TI Map URL Entity to SecurityAlert Data

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let URLRegex = "((https?|ftp|ldap|wss?|file):\\/\\/(([\\:\\%\\w\\_\\-]+(\\.|@))*((xn--)?[a-zA-Z0-9\\-]+\\.)+(xn--[a-z0-9]+|[A-Za-z]+)|\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{0,3})[.,:\\w@?^=%&\\/~+#-]*[\\w@?^=%&\\/~+#-])";
let SecurityEvents = materialize(SecurityAlert
  | where TimeGenerated >= ago(dt_lookBack)
  | extend MSTI = case(AlertName has "TI map" and VendorName == "Microsoft" and ProductName == 'Azure Sentinel', true, false)
  | where MSTI == false
  // Extract URL from JSON data
  | mv-expand parse_json(Entities)
  | where isnotempty(Entities.Url) or isnotempty(Entities.Urls)
  | extend Url = coalesce(Entities.Url, Entities.Urls)
  | mv-expand Url
  | extend Url = tolower(Url)
  // Extract hostname from JSON data for entity mapping
  | extend Compromised_Host = tostring(parse_json(ExtendedProperties).["Compromised Host"])
  | extend Alert_TimeGenerated = TimeGenerated);
let EventUrls = materialize(SecurityEvents | distinct Url | summarize make_list(Url));
ThreatIntelligenceIndicator
| where isnotempty(Url)
| where TimeGenerated >= ago(ioc_lookBack)
| extend Url = tolower(Url)
| where tolower(Url) in (EventUrls)
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
| where Active == true and ExpirationDateTime > now()
| where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;" 
// using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
| join kind=innerunique (SecurityEvents) on Url
| where Alert_TimeGenerated < ExpirationDateTime
| summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by IndicatorId, AlertName
| project timestamp = Alert_TimeGenerated, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, AlertName, AlertSeverity, Description, Url, Compromised_Host

relevantTechniques:
- T1071
name: TI Map URL Entity to SecurityAlert Data
requiredDataConnectors:
- dataTypes:
  - SecurityAlert
  connectorId: MicrosoftCloudAppSecurity
- dataTypes:
  - SecurityAlert
  connectorId: AzureSecurityCenter
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
entityMappings:
- fieldMappings:
  - identifier: HostName
    columnName: Compromised_Host
  entityType: Host
- fieldMappings:
  - identifier: Url
    columnName: Url
  entityType: URL
triggerThreshold: 0
id: f30a47c1-65fb-42b1-a7f4-00941c12550b
tactics:
- CommandAndControl
version: 1.2.8
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/URLEntity_SecurityAlerts.yaml
queryPeriod: 14d
kind: Scheduled
queryFrequency: 1h
severity: Medium
description: |
    'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in SecurityAlert data.'
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let URLRegex = "((https?|ftp|ldap|wss?|file):\\/\\/(([\\:\\%\\w\\_\\-]+(\\.|@))*((xn--)?[a-zA-Z0-9\\-]+\\.)+(xn--[a-z0-9]+|[A-Za-z]+)|\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{0,3})[.,:\\w@?^=%&\\/~+#-]*[\\w@?^=%&\\/~+#-])";
  let SecurityEvents = materialize(SecurityAlert
    | where TimeGenerated >= ago(dt_lookBack)
    | extend MSTI = case(AlertName has "TI map" and VendorName == "Microsoft" and ProductName == 'Azure Sentinel', true, false)
    | where MSTI == false
    // Extract URL from JSON data
    | mv-expand parse_json(Entities)
    | where isnotempty(Entities.Url) or isnotempty(Entities.Urls)
    | extend Url = coalesce(Entities.Url, Entities.Urls)
    | mv-expand Url
    | extend Url = tolower(Url)
    // Extract hostname from JSON data for entity mapping
    | extend Compromised_Host = tostring(parse_json(ExtendedProperties).["Compromised Host"])
    | extend Alert_TimeGenerated = TimeGenerated);
  let EventUrls = materialize(SecurityEvents | distinct Url | summarize make_list(Url));
  ThreatIntelligenceIndicator
  | where isnotempty(Url)
  | where TimeGenerated >= ago(ioc_lookBack)
  | extend Url = tolower(Url)
  | where tolower(Url) in (EventUrls)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now()
  | where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;" 
  // using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
  | join kind=innerunique (SecurityEvents) on Url
  | where Alert_TimeGenerated < ExpirationDateTime
  | summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by IndicatorId, AlertName
  | project timestamp = Alert_TimeGenerated, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, AlertName, AlertSeverity, Description, Url, Compromised_Host  
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/f30a47c1-65fb-42b1-a7f4-00941c12550b')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/f30a47c1-65fb-42b1-a7f4-00941c12550b')]",
      "properties": {
        "alertRuleTemplateName": "f30a47c1-65fb-42b1-a7f4-00941c12550b",
        "customDetails": null,
        "description": "'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in SecurityAlert data.'\n",
        "displayName": "TI Map URL Entity to SecurityAlert Data",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Compromised_Host",
                "identifier": "HostName"
              }
            ]
          },
          {
            "entityType": "URL",
            "fieldMappings": [
              {
                "columnName": "Url",
                "identifier": "Url"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/URLEntity_SecurityAlerts.yaml",
        "query": "let dt_lookBack = 1h;\nlet ioc_lookBack = 14d;\nlet URLRegex = \"((https?|ftp|ldap|wss?|file):\\\\/\\\\/(([\\\\:\\\\%\\\\w\\\\_\\\\-]+(\\\\.|@))*((xn--)?[a-zA-Z0-9\\\\-]+\\\\.)+(xn--[a-z0-9]+|[A-Za-z]+)|\\\\d{1,3}\\\\.\\\\d{1,3}\\\\.\\\\d{1,3}\\\\.\\\\d{0,3})[.,:\\\\w@?^=%&\\\\/~+#-]*[\\\\w@?^=%&\\\\/~+#-])\";\nlet SecurityEvents = materialize(SecurityAlert\n  | where TimeGenerated >= ago(dt_lookBack)\n  | extend MSTI = case(AlertName has \"TI map\" and VendorName == \"Microsoft\" and ProductName == 'Azure Sentinel', true, false)\n  | where MSTI == false\n  // Extract URL from JSON data\n  | mv-expand parse_json(Entities)\n  | where isnotempty(Entities.Url) or isnotempty(Entities.Urls)\n  | extend Url = coalesce(Entities.Url, Entities.Urls)\n  | mv-expand Url\n  | extend Url = tolower(Url)\n  // Extract hostname from JSON data for entity mapping\n  | extend Compromised_Host = tostring(parse_json(ExtendedProperties).[\"Compromised Host\"])\n  | extend Alert_TimeGenerated = TimeGenerated);\nlet EventUrls = materialize(SecurityEvents | distinct Url | summarize make_list(Url));\nThreatIntelligenceIndicator\n| where isnotempty(Url)\n| where TimeGenerated >= ago(ioc_lookBack)\n| extend Url = tolower(Url)\n| where tolower(Url) in (EventUrls)\n| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId\n| where Active == true and ExpirationDateTime > now()\n| where Description !contains_cs \"State: inactive;\" and Description !contains_cs \"State: falsepos;\" \n// using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated\n| join kind=innerunique (SecurityEvents) on Url\n| where Alert_TimeGenerated < ExpirationDateTime\n| summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by IndicatorId, AlertName\n| project timestamp = Alert_TimeGenerated, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, AlertName, AlertSeverity, Description, Url, Compromised_Host\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "techniques": [
          "T1071"
        ],
        "templateVersion": "1.2.8",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}