Hampshire State AGOct 24 · 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://mm.nh.gov/files/uploads/doj/remote-docs/us-cellular-20171024.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Oct 24, 2017
Raw hash: ed60a772b99646a5811db7dcf950600071903974b5e8b8631b7b019b734c413d

Linked disclosures

Regulatory filings (1) · sorted by filing gap

Reporting entityU.S. Cellular Corporation

Victim entityU.S. Cellular Corporation

Incidentdiscovered Jun 27, 2017

Stated responseExpired customer passwords

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov