> 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-spf-result.md).
# Suspicious SPF 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 SPF result of fail, soft fail, or policy, 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.
* Verify the sender's domain to confirm its legitimacy.
* Examine the sender's IP address and reputation.
* Verify the domain's connection to the IP address and investigate the reason SPF didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before.
* Verify if the sender's IP address is identifiable.
* 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
Internal domain SPF deviation
**Synopsis**
| Field | Value |
| ----------------- | ------------------------ |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
**Description**
* An email was sent from an internal root domain that has historically passed SPF checks, but returned a suspicious SPF result of fail, soft fail, or policy for the first time in the past 30 days.
* This deviation may indicate an attempt to spoof or impersonate a trusted internal sender, a tactic commonly associated with BEC and internal phishing.
* Such a sudden SPF outcome from a typically trusted 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.
* Verify the sender's domain to confirm its legitimacy.
* Examine the sender's IP address and reputation.
* Verify the domain's connection to the IP address and investigate the reason SPF didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before.
* Verify if the sender's IP address is identifiable.
* 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.
Known domain SPF deviation
**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 SPF checks, but returned a suspicious SPF result of fail, soft fail, or policy for the first time in the past 30 days.
* This deviation may indicate an attempt to spoof or impersonate a legitimate external sender.
* Such a sudden SPF 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.
* Verify the sender's domain to confirm its legitimacy.
* Examine the sender's IP address and reputation.
* Verify the domain's connection to the IP address and investigate the reason SPF didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before.
* Verify if the sender's IP address is identifiable.
* 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.
---
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