> 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-dkim-result.md).
# Suspicious DKIM 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 contains a suspicious DKIM entry, showing either an unexpected verification result (none, fail, or policy) or a mismatched signing domain, which may indicate potential tampering or spoofing activity.
### Attacker's Goals
Impersonate internal users or familiar individuals and trick them into clicking on malicious links or attachments.
### Investigative actions
* Check the email address for any unusual spellings, missing letters, or unknown domains.
* Examine the sender's IP address and reputation, and check why DKIM didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
* 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
Known domain DKIM deviation
**Synopsis**
| Field | Value |
| ----------------- | ------------------------ |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
**Description**
* An email was sent from a commonly seen domain in the organization, that has historically passed DKIM checks, but returned a suspicious DKIM result of fail
* This deviation may indicate an attempt to spoof or impersonate a legitimate external sender.
* Such sudden DKIM outcome from a previously trusted external domain warrants further investigation.
**Attacker's Goals**
Impersonate internal users or familiar individuals and trick them into clicking on malicious links or attachments.
**Investigative actions**
* Check the email address for any unusual spellings, missing letters, or unknown domains.
* Examine the sender's IP address and reputation, and check why DKIM didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
* 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.
Lack DKIM signature from typically signing domains
**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 DKIM checks, but returned a suspicious DKIM result of none
* A none DKIM result implies on an unsigned email, which is atypical for domains with previous signed messages.
* This deviation may indicate an attempt to spoof or impersonate a legitimate external sender.
* Such sudden DKIM outcome from a previously trusted external domain warrants further investigation.
**Attacker's Goals**
Impersonate internal users or familiar individuals and trick them into clicking on malicious links or attachments.
**Investigative actions**
* Check the email address for any unusual spellings, missing letters, or unknown domains.
* Examine the sender's IP address and reputation, and check why DKIM didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
* 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.
DKIM results lacking sender correlation
**Synopsis**
| Field | Value |
| ----------------- | ------------------------ |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
**Description**
* The email's authentication results have no indication of proper signing from the email's sender
* This deviation may indicate an attempt to spoof or impersonate a legitimate external sender.
**Attacker's Goals**
Impersonate internal users or familiar individuals and trick them into clicking on malicious links or attachments.
**Investigative actions**
* Check the email address for any unusual spellings, missing letters, or unknown domains.
* Examine the sender's IP address and reputation, and check why DKIM didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
* 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 suspicious DKIM result
**Synopsis**
| Field | Value |
| ----------------- | ------------------------ |
| ATT\&CK Tactic | Defense Evasion (TA0005) |
| ATT\&CK Technique | Impersonation (T1656) |
| Severity | Informational |
**Description**
* An email was sent from a commonly seen domain that had no other suspicious DKIM outcomes for the past 30 days.
* This may indicate an attempt to spoof or impersonate a legitimate external sender.
**Attacker's Goals**
Impersonate internal users or familiar individuals and trick them into clicking on malicious links or attachments.
**Investigative actions**
* Check the email address for any unusual spellings, missing letters, or unknown domains.
* Examine the sender's IP address and reputation, and check why DKIM didn't pass.
* Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
* 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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