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https://github.com/splunk/security_content
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Michael Haag
88 lines
4.4 KiB
YAML
88 lines
4.4 KiB
YAML
name: Exchange PowerShell Module Usage
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id: 2d10095e-05ae-11ec-8fdf-acde48001122
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version: 13
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date: '2025-07-29'
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author: Michael Haag, Splunk
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status: production
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type: TTP
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description:
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The following analytic detects the usage of specific Exchange PowerShell
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modules, such as New-MailboxExportRequest, New-ManagementRoleAssignment, New-MailboxSearch,
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and Get-Recipient. It leverages PowerShell Script Block Logging (EventCode 4104)
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to identify these commands. This activity is significant because these modules can
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be exploited by adversaries who have gained access via ProxyShell or ProxyNotShell
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vulnerabilities. If confirmed malicious, attackers could export mailbox contents,
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assign management roles, conduct mailbox searches, or view recipient objects, potentially
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leading to data exfiltration, privilege escalation, or unauthorized access to sensitive
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information.
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data_source:
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- Powershell Script Block Logging 4104
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search:
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'`powershell` EventCode=4104 ScriptBlockText IN ("*New-MailboxExportRequest*",
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"*New-ManagementRoleAssignment*", "*New-MailboxSearch*", "*Get-Recipient*", "Search-Mailbox")
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signature signature_id user_id vendor_product EventID Guid Opcode Name Path ProcessID
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ScriptBlockId ScriptBlockText | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `exchange_powershell_module_usage_filter`'
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how_to_implement:
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To successfully implement this analytic, you will need to enable
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PowerShell Script Block Logging on some or all endpoints. Additional setup here
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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.
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known_false_positives:
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Administrators or power users may use this PowerShell commandlet
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for troubleshooting.
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references:
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- https://docs.microsoft.com/en-us/powershell/module/exchange/new-mailboxexportrequest?view=exchange-ps
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- https://docs.microsoft.com/en-us/powershell/module/exchange/new-managementroleassignment?view=exchange-ps
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- https://blog.orange.tw/2021/08/proxyshell-a-new-attack-surface-on-ms-exchange-part-3.html
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- https://www.zerodayinitiative.com/blog/2021/8/17/from-pwn2own-2021-a-new-attack-surface-on-microsoft-exchange-proxyshell
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- https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
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- https://www.cisa.gov/uscert/ncas/alerts/aa22-264a
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- https://learn.microsoft.com/en-us/powershell/module/exchange/new-mailboxsearch?view=exchange-ps
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- https://learn.microsoft.com/en-us/powershell/module/exchange/get-recipient?view=exchange-ps
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- https://thedfirreport.com/2022/03/21/apt35-automates-initial-access-using-proxyshell/
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drilldown_searches:
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- name: View the detection results for - "$dest$"
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search: '%original_detection_search% | search dest = "$dest$"'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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- name: View risk events for the last 7 days for - "$dest$"
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search:
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'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$")
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starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime
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values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories)
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as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic)
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as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)`'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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rba:
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message: Suspicious Exchange PowerShell module usaged was identified on $dest$.
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risk_objects:
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- field: dest
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type: system
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score: 32
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threat_objects: []
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tags:
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analytic_story:
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- ProxyNotShell
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- CISA AA22-277A
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- ProxyShell
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- BlackByte Ransomware
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- CISA AA22-264A
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- Scattered Spider
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asset_type: Endpoint
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mitre_attack_id:
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- T1059.001
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/exchange/windows-powershell.log
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source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
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sourcetype: XmlWinEventLog
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