Front Door Premium WAF - XSS Detection

let Threshold = 1;
AzureDiagnostics
| where Category =~ "FrontDoorWebApplicationFirewallLog"
| where action_s =~ "AnomalyScoring"
| where details_msg_s has "XSS"
| parse details_data_s with MessageText "Matched Data:" MatchedData "AND " * "table_name FROM " TableName " " *
| project trackingReference_s, host_s, requestUri_s, TimeGenerated, clientIP_s, details_matches_s, details_msg_s, details_data_s, TableName, MatchedData
| join kind = inner(
AzureDiagnostics
| where Category =~ "FrontDoorWebApplicationFirewallLog"
| where action_s =~ "Block") on trackingReference_s
| summarize URI_s = make_set(requestUri_s,100), Table = make_set(TableName,100), StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), TrackingReference = make_set(trackingReference_s,100), Matched_Data = make_set(MatchedData,100), Detail_Data = make_set(details_data_s,100), Detail_Message = make_set(details_msg_s,100), Total_TrackingReference = dcount(trackingReference_s) by clientIP_s, host_s, action_s
| where Total_TrackingReference >= Threshold

relevantTechniques:
- T1189
- T1203
- T0853
name: Front Door Premium WAF - XSS Detection
requiredDataConnectors:
- dataTypes:
  - AzureDiagnostics
  connectorId: WAF
entityMappings:
- fieldMappings:
  - identifier: Url
    columnName: URI_s
  entityType: URL
- fieldMappings:
  - identifier: Address
    columnName: clientIP_s
  entityType: IP
triggerThreshold: 0
id: b7643904-5081-4920-917e-a559ddc3448f
tactics:
- InitialAccess
- Execution
version: 1.0.2
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Web Application Firewall (WAF)/Analytic Rules/AFD-Premium-WAF-XSSDetection.yaml
queryPeriod: 6h
kind: Scheduled
tags:
- Cross Site Scripting
queryFrequency: 6h
severity: High
status: Available
description: |
  'Identifies a match for an XSS attack in the Front Door Premium WAF logs. The threshold value in the query can be changed as per your infrastructure's requirements.
   References: https://owasp.org/www-project-top-ten/2017/A7_2017-Cross-Site_Scripting_(XSS)'  
query: |
  let Threshold = 1;
  AzureDiagnostics
  | where Category =~ "FrontDoorWebApplicationFirewallLog"
  | where action_s =~ "AnomalyScoring"
  | where details_msg_s has "XSS"
  | parse details_data_s with MessageText "Matched Data:" MatchedData "AND " * "table_name FROM " TableName " " *
  | project trackingReference_s, host_s, requestUri_s, TimeGenerated, clientIP_s, details_matches_s, details_msg_s, details_data_s, TableName, MatchedData
  | join kind = inner(
  AzureDiagnostics
  | where Category =~ "FrontDoorWebApplicationFirewallLog"
  | where action_s =~ "Block") on trackingReference_s
  | summarize URI_s = make_set(requestUri_s,100), Table = make_set(TableName,100), StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), TrackingReference = make_set(trackingReference_s,100), Matched_Data = make_set(MatchedData,100), Detail_Data = make_set(details_data_s,100), Detail_Message = make_set(details_msg_s,100), Total_TrackingReference = dcount(trackingReference_s) by clientIP_s, host_s, action_s
  | where Total_TrackingReference >= Threshold  
triggerOperator: gt

{
  "$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/b7643904-5081-4920-917e-a559ddc3448f')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/b7643904-5081-4920-917e-a559ddc3448f')]",
      "properties": {
        "alertRuleTemplateName": "b7643904-5081-4920-917e-a559ddc3448f",
        "customDetails": null,
        "description": "'Identifies a match for an XSS attack in the Front Door Premium WAF logs. The threshold value in the query can be changed as per your infrastructure's requirements.\n References: https://owasp.org/www-project-top-ten/2017/A7_2017-Cross-Site_Scripting_(XSS)'\n",
        "displayName": "Front Door Premium WAF - XSS Detection",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "URL",
            "fieldMappings": [
              {
                "columnName": "URI_s",
                "identifier": "Url"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "clientIP_s",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Web Application Firewall (WAF)/Analytic Rules/AFD-Premium-WAF-XSSDetection.yaml",
        "query": "let Threshold = 1;\nAzureDiagnostics\n| where Category =~ \"FrontDoorWebApplicationFirewallLog\"\n| where action_s =~ \"AnomalyScoring\"\n| where details_msg_s has \"XSS\"\n| parse details_data_s with MessageText \"Matched Data:\" MatchedData \"AND \" * \"table_name FROM \" TableName \" \" *\n| project trackingReference_s, host_s, requestUri_s, TimeGenerated, clientIP_s, details_matches_s, details_msg_s, details_data_s, TableName, MatchedData\n| join kind = inner(\nAzureDiagnostics\n| where Category =~ \"FrontDoorWebApplicationFirewallLog\"\n| where action_s =~ \"Block\") on trackingReference_s\n| summarize URI_s = make_set(requestUri_s,100), Table = make_set(TableName,100), StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), TrackingReference = make_set(trackingReference_s,100), Matched_Data = make_set(MatchedData,100), Detail_Data = make_set(details_data_s,100), Detail_Message = make_set(details_msg_s,100), Total_TrackingReference = dcount(trackingReference_s) by clientIP_s, host_s, action_s\n| where Total_TrackingReference >= Threshold\n",
        "queryFrequency": "PT6H",
        "queryPeriod": "PT6H",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Execution",
          "InitialAccess"
        ],
        "tags": [
          "Cross Site Scripting"
        ],
        "techniques": [
          "T1189",
          "T1203"
        ],
        "templateVersion": "1.0.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}