| ID | Technique | Tactic |
|---|---|---|
| T1114.003 | Email Forwarding Rule | Collection |
| T1114 | Email Collection | Collection |
Detection: O365 Suspicious Admin Email Forwarding
DEPRECATED DETECTION
This detection has been marked as deprecated by the Splunk Threat Research team. This means that it will no longer be maintained or supported. If you have any questions or concerns, please reach out to us at research@splunk.com.
Description
DEPRECATION NOTE - This search has been deprecated and replaced with O365 Mailbox Email Forwarding Enabled. This search detects when an admin configured a forwarding rule for multiple mailboxes to the same destination.
Search
1`o365_management_activity` Operation=Set-Mailbox
2| spath input=Parameters
3| rename Identity AS src_user
4| search ForwardingAddress=*
5| stats dc(src_user) AS count_src_user earliest(_time) as firstTime latest(_time) as lastTime values(src_user) AS src_user values(user) AS user by ForwardingAddress
6| where count_src_user > 1
7|`security_content_ctime(firstTime)`
8|`security_content_ctime(lastTime)`
9|`o365_suspicious_admin_email_forwarding_filter`
Data Source
No data sources specified for this detection.
Macros Used
| Name | Value |
|---|---|
| o365_management_activity | sourcetype=o365:management:activity |
| o365_suspicious_admin_email_forwarding_filter | search * |
o365_suspicious_admin_email_forwarding_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
MITRE ATT&CK
Kill Chain Phases
NIST
CIS
Threat Actors
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
Kimsuky
LAPSUS$
Silent Librarian
Star Blizzard
Ember Bear
Magic Hound
Scattered Spider
Silent Librarian
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
| Setting | Value |
|---|---|
| Disabled | true |
| Cron Schedule | 0 * * * * |
| Earliest Time | -70m@m |
| Latest Time | -10m@m |
| Schedule Window | auto |
| Creates Risk Event | True |
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.
Implementation
You must install splunk Microsoft Office 365 add-on. This search works with o365:management:activity
Known False Positives
unknown
Associated Analytic Story
Risk Based Analytics (RBA)
| Risk Message | Risk Score | Impact | Confidence |
|---|---|---|---|
| User $user$ has configured a forwarding rule for multiple mailboxes to the same destination $ForwardingAddress$ | 48 | 80 | 60 |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Detection Testing
| Test Type | Status | Dataset | Source | Sourcetype |
|---|---|---|---|---|
| Validation | Not Applicable | N/A | N/A | N/A |
| Unit | ✅ Passing | Dataset | o365 |
o365:management:activity |
| Integration | ✅ Passing | Dataset | o365 |
o365:management:activity |
Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 2