---
title: "Mailchimp security incident"
description: "What the retained public evidence establishes about the Mailchimp 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/mailchimp-security-incident-2022"
markdown_url: "https://www.ally.security/incidents/mailchimp-security-incident-2022.md"
stix_url: "https://www.ally.security/incidents/mailchimp-security-incident-2022/stix.json"
---

# Mailchimp security incident

Social engineering of internal support tool (0ktapus-adjacent). Used to target crypto customers' mailing lists.

Last modified Sep 19, 2026 · 1 source

## Summary

- **Environment:** Email marketing
- **Operational impact:** Used to target crypto customers' mailing lists
- **Financial impact:** No financial figure is established by the reviewed source evidence

## What happened

In 2022, Mailchimp experienced an incident in its email marketing environment. The retained source describes the attack path as follows: Social engineering of internal support tool (0ktapus-adjacent). [1](#source-1)

The documented consequence was: Used to target crypto customers' mailing lists. [1](#source-1)

## Impact

- Documented impact: Used to target crypto customers' mailing lists. [1](#source-1)
- 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: Social engineering of internal support tool (0ktapus-adjacent). The canonical record does not add intrusion steps beyond those supported by the source. [1](#source-1)

### Actors

- **0ktapus** — identified in the supported attack description. [1](#source-1)

### TTPs

- No specific MITRE ATT\&CK technique is currently mapped for this case.

## Response

The reviewed source does not describe containment, notification, or restoration steps in enough detail to summarize them responsibly.

This account is bounded to [March 2022 security incident](https://mailchimp.com/newsroom/march-2022-security-incident/). 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/mailchimp-security-incident-2022/stix.json>)

## Sources

Primary source records used to research this incident.

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

### March 2022 security incident

official · Mailchimp

<https://mailchimp.com/newsroom/march-2022-security-incident/>

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

Review the supporting structured claims.

1. **Resulted In · 83% confidence · current**  
   Mailchimp security incident: Social engineering of internal support tool (0ktapus-adjacent).
2. **Resulted In · 88% confidence · current**  
   Mailchimp security incident: Used to target crypto customers' mailing lists.
3. **Resulted In · 100% confidence · current**  
   Mailchimp security incident: The reviewed source documents the mailchimp security incident involving Mailchimp.
4. **Affected Organization · 100% confidence · current**  
   Mailchimp security incident: Mailchimp

</details>