A host is potentially running PowerShell to send HTTPS requests ASIM Web Session schema

let threatCategory="Powershell";
let knownUserAgentsIndicators = materialize(externaldata(UserAgent:string, Category:string)
    [ @"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/UnusualUserAgents.csv"]
        with(format="csv", ignoreFirstRecord=True));
let knownUserAgents=toscalar(knownUserAgentsIndicators | where Category==threatCategory | where isnotempty(UserAgent) | summarize make_list(UserAgent));
let customUserAgents=toscalar(_GetWatchlist("UnusualUserAgents") | where SearchKey==threatCategory | extend UserAgent=column_ifexists("UserAgent","") | where isnotempty(UserAgent) | summarize make_list(UserAgent));
let fullUAList = array_concat(knownUserAgents,customUserAgents);
_Im_WebSession(httpuseragent_has_any=fullUAList)
| project SrcIpAddr, Url, TimeGenerated, HttpUserAgent, SrcUsername
| extend AccountName = tostring(split(SrcUsername, "@")[0]), AccountUPNSuffix = tostring(split(SrcUsername, "@")[1])

queryPeriod: 15m
kind: Scheduled
entityMappings:
- entityType: URL
  fieldMappings:
  - identifier: Url
    columnName: Url
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
- entityType: Account
  fieldMappings:
  - identifier: FullName
    columnName: SrcUsername
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
requiredDataConnectors:
- connectorId: SquidProxy
  dataTypes:
  - SquidProxy_CL
- connectorId: Zscaler
  dataTypes:
  - CommonSecurityLog
description: |
  'This rule identifies a web request with a user agent header known to belong PowerShell. <br>You can add custom Powershell indicating User-Agent headers using a watchlist, for more information refer to the [UnusualUserAgents Watchlist](https://aka.ms/ASimUnusualUserAgentsWatchlist).<br><br>
   This analytic rule uses [ASIM](https://aka.ms/AboutASIM) and supports any built-in or custom source that supports the ASIM WebSession schema (ASIM WebSession Schema)'  
queryFrequency: 15m
triggerOperator: gt
eventGroupingSettings:
  aggregationKind: AlertPerResult
metadata:
  source:
    kind: Community
  author:
    name: Yaron
  categories:
    domains:
    - Security - Threat Protection
  support:
    tier: Community
query: |
  let threatCategory="Powershell";
  let knownUserAgentsIndicators = materialize(externaldata(UserAgent:string, Category:string)
      [ @"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/UnusualUserAgents.csv"]
          with(format="csv", ignoreFirstRecord=True));
  let knownUserAgents=toscalar(knownUserAgentsIndicators | where Category==threatCategory | where isnotempty(UserAgent) | summarize make_list(UserAgent));
  let customUserAgents=toscalar(_GetWatchlist("UnusualUserAgents") | where SearchKey==threatCategory | extend UserAgent=column_ifexists("UserAgent","") | where isnotempty(UserAgent) | summarize make_list(UserAgent));
  let fullUAList = array_concat(knownUserAgents,customUserAgents);
  _Im_WebSession(httpuseragent_has_any=fullUAList)
  | project SrcIpAddr, Url, TimeGenerated, HttpUserAgent, SrcUsername
  | extend AccountName = tostring(split(SrcUsername, "@")[0]), AccountUPNSuffix = tostring(split(SrcUsername, "@")[1])  
name: A host is potentially running PowerShell to send HTTP(S) requests (ASIM Web Session schema)
id: 42436753-9944-4d70-801c-daaa4d19ddd2
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimWebSession/UnusualUAPowershell.yaml
severity: Medium
version: 1.1.5
relevantTechniques:
- T1132
- T1140
- T1059.001
alertDetailsOverride:
  alertDisplayNameFormat: Host {{SrcIpAddr}} is potentially running PowerShell
  alertDescriptionFormat: The host at address {{SrcIpAddr}} sent an HTTP request to the URL {{Url}} with the HTTP user agent header {{HttpUserAgent}}. This user agent is known to be used by PowerShell and indicates suspicious activity on the host.
tags:
- ParentAlert: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaPowershellUserAgentDetected.yaml
  version: 1.0.0
- Schema: ASimWebSession
  SchemaVersion: 0.2.1
triggerThreshold: 0
customDetails:
  UserAgent: HttpUserAgent
tactics:
- CommandAndControl
- DefenseEvasion
- Execution