{
  "$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/284c73e0-3e14-4698-9202-36fcd458034e')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/284c73e0-3e14-4698-9202-36fcd458034e')]",
      "properties": {
        "alertRuleTemplateName": "284c73e0-3e14-4698-9202-36fcd458034e",
        "customDetails": null,
        "description": "Identifies users with several AADSTS50074 (strong authentication required, the user did not pass the MFA challenge) or AADSTS500121 (authentication failed during the MFA challenge) sign-in results from the same IP address within one hour.\nOne such row is often normal, for example a user who ignores a prompt once. A burst from an IP or country the user does not use can indicate MFA fatigue (an attacker with the password generating prompts), and a later successful sign-in from the same IP suggests the user approved a prompt they did not start.\nThe threshold of 3 is a starting point, not a Microsoft number. Tune it against your own baseline.\nEach run looks at the last hour only, matching the hourly schedule, so one burst raises one alert and not one per run.\nReference: https://learn.microsoft.com/en-us/entra/identity/monitoring-health/concept-interactive-sign-ins\n",
        "displayName": "Repeated failed MFA challenges for one user from one IP (AADSTS50074 / AADSTS500121)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UserPrincipalName",
                "identifier": "FullName"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "IPAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SigninLogs/MFAPromptBurstFromSingleIP.yaml",
        "query": "SigninLogs\n| where TimeGenerated > ago(1h)\n| where ResultType in (\"50074\", \"500121\")\n| summarize Prompts = count(),\n            ResultTypes = make_set(ResultType),\n            FirstSeen = min(CreatedDateTime),\n            LastSeen = max(CreatedDateTime),\n            Apps = make_set(AppDisplayName, 5)\n          by UserPrincipalName, IPAddress\n| where Prompts >= 3\n| sort by Prompts desc\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "InPreview",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "techniques": [
          "T1621"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}