name: Exchange PowerShell Module Usage
id: 2d10095e-05ae-11ec-8fdf-acde48001122
version: 1
date: '2021-08-27'
author: Michael Haag
type: TTP
datamodel: []
description: 'The following analytic identifies the usage of Exchange PowerShell modules
  that were recently used for a proof of concept related to ProxyShell. Currently,
  there is no active data shared or data we could re-produce relate to this part of
  the ProxyShell chain of exploits.  \

  Inherently, the usage of the modules is not malicious, but reviewing parallel processes,
  and user, of the session will assist with determining the intent. \

  Module - New-MailboxExportRequest will begin the process of exporting contents of
  a primary mailbox or archive to a .pst file. \

  Module - New-managementroleassignment can assign a management role to a management
  role group, management role assignment policy, user, or universal security group
  (USG).'
search: '`powershell` EventCode=4104 Message IN ("*New-MailboxExportRequest*", "*New-ManagementRoleAssignment*")
  | stats count min(_time) as firstTime max(_time) as lastTime by Path Message OpCode
  ComputerName User EventCode| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
  | `exchange_powershell_module_usage_filter`'
how_to_implement: To successfully implement this analytic, you will need to enable
  PowerShell Script Block Logging on some or all endpoints. Additional setup here
  https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.
known_false_positives: Administrators or power users may use this PowerShell commandlet
  for troubleshooting.
references:
- https://docs.microsoft.com/en-us/powershell/module/exchange/new-mailboxexportrequest?view=exchange-ps
- https://docs.microsoft.com/en-us/powershell/module/exchange/new-managementroleassignment?view=exchange-ps
- https://blog.orange.tw/2021/08/proxyshell-a-new-attack-surface-on-ms-exchange-part-3.html
- https://www.zerodayinitiative.com/blog/2021/8/17/from-pwn2own-2021-a-new-attack-surface-on-microsoft-exchange-proxyshell
- https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
tags:
  analytic_story:
  - ProxyShell
  confidence: 50
  context:
  - Source:Endpoint
  - Stage:Discovery
  - Stage:Recon
  dataset: []
  impact: 30
  kill_chain_phases:
  - Reconnaissance
  - Exploitation
  message: Local user discovery enumeration using PowerShell on $dest$ by $user$
  mitre_attack_id:
  - T1059
  - T1059.001
  observable:
  - name: dest
    type: Endpoint
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Path
  - Message
  - OpCode
  - ComputerName
  - User
  - EventCode
  risk_score: 15
  security_domain: endpoint