> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/suspicious-dmarc-result.md).
# Suspicious DMARC result
### Synopsis
| Field | Value |
| -------------------- | ------------------------ |
| Activation Period | 14 Days |
| Training Period | 30 Days |
| Test Period | N/A (single event) |
| Deduplication Period | 1 Day |
| Required Data | Microsoft 365 Emails |
| Detection Modules | Email |
| Detector Tags | Spoofing |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
### Description
The email has a suspicious DMARC result of either fail or none, which may indicate a potential domain misconfiguration or spoofing.
### Attacker's Goals
Impersonate internal users or familiar individuals.
* Trick users into clicking on malicious links or attachments.
### Investigative actions
* Check the email address for any unusual spellings.
* Check the email address for any missing letters.
* Check the reason DMARC didn't pass and the action.
* Check if the email was delivered to the recipients based on the action taken, even though DMARC did not pass.
* Verify whether the sender's IP address has appeared in different log sources before and its reputation.
* If the message contains attachments or links, scrutinize them for any suspicious indications.
* Monitor further actions taken, such as file downloads or access to potentially malicious links.
### Variations
DMARC deviation from historically compliant domain
**Synopsis**
| Field | Value |
| ----------------- | ------------------------ |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
**Description**
An email was sent from a domain that has historically passed DMARC checks but returned a suspicious DMARC result of either fail or none for the first time in the past 30 days.
* This deviation may indicate an attempt to spoof or impersonate a legitimate external sender.
* Such sudden DMARC outcome from a previously trusted external domain warrants further investigation.
**Attacker's Goals**
Impersonate internal users or familiar individuals.
* Trick users into clicking on malicious links or attachments.
**Investigative actions**
* Check the email address for any unusual spellings.
* Check the email address for any missing letters.
* Check the reason DMARC didn't pass and the action.
* Check if the email was delivered to the recipients based on the action taken, even though DMARC did not pass.
* Verify whether the sender's IP address has appeared in different log sources before and its reputation.
* If the message contains attachments or links, scrutinize them for any suspicious indications.
* Monitor further actions taken, such as file downloads or access to potentially malicious links.
DMARC failure bypassed domain policy
**Synopsis**
| Field | Value |
| ----------------- | ------------------------ |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
**Description**
An email with a DMARC result of fail was delivered to a user's Inbox, despite the sender domain having a DMARC policy of reject.
* This indicates the message should have been rejected according to the domain owner policy, but was instead accepted and delivered, potentially exposing the user to email spoofing or phishing.
* This suggests a potential policy bypass or misconfiguration in mail filtering.
**Attacker's Goals**
Impersonate internal users or familiar individuals.
* Trick users into clicking on malicious links or attachments.
**Investigative actions**
* Check the email address for any unusual spellings.
* Check the email address for any missing letters.
* Check the reason DMARC didn't pass and the action.
* Check if the email was delivered to the recipients based on the action taken, even though DMARC did not pass.
* Verify whether the sender's IP address has appeared in different log sources before and its reputation.
* If the message contains attachments or links, scrutinize them for any suspicious indications.
* Monitor further actions taken, such as file downloads or access to potentially malicious links.
DMARC failed with non-enforcing policy
**Synopsis**
| Field | Value |
| ----------------- | ------------------------ |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
**Description**
An email was received with DMARC=fail and policy=none, meaning the message failed both SPF and DKIM identifier alignment checks, but no enforcement action (quarantine or reject) was requested by the sending domain.
* This may indicate an overly permissive DMARC configuration on the sender side and could allow unauthenticated messages to reach users' inboxes.
* Such configurations are often exploited in phishing or spoofing campaigns, and should be treated with caution.
**Attacker's Goals**
Impersonate internal users or familiar individuals.
* Trick users into clicking on malicious links or attachments.
**Investigative actions**
* Check the email address for any unusual spellings.
* Check the email address for any missing letters.
* Check the reason DMARC didn't pass and the action.
* Check if the email was delivered to the recipients based on the action taken, even though DMARC did not pass.
* Verify whether the sender's IP address has appeared in different log sources before and its reputation.
* If the message contains attachments or links, scrutinize them for any suspicious indications.
* Monitor further actions taken, such as file downloads or access to potentially malicious links.
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/suspicious-dmarc-result.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.