Zscaler - Unexpected event count of rejects by policy

let threshold = 1000;
ZPAEvent
| where EventResult has "REJECTED_BY_POLICY"
| summarize rejected = count() by EventResult, DstUserName
| where rejected > threshold
| extend AccountCustomEntity = DstUserName

entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: Name
    columnName: AccountCustomEntity
name: Zscaler - Unexpected event count of rejects by policy
kind: Scheduled
triggerOperator: gt
status: Available
queryPeriod: 1h
requiredDataConnectors:
- connectorId: CustomLogsAma
  datatypes:
  - ZPA_CL
tactics:
- InitialAccess
query: |
  let threshold = 1000;
  ZPAEvent
  | where EventResult has "REJECTED_BY_POLICY"
  | summarize rejected = count() by EventResult, DstUserName
  | where rejected > threshold
  | extend AccountCustomEntity = DstUserName
description: |
  'Detects unexpected event count of rejects by policy.'
severity: High
id: 593e3e2a-43ce-11ec-81d3-0242ac130003
triggerThreshold: 0
queryFrequency: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Zscaler%20Private%20Access%20%28ZPA%29/Analytic%20Rules/ZscalerUnexpectedCountEventResult.yaml
version: 1.0.2
relevantTechniques:
- T1078
- T1133

{
  "$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/593e3e2a-43ce-11ec-81d3-0242ac130003')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/593e3e2a-43ce-11ec-81d3-0242ac130003')]",
      "properties": {
        "alertRuleTemplateName": "593e3e2a-43ce-11ec-81d3-0242ac130003",
        "customDetails": null,
        "description": "'Detects unexpected event count of rejects by policy.'\n",
        "displayName": "Zscaler - Unexpected event count of rejects by policy",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "Name"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Zscaler%20Private%20Access%20%28ZPA%29/Analytic%20Rules/ZscalerUnexpectedCountEventResult.yaml",
        "query": "let threshold = 1000;\nZPAEvent\n| where EventResult has \"REJECTED_BY_POLICY\"\n| summarize rejected = count() by EventResult, DstUserName\n| where rejected > threshold\n| extend AccountCustomEntity = DstUserName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1078",
          "T1133"
        ],
        "templateVersion": "1.0.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}