> 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/exchange-user-mailbox-forwarding.md).
# Exchange user mailbox forwarding
### Synopsis
| Field | Value |
| -------------------- | ------------------------------------------------------------------------------------------------------------- |
| Activation Period | 14 Days |
| Training Period | 30 Days |
| Test Period | N/A (single event) |
| Deduplication Period | 1 Day |
| Required Data | Office 365 Audit |
| Detection Modules | Identity Threat Module, SaaS Threat Detection, Email |
| ATT\&CK Tactic | Collection (TA0009), Exfiltration (TA0010) |
| ATT\&CK Technique | Email Collection: Email Forwarding Rule (T1114.003), Automated Exfiltration (T1020), Email Collection (T1114) |
| Severity | Low |
### Description
A user configured Exchange SMTP forwarding on a mailbox, which forwards all emails sent to that mailbox to a specified recipient.
### Attacker's Goals
Leverage a compromised user account to modify a mailbox's settings to forward emails to an external recipient and collect sensitive information.
### Investigative actions
* Look for signs that the user account and mailbox are compromised (e.g. abnormal logins, unusual activity).
* Check if the forwarding domain is an unknown external domain.
* Investigate the IP address associated with the rule.
* Follow further actions done by the account.
### Variations
Exchange user mailbox forwarding by a delegate user
**Synopsis**
| Field | Value |
| ----------------- | ------------------------------------------------------------------------------------------------------------- |
| ATT\&CK Tactic | Collection (TA0009), Exfiltration (TA0010) |
| ATT\&CK Technique | Email Collection: Email Forwarding Rule (T1114.003), Automated Exfiltration (T1020), Email Collection (T1114) |
| Severity | Informational |
**Description**
A user configured Exchange SMTP forwarding on a mailbox, which forwards all emails sent to that mailbox to a specified recipient. The user who set the forwarding is a delegated user, who performed this action on behalf of another user.
**Attacker's Goals**
Leverage a compromised user account to modify a mailbox's settings to forward emails to an external recipient and collect sensitive information.
**Investigative actions**
* Look for signs that the user account and mailbox are compromised (e.g. abnormal logins, unusual activity).
* Check if the forwarding domain is an unknown external domain.
* Investigate the IP address associated with the rule.
* Follow further actions done by the account.
Suspicious Exchange user mailbox forwarding
**Synopsis**
| Field | Value |
| ----------------- | ------------------------------------------------------------------------------------------------------------- |
| ATT\&CK Tactic | Collection (TA0009), Exfiltration (TA0010) |
| ATT\&CK Technique | Email Collection: Email Forwarding Rule (T1114.003), Automated Exfiltration (T1020), Email Collection (T1114) |
| Severity | Medium |
**Description**
A user configured Exchange SMTP forwarding on a mailbox, which forwards all emails sent to that mailbox to a specified recipient.
**Attacker's Goals**
Leverage a compromised user account to modify a mailbox's settings to forward emails to an external recipient and collect sensitive information.
**Investigative actions**
* Look for signs that the user account and mailbox are compromised (e.g. abnormal logins, unusual activity).
* Check if the forwarding domain is an unknown external domain.
* Investigate the IP address associated with the rule.
* Follow further actions done by the account.
---
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