PasswordSpray.json

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    },
    "analytic-id": {
      "type": "string",
      "defaultValue": "227bc6a9-c410-4862-ac5a-dd3e2ff14a6f",
      "minLength": 1,
      "metadata": {
        "description": "Unique id for the scheduled alert rule"
      }
    }
  },
  "resources": [
    {
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/',parameters('analytic-id'))]",
      "apiVersion": "2020-01-01",
      "kind": "Scheduled",
      "location": "[resourceGroup().location]",
      "properties": {
        "description": "This query searches for failed attempts to log into the Okta console from more than 15 various users within a 5 minute timeframe from the same source. This is a potential indication of a password spray attack",
        "displayName": "Potential Password Spray Attack",
        "enabled": false,
        "query": "\nlet FailureThreshold = 15;\nlet FailedEvents = Okta_CL\n| where eventType_s =~ \"user.session.start\"and outcome_reason_s in (\"VERIFICATION_ERROR\",\"INVALID_CREDENTIALS\")\n| summarize dcount(actor_alternateId_s) by client_ipAddress_s, bin(TimeGenerated, 5m)\n| where dcount_actor_alternateId_s > FailureThreshold\n| project client_ipAddress_s, TimeGenerated;\nOkta_CL\n| where eventType_s =~ \"user.session.start\"and outcome_reason_s in (\"VERIFICATION_ERROR\",\"INVALID_CREDENTIALS\")\n| summarize Users = make_set(actor_alternateId_s) by client_ipAddress_s, City = client_geographicalContext_city_s, Country = client_geographicalContext_country_s, bin(TimeGenerated, 5m)\n| join kind=inner (FailedEvents) on client_ipAddress_s, TimeGenerated\n| sort by TimeGenerated desc\n| extend timestamp = TimeGenerated, IPCustomEntity = client_ipAddress_s\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "tactics": [
          "CredentialAccess"
        ]
      }
    }
  ]
}