GitHub Repo

Detection: Exchange PowerShell Module Usage

Updated Date: 2026-05-13 ID: 2d10095e-05ae-11ec-8fdf-acde48001122 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the usage of specific Exchange PowerShell modules, such as New-MailboxExportRequest, New-ManagementRoleAssignment, New-MailboxSearch, and Get-Recipient. It leverages PowerShell Script Block Logging (EventCode 4104) to identify these commands. This activity is significant because these modules can be exploited by adversaries who have gained access via ProxyShell or ProxyNotShell vulnerabilities. If confirmed malicious, attackers could export mailbox contents, assign management roles, conduct mailbox searches, or view recipient objects, potentially leading to data exfiltration, privilege escalation, or unauthorized access to sensitive information.

 1`powershell` EventCode=4104 ScriptBlockText IN ("*New-MailboxExportRequest*", "*New-ManagementRoleAssignment*", "*New-MailboxSearch*", "*Get-Recipient*", "Search-Mailbox")
 2  
 3| fillnull
 4  
 5| stats count min(_time) as firstTime max(_time) as lastTime
 6    BY dest signature signature_id
 7       user_id vendor_product EventID
 8       Guid Opcode Name
 9       Path ProcessID ScriptBlockId
10       ScriptBlockText
11  
12| `security_content_ctime(firstTime)`
13  
14| `security_content_ctime(lastTime)`
15  
16| `exchange_powershell_module_usage_filter`

Data Source

Name Platform Sourcetype Source
Powershell Script Block Logging 4104 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-PowerShell/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
exchange_powershell_module_usage_filter search *
exchange_powershell_module_usage_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
ID Technique Tactic
T1059.001 PowerShell Execution
Installation
DE.CM
CIS 10

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 Finding (Notable) Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Intermediate Finding (Risk Event) No
TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.

Implementation

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba.

Known False Positives

Administrators or power users may use this PowerShell commandlet for troubleshooting.

Associated Analytic Story

Finding

Title Entity Field Entity Type Risk Score
Suspicious Exchange PowerShell module usaged was identified on $dest$. dest system 50

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-PowerShell/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-PowerShell/Operational XmlWinEventLog

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: 17