Microsoft Sentinel Analytic Rules
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A host is potentially running PowerShell to send HTTPS requests ASIM Web Session schema

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Id42436753-9944-4d70-801c-daaa4d19ddd2
RulenameA host is potentially running PowerShell to send HTTP(S) requests (ASIM Web Session schema)
DescriptionThis 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.<br><br>

This analytic rule uses ASIM and supports any built-in or custom source that supports the ASIM WebSession schema (ASIM WebSession Schema)
SeverityMedium
TacticsCommandandControl
DefenseEvasion
Required data connectorsSquidProxy
Zscaler
KindScheduled
Query frequency15m
Query period15m
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimWebSession/UnusualUAPowershell.yaml
Version1.1.3
Arm template42436753-9944-4d70-801c-daaa4d19ddd2.json
Deploy To Azure
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])
customDetails:
  UserAgent: HttpUserAgent
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 PoerShell and indicates suspicious activity on the host.
eventGroupingSettings:
  aggregationKind: AlertPerResult
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
metadata:
  support:
    tier: Community
  categories:
    domains:
    - Security - Threat Protection
  author:
    name: Yaron
  source:
    kind: Community
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimWebSession/UnusualUAPowershell.yaml
requiredDataConnectors:
- dataTypes:
  - SquidProxy_CL
  connectorId: SquidProxy
- dataTypes:
  - CommonSecurityLog
  connectorId: Zscaler
queryPeriod: 15m
tactics:
- CommandandControl
- DefenseEvasion
severity: Medium
triggerOperator: gt
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)'  
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)
version: 1.1.3
kind: Scheduled
id: 42436753-9944-4d70-801c-daaa4d19ddd2
queryFrequency: 15m
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
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-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 PoerShell 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",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandandControl",
          "DefenseEvasion"
        ],
        "tags": [
          {
            "ParentAlert": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaPowershellUserAgentDetected.yaml",
            "version": "1.0.0"
          },
          {
            "Schema": "ASimWebSession",
            "SchemaVersion": "0.2.1"
          }
        ],
        "templateVersion": "1.1.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}