---
title: "AT&T security incident"
description: "What the retained public evidence establishes about the AT&T incident, its attack path, impact, and response."
incident_type: "Cybersecurity incident"
status: "active"
last_modified: "2026-09-19"
canonical_url: "https://www.ally.security/incidents/at-and-t-security-incident-2024"
markdown_url: "https://www.ally.security/incidents/at-and-t-security-incident-2024.md"
stix_url: "https://www.ally.security/incidents/at-and-t-security-incident-2024/stix.json"
---

# AT&T security incident

The retained public source describes the AT&T incident as Stolen credentials were used against a Snowflake customer account that did not enforce MFA. Other material details remain unresolved.

Last modified Sep 19, 2026 · 1 source

## Summary

- **Environment:** Telecom
- **Operational impact:** The reviewed source does not establish a precise operational or data impact
- **Financial impact:** No financial figure is established by the reviewed source evidence

## What happened

In 2024, AT\&T experienced an incident in its telecom environment. The retained source describes the attack path as follows: Stolen credentials were used against a Snowflake customer account that did not enforce MFA. [1](#source-1)

## Impact

- The reviewed source does not establish a precise affected-person count, data scope, or operational consequence.
- No financial loss, ransom amount, recovery cost, or regulatory penalty is established by the reviewed source evidence.

## Threat Group & Attack Vector

The retained source describes the attack path as follows: Stolen credentials were used against a Snowflake customer account that did not enforce MFA. The canonical record does not add intrusion steps beyond those supported by the source. [1](#source-1)

### Actors

- No threat actor group has been identified in the reviewed public evidence.

### TTPs

- [T1078 — Valid Accounts](https://attack.mitre.org/techniques/T1078/) — mapped from the cited behavior. [1](#source-1)

## Response

The retained source reports coordination with law enforcement as part of the incident response. [1](#source-1)
The retained source describes a forensic or specialist investigation of the incident. [1](#source-1)

This account is bounded to [AT\&T Form 8-K](https://www.sec.gov/Archives/edgar/data/732717/000073271724000046/t-20240506.htm). Details absent from that evidence are left unresolved rather than inferred. [1](#source-1)

## Assets

[Download the case-scoped STIX 2.1 bundle](<https://www.ally.security/incidents/at-and-t-security-incident-2024/stix.json>)

## Sources

Primary source records used to research this incident.

<a id="source-1"></a>

### AT&T Form 8-K

regulatory · U.S. Securities and Exchange Commission

<https://www.sec.gov/Archives/edgar/data/732717/000073271724000046/t-20240506.htm>

<details>
<summary>Evidence ledger</summary>

Review the supporting structured claims.

1. **Resulted In · 82% confidence · current**  
   AT&T security incident: Stolen credentials were used against a Snowflake customer account that did not enforce MFA.
2. **Resulted In · 90% confidence · current**  
   AT&T security incident: The retained source reports coordination with law enforcement as part of the incident response.
3. **Resulted In · 100% confidence · current**  
   AT&T security incident: The reviewed source documents the at&t security incident involving AT&T.
4. **Used Attack Technique · 90% confidence · current**  
   AT&T security incident: https://attack.mitre.org/techniques/T1078/
5. **Resulted In · 90% confidence · current**  
   AT&T security incident: The retained source describes a forensic or specialist investigation of the incident.
6. **Affected Organization · 100% confidence · current**  
   AT&T security incident: AT&T

</details>