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])

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.
entityMappings:
- fieldMappings:
  - identifier: Url
    columnName: Url
  entityType: URL
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
  entityType: IP
- fieldMappings:
  - identifier: FullName
    columnName: SrcUsername
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  entityType: Account
metadata:
  categories:
    domains:
    - Security - Threat Protection
  support:
    tier: Community
  source:
    kind: Community
  author:
    name: Yaron
id: 42436753-9944-4d70-801c-daaa4d19ddd2
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimWebSession/UnusualUAPowershell.yaml
tactics:
- CommandAndControl
- DefenseEvasion
- Execution
kind: Scheduled
requiredDataConnectors:
- dataTypes:
  - SquidProxy_CL
  connectorId: SquidProxy
- dataTypes:
  - CommonSecurityLog
  connectorId: Zscaler
queryPeriod: 15m
eventGroupingSettings:
  aggregationKind: AlertPerResult
severity: Medium
relevantTechniques:
- T1132
- T1140
- T1059.001
triggerThreshold: 0
version: 1.1.5
customDetails:
  UserAgent: HttpUserAgent
name: A host is potentially running PowerShell to send HTTP(S) requests (ASIM Web Session schema)
triggerOperator: gt
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])
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
tags:
- ParentAlert: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaPowershellUserAgentDetected.yaml
  version: 1.0.0
- SchemaVersion: 0.2.1
  Schema: ASimWebSession

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/42436753-9944-4d70-801c-daaa4d19ddd2')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/42436753-9944-4d70-801c-daaa4d19ddd2')]",
      "properties": {
        "alertDetailsOverride": {
          "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.",
          "alertDisplayNameFormat": "Host {{SrcIpAddr}} is potentially running PowerShell"
        },
        "alertRuleTemplateName": "42436753-9944-4d70-801c-daaa4d19ddd2",
        "customDetails": {
          "UserAgent": "HttpUserAgent"
        },
        "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>\n 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)'\n",
        "displayName": "A host is potentially running PowerShell to send HTTP(S) requests (ASIM Web Session schema)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "URL",
            "fieldMappings": [
              {
                "columnName": "Url",
                "identifier": "Url"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "SrcUsername",
                "identifier": "FullName"
              },
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimWebSession/UnusualUAPowershell.yaml",
        "query": "let threatCategory=\"Powershell\";\nlet knownUserAgentsIndicators = materialize(externaldata(UserAgent:string, Category:string)\n    [ @\"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/UnusualUserAgents.csv\"]\n        with(format=\"csv\", ignoreFirstRecord=True));\nlet knownUserAgents=toscalar(knownUserAgentsIndicators | where Category==threatCategory | where isnotempty(UserAgent) | summarize make_list(UserAgent));\nlet customUserAgents=toscalar(_GetWatchlist(\"UnusualUserAgents\") | where SearchKey==threatCategory | extend UserAgent=column_ifexists(\"UserAgent\",\"\") | where isnotempty(UserAgent) | summarize make_list(UserAgent));\nlet fullUAList = array_concat(knownUserAgents,customUserAgents);\n_Im_WebSession(httpuseragent_has_any=fullUAList)\n| project SrcIpAddr, Url, TimeGenerated, HttpUserAgent, SrcUsername\n| extend AccountName = tostring(split(SrcUsername, \"@\")[0]), AccountUPNSuffix = tostring(split(SrcUsername, \"@\")[1])\n",
        "queryFrequency": "PT15M",
        "queryPeriod": "PT15M",
        "severity": "Medium",
        "subTechniques": [
          "T1059.001"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl",
          "DefenseEvasion",
          "Execution"
        ],
        "tags": [
          {
            "ParentAlert": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaPowershellUserAgentDetected.yaml",
            "version": "1.0.0"
          },
          {
            "Schema": "ASimWebSession",
            "SchemaVersion": "0.2.1"
          }
        ],
        "techniques": [
          "T1059",
          "T1132",
          "T1140"
        ],
        "templateVersion": "1.1.5",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}