mirror of
https://github.com/splunk/security_content
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Bhavin Patel
90 lines
4.0 KiB
YAML
90 lines
4.0 KiB
YAML
name: Exchange PowerShell Module Usage
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id: 2d10095e-05ae-11ec-8fdf-acde48001122
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version: 5
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date: '2023-07-10'
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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: 'The following analytic identifies the usage of Exchange PowerShell modules
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that were recently used for a proof of concept related to ProxyShell. Adversaries
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may abuse a limited set of PwSh Modules related to Exchange once gained access via
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ProxyShell or ProxyNotShell.\
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Inherently, the usage of the modules is not malicious, but reviewing parallel processes,
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and user, of the session will assist with determining the intent. \
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Module - New-MailboxExportRequest will begin the process of exporting contents of
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a primary mailbox or archive to a .pst file. \
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Module - New-managementroleassignment can assign a management role to a management
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role group, management role assignment policy, user, or universal security group
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(USG). \
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Module - New-MailboxSearch cmdlet to create a mailbox search and either get an estimate
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of search results, place search results on In-Place Hold or copy them to a Discovery
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mailbox. You can also place all contents in a mailbox on hold by not specifying
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a search query, which accomplishes similar results as Litigation Hold. \ Module
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- Get-Recipient cmdlet to view existing recipient objects in your organization.
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This cmdlet returns all mail-enabled objects (for example, mailboxes, mail users,
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mail contacts, and distribution groups).'
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data_source:
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- Powershell 4104
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search: '`powershell` EventCode=4104 ScriptBlockText IN ("*New-MailboxExportRequest*",
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"*New-ManagementRoleAssignment*", "*New-MailboxSearch*", "*Get-Recipient*", "Search-Mailbox")
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| stats count min(_time) as firstTime max(_time) as lastTime by Opcode Computer
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UserID EventCode ScriptBlockText | rename Computer as dest |rename UserID as user | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `exchange_powershell_module_usage_filter`'
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how_to_implement: 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://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.
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known_false_positives: 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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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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asset_type: Endpoint
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confidence: 80
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impact: 40
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message: Suspicious Exchange PowerShell module usaged was identified on $dest$.
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mitre_attack_id:
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- T1059
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- T1059.001
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observable:
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- name: dest
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type: Endpoint
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role:
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- Victim
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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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required_fields:
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- _time
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- ScriptBlockText
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- Opcode
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- Computer
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- UserID
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- EventCode
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risk_score: 32
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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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