Microsoft Sentinel Analytic Rules
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TI map Domain entity to Web Session Events ASIM Web Session schema

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Idb1832f60-6c3d-4722-a0a5-3d564ee61a63
RulenameTI map Domain entity to Web Session Events (ASIM Web Session schema)
DescriptionThis rule identifies Web Sessions for which the target URL hostname is a known IoC. This rule uses the Advanced Security Information Model (ASIM) and supports any web session source that complies with ASIM.
SeverityMedium
TacticsImpact
Required data connectorsMicrosoftDefenderThreatIntelligence
SquidProxy
ThreatIntelligence
ThreatIntelligenceTaxii
Zscaler
KindScheduled
Query frequency1h
Query period14d
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_imWebSession.yaml
Version1.0.5
Arm templateb1832f60-6c3d-4722-a0a5-3d564ee61a63.json
Deploy To Azure
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   
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.
triggerOperator: gt
tactics:
- Impact
queryPeriod: 14d
kind: Scheduled
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_imWebSession.yaml
queryFrequency: 1h
customDetails:
  IoCExpirationTime: ExpirationDateTime
  IndicatorId: IndicatorId
  ThreatType: ThreatType
  IoCDescription: Description
  EventTime: Event_TimeGenerated
  ActivityGroupNames: ActivityGroupNames
  IoCConfidenceScore: ConfidenceScore
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.'
requiredDataConnectors:
- dataTypes:
  - SquidProxy_CL
  connectorId: SquidProxy
- dataTypes:
  - CommonSecurityLog
  connectorId: Zscaler
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
version: 1.0.5
triggerThreshold: 0
severity: Medium
id: b1832f60-6c3d-4722-a0a5-3d564ee61a63
entityMappings:
- entityType: IP
  fieldMappings:
  - columnName: SrcIpAddr
    identifier: Address
- entityType: URL
  fieldMappings:
  - columnName: Url
    identifier: Url
name: TI map Domain entity to Web Session Events (ASIM Web Session schema)
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     
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-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",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact"
        ],
        "templateVersion": "1.0.5",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}