TI map Domain entity to Web Session Events ASIM Web Session schema

let HAS_ANY_MAX = 10000;
let dt_lookBack = 1h;
let ioc_lookBack = 14d;
//Create a list of TLDs in our threat feed for later validation
let DOMAIN_TI=ThreatIntelligenceIndicator
// Picking up only IOC's that contain the entities we want
| where isnotempty(DomainName)
| where TimeGenerated >= ago(ioc_lookBack)
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
| where Active == true and ExpirationDateTime > now();
let DOMAIN_TI_list= todynamic(toscalar(DOMAIN_TI | summarize NIoCs = dcount(DomainName), Domains = make_set(DomainName) 
  | project Domains=iff(NIoCs > HAS_ANY_MAX, dynamic([]), Domains) ));
DOMAIN_TI
// 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 (
    _Im_WebSession(starttime=ago(dt_lookBack), url_has_any= DOMAIN_TI_list )
    //Extract domain patterns from syslog message
    | extend domain = tostring(parse_url(Url)["Host"])
    | where isnotempty(domain)
    | extend tld = tostring(split(domain, '.')[-1])
    | extend Event_TimeGenerated = TimeGenerated
) on $left.DomainName==$right.domain
| where Event_TimeGenerated < ExpirationDateTime
| summarize Event_TimeGenerated  = arg_max(Event_TimeGenerated , *) by IndicatorId, domain
| project Event_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, domain, SrcIpAddr, Url   

relevantTechniques:
- T1071
name: TI map Domain entity to Web Session Events (ASIM Web Session schema)
requiredDataConnectors:
- dataTypes:
  - SquidProxy_CL
  connectorId: SquidProxy
- dataTypes:
  - CommonSecurityLog
  connectorId: Zscaler
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
  entityType: IP
- fieldMappings:
  - identifier: Url
    columnName: Url
  entityType: URL
triggerThreshold: 0
id: b1832f60-6c3d-4722-a0a5-3d564ee61a63
tactics:
- CommandAndControl
version: 1.0.6
customDetails:
  IndicatorId: IndicatorId
  ThreatType: ThreatType
  IoCDescription: Description
  ActivityGroupNames: ActivityGroupNames
  EventTime: Event_TimeGenerated
  IoCConfidenceScore: ConfidenceScore
  IoCExpirationTime: ExpirationDateTime
alertDetailsOverride:
  alertDisplayNameFormat: A web request from {{SrcIpAddr}} to hostname  {{domain}} matched an IoC
  alertDescriptionFormat: A client with address {{SrcIpAddr}} requested the URL {{Url}}, whose hostname is a known indicator of compromise of {{ThreatType}}. Consult the threat intelligence blade for more information on the indicator.
queryPeriod: 14d
kind: Scheduled
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_imWebSession.yaml
queryFrequency: 1h
severity: Medium
description: |
    'This rule identifies Web Sessions for which the target URL hostname is a known IoC. This rule uses the [Advanced Security Information Model (ASIM)](https:/aka.ms/AboutASIM) and supports any web session source that complies with ASIM.'
query: |
  let HAS_ANY_MAX = 10000;
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  //Create a list of TLDs in our threat feed for later validation
  let DOMAIN_TI=ThreatIntelligenceIndicator
  // Picking up only IOC's that contain the entities we want
  | where isnotempty(DomainName)
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now();
  let DOMAIN_TI_list= todynamic(toscalar(DOMAIN_TI | summarize NIoCs = dcount(DomainName), Domains = make_set(DomainName) 
    | project Domains=iff(NIoCs > HAS_ANY_MAX, dynamic([]), Domains) ));
  DOMAIN_TI
  // 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 (
      _Im_WebSession(starttime=ago(dt_lookBack), url_has_any= DOMAIN_TI_list )
      //Extract domain patterns from syslog message
      | extend domain = tostring(parse_url(Url)["Host"])
      | where isnotempty(domain)
      | extend tld = tostring(split(domain, '.')[-1])
      | extend Event_TimeGenerated = TimeGenerated
  ) on $left.DomainName==$right.domain
  | where Event_TimeGenerated < ExpirationDateTime
  | summarize Event_TimeGenerated  = arg_max(Event_TimeGenerated , *) by IndicatorId, domain
  | project Event_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, domain, SrcIpAddr, Url     
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/b1832f60-6c3d-4722-a0a5-3d564ee61a63')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/b1832f60-6c3d-4722-a0a5-3d564ee61a63')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "A client with address {{SrcIpAddr}} requested the URL {{Url}}, whose hostname is a known indicator of compromise of {{ThreatType}}. Consult the threat intelligence blade for more information on the indicator.",
          "alertDisplayNameFormat": "A web request from {{SrcIpAddr}} to hostname  {{domain}} matched an IoC"
        },
        "alertRuleTemplateName": "b1832f60-6c3d-4722-a0a5-3d564ee61a63",
        "customDetails": {
          "ActivityGroupNames": "ActivityGroupNames",
          "EventTime": "Event_TimeGenerated",
          "IndicatorId": "IndicatorId",
          "IoCConfidenceScore": "ConfidenceScore",
          "IoCDescription": "Description",
          "IoCExpirationTime": "ExpirationDateTime",
          "ThreatType": "ThreatType"
        },
        "description": "'This rule identifies Web Sessions for which the target URL hostname is a known IoC. This rule uses the [Advanced Security Information Model (ASIM)](https:/aka.ms/AboutASIM) and supports any web session source that complies with ASIM.'\n",
        "displayName": "TI map Domain entity to Web Session Events (ASIM Web Session schema)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "URL",
            "fieldMappings": [
              {
                "columnName": "Url",
                "identifier": "Url"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_imWebSession.yaml",
        "query": "let HAS_ANY_MAX = 10000;\nlet dt_lookBack = 1h;\nlet ioc_lookBack = 14d;\n//Create a list of TLDs in our threat feed for later validation\nlet DOMAIN_TI=ThreatIntelligenceIndicator\n// Picking up only IOC's that contain the entities we want\n| where isnotempty(DomainName)\n| where TimeGenerated >= ago(ioc_lookBack)\n| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId\n| where Active == true and ExpirationDateTime > now();\nlet DOMAIN_TI_list= todynamic(toscalar(DOMAIN_TI | summarize NIoCs = dcount(DomainName), Domains = make_set(DomainName) \n  | project Domains=iff(NIoCs > HAS_ANY_MAX, dynamic([]), Domains) ));\nDOMAIN_TI\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 (\n    _Im_WebSession(starttime=ago(dt_lookBack), url_has_any= DOMAIN_TI_list )\n    //Extract domain patterns from syslog message\n    | extend domain = tostring(parse_url(Url)[\"Host\"])\n    | where isnotempty(domain)\n    | extend tld = tostring(split(domain, '.')[-1])\n    | extend Event_TimeGenerated = TimeGenerated\n) on $left.DomainName==$right.domain\n| where Event_TimeGenerated < ExpirationDateTime\n| summarize Event_TimeGenerated  = arg_max(Event_TimeGenerated , *) by IndicatorId, domain\n| project Event_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, domain, SrcIpAddr, Url   \n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "techniques": [
          "T1071"
        ],
        "templateVersion": "1.0.6",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}