MediumSplunk security content Michael Haag +1

Exchange PowerShell Module Usage

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.

Detection logic

Detection requirements

Platform: Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
Log source category: powershell_script_block_logging_4104

Known benign triggers

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

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
blog.orange.tw/2021/08/proxyshell-a-new-attack-surface-on-ms-exchange-part-3.html	Unclassified	Only this detection cites it
docs.microsoft.com/en-us/powershell/module/exchange/new-mailboxexportrequest?view=exchange-ps	Product documentation	3from 2 sources
docs.microsoft.com/en-us/powershell/module/exchange/new-managementroleassignment?view=exchange-ps	Product documentation	2from 2 sources
learn.microsoft.com/en-us/powershell/module/exchange/get-recipient?view=exchange-ps	Product documentation	Only this detection cites it
learn.microsoft.com/en-us/powershell/module/exchange/new-mailboxsearch?view=exchange-ps	Product documentation	Only this detection cites it
thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/	Threat report	3from 2 sources
thedfirreport.com/2022/03/21/apt35-automates-initial-access-using-proxyshell/	Threat report	4from 2 sources
www.cisa.gov/uscert/ncas/alerts/aa22-264a	Vendor advisory	Only this detection cites it
www.zerodayinitiative.com/blog/2021/8/17/from-pwn2own-2021-a-new-attack-surface-on-microsoft-exchange-proxyshell	Unclassified	2

Detection rules

Exchange PowerShell Module Usage

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules