TI map Domain entity to SecurityAlert

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let IoCList = externaldata(TimeGenerated:datetime,IoC:string,IoC_Type:string,ExpirationDateTime:datetime,Description:string,Action:string, ConfidenceScore:real, ThreatType:string, Active:string,Type:string, TrafficLightProtocolLevel:string, ActivityGroupNames:string)[@"https://raw.githubusercontent.com/microsoft/mstic/master/RapidReleaseTI/Indicators.csv"] with(format="csv", ignoreFirstRecord=True);
//Create a list of TLDs in our threat feed for later validation
let list_tlds = ThreatIntelligenceIndicator
| where TimeGenerated > ago(ioc_lookBack)
| where isnotempty(DomainName)
| extend parts = split(DomainName, '.')
| extend tld = parts[(array_length(parts)-1)]
| summarize count() by tostring(tld)
| summarize make_list(tld);
let Domain_Indicators = (union isfuzzy=true
(ThreatIntelligenceIndicator
| where TimeGenerated >= ago(ioc_lookBack) and ExpirationDateTime > now()
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
| where Active == true
// Picking up only IOC's that contain the entities we want
| where isnotempty(DomainName)
| extend TI_DomainEntity = DomainName
),
(IoCList
| where IoC_Type =~ 'domainname'
| where ExpirationDateTime > now()
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IoC
| where Active =~ 'True'
| extend TI_DomainEntity = IoC
| project-away  IoC_Type
)
);
Domain_Indicators
// 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 (
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 domain patterns from message
| extend domain = todynamic(dynamic_to_json(extract_all(@"(((xn--)?[a-z0-9\-]+\.)+([a-z]+|(xn--[a-z0-9]+)))", dynamic([1]), tolower(Entities))))
| mv-expand domain
| extend domain = tostring(domain[0])
| extend parts = split(domain, '.')
//Split out the TLD
| extend tld = parts[(array_length(parts)-1)]
//Validate parsed domain by checking if the TLD is in the list of TLDs in our threat feed
| where tld in~ (list_tlds)
// Converting Entities into dynamic data type and use mv-expand to unpack the array
| extend EntitiesDynamicArray = parse_json(Entities)
| mv-apply EntitiesDynamicArray on
(summarize
HostName = take_anyif(tostring(EntitiesDynamicArray.HostName), EntitiesDynamicArray.Type == "host"),
IP_addr = take_anyif(tostring(EntitiesDynamicArray.Address), EntitiesDynamicArray.Type == "ip")
)
| extend Alert_TimeGenerated = TimeGenerated
| extend Alert_Description = Description
) on $left.TI_DomainEntity==$right.domain
| where Alert_TimeGenerated < ExpirationDateTime
| summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by IndicatorId, AlertName, IoC
| project Alert_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, DomainName, AlertName, Alert_Description, ProviderName, AlertSeverity, ConfidenceLevel, HostName, IP_addr, Url, Entities, Type, IoC, TI_DomainEntity
| extend timestamp = Alert_TimeGenerated, HostCustomEntity = HostName, IPCustomEntity = IP_addr, URLCustomEntity = Url

triggerOperator: gt
id: 87890d78-3e05-43ec-9ab9-ba32f4e01250
queryFrequency: 1h
entityMappings:
- entityType: Host
  fieldMappings:
  - columnName: HostCustomEntity
    identifier: FullName
- entityType: IP
  fieldMappings:
  - columnName: IPCustomEntity
    identifier: Address
- entityType: URL
  fieldMappings:
  - columnName: URLCustomEntity
    identifier: Url
requiredDataConnectors:
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - SecurityAlert
  connectorId: MicrosoftCloudAppSecurity
- dataTypes:
  - SecurityAlert
  connectorId: AzureSecurityCenter
severity: Medium
triggerThreshold: 0
kind: Scheduled
queryPeriod: 14d
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_SecurityAlert.yaml
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let IoCList = externaldata(TimeGenerated:datetime,IoC:string,IoC_Type:string,ExpirationDateTime:datetime,Description:string,Action:string, ConfidenceScore:real, ThreatType:string, Active:string,Type:string, TrafficLightProtocolLevel:string, ActivityGroupNames:string)[@"https://raw.githubusercontent.com/microsoft/mstic/master/RapidReleaseTI/Indicators.csv"] with(format="csv", ignoreFirstRecord=True);
  //Create a list of TLDs in our threat feed for later validation
  let list_tlds = ThreatIntelligenceIndicator
  | where TimeGenerated > ago(ioc_lookBack)
  | where isnotempty(DomainName)
  | extend parts = split(DomainName, '.')
  | extend tld = parts[(array_length(parts)-1)]
  | summarize count() by tostring(tld)
  | summarize make_list(tld);
  let Domain_Indicators = (union isfuzzy=true
  (ThreatIntelligenceIndicator
  | where TimeGenerated >= ago(ioc_lookBack) and ExpirationDateTime > now()
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true
  // Picking up only IOC's that contain the entities we want
  | where isnotempty(DomainName)
  | extend TI_DomainEntity = DomainName
  ),
  (IoCList
  | where IoC_Type =~ 'domainname'
  | where ExpirationDateTime > now()
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IoC
  | where Active =~ 'True'
  | extend TI_DomainEntity = IoC
  | project-away  IoC_Type
  )
  );
  Domain_Indicators
  // 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 (
  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 domain patterns from message
  | extend domain = todynamic(dynamic_to_json(extract_all(@"(((xn--)?[a-z0-9\-]+\.)+([a-z]+|(xn--[a-z0-9]+)))", dynamic([1]), tolower(Entities))))
  | mv-expand domain
  | extend domain = tostring(domain[0])
  | extend parts = split(domain, '.')
  //Split out the TLD
  | extend tld = parts[(array_length(parts)-1)]
  //Validate parsed domain by checking if the TLD is in the list of TLDs in our threat feed
  | where tld in~ (list_tlds)
  // Converting Entities into dynamic data type and use mv-expand to unpack the array
  | extend EntitiesDynamicArray = parse_json(Entities)
  | mv-apply EntitiesDynamicArray on
  (summarize
  HostName = take_anyif(tostring(EntitiesDynamicArray.HostName), EntitiesDynamicArray.Type == "host"),
  IP_addr = take_anyif(tostring(EntitiesDynamicArray.Address), EntitiesDynamicArray.Type == "ip")
  )
  | extend Alert_TimeGenerated = TimeGenerated
  | extend Alert_Description = Description
  ) on $left.TI_DomainEntity==$right.domain
  | where Alert_TimeGenerated < ExpirationDateTime
  | summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by IndicatorId, AlertName, IoC
  | project Alert_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, DomainName, AlertName, Alert_Description, ProviderName, AlertSeverity, ConfidenceLevel, HostName, IP_addr, Url, Entities, Type, IoC, TI_DomainEntity
  | extend timestamp = Alert_TimeGenerated, HostCustomEntity = HostName, IPCustomEntity = IP_addr, URLCustomEntity = Url  
description: |
    'Identifies a match in SecurityAlert table from any Domain IOC from TI'
name: TI map Domain entity to SecurityAlert
tactics:
- Impact
version: 1.3.3

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/87890d78-3e05-43ec-9ab9-ba32f4e01250')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/87890d78-3e05-43ec-9ab9-ba32f4e01250')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "TI map Domain entity to SecurityAlert",
        "description": "'Identifies a match in SecurityAlert table from any Domain IOC from TI'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "let dt_lookBack = 1h;\nlet ioc_lookBack = 14d;\nlet IoCList = externaldata(TimeGenerated:datetime,IoC:string,IoC_Type:string,ExpirationDateTime:datetime,Description:string,Action:string, ConfidenceScore:real, ThreatType:string, Active:string,Type:string, TrafficLightProtocolLevel:string, ActivityGroupNames:string)[@\"https://raw.githubusercontent.com/microsoft/mstic/master/RapidReleaseTI/Indicators.csv\"] with(format=\"csv\", ignoreFirstRecord=True);\n//Create a list of TLDs in our threat feed for later validation\nlet list_tlds = ThreatIntelligenceIndicator\n| where TimeGenerated > ago(ioc_lookBack)\n| where isnotempty(DomainName)\n| extend parts = split(DomainName, '.')\n| extend tld = parts[(array_length(parts)-1)]\n| summarize count() by tostring(tld)\n| summarize make_list(tld);\nlet Domain_Indicators = (union isfuzzy=true\n(ThreatIntelligenceIndicator\n| where TimeGenerated >= ago(ioc_lookBack) and ExpirationDateTime > now()\n| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId\n| where Active == true\n// Picking up only IOC's that contain the entities we want\n| where isnotempty(DomainName)\n| extend TI_DomainEntity = DomainName\n),\n(IoCList\n| where IoC_Type =~ 'domainname'\n| where ExpirationDateTime > now()\n| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IoC\n| where Active =~ 'True'\n| extend TI_DomainEntity = IoC\n| project-away  IoC_Type\n)\n);\nDomain_Indicators\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 (\nSecurityAlert\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 domain patterns from message\n| extend domain = todynamic(dynamic_to_json(extract_all(@\"(((xn--)?[a-z0-9\\-]+\\.)+([a-z]+|(xn--[a-z0-9]+)))\", dynamic([1]), tolower(Entities))))\n| mv-expand domain\n| extend domain = tostring(domain[0])\n| extend parts = split(domain, '.')\n//Split out the TLD\n| extend tld = parts[(array_length(parts)-1)]\n//Validate parsed domain by checking if the TLD is in the list of TLDs in our threat feed\n| where tld in~ (list_tlds)\n// Converting Entities into dynamic data type and use mv-expand to unpack the array\n| extend EntitiesDynamicArray = parse_json(Entities)\n| mv-apply EntitiesDynamicArray on\n(summarize\nHostName = take_anyif(tostring(EntitiesDynamicArray.HostName), EntitiesDynamicArray.Type == \"host\"),\nIP_addr = take_anyif(tostring(EntitiesDynamicArray.Address), EntitiesDynamicArray.Type == \"ip\")\n)\n| extend Alert_TimeGenerated = TimeGenerated\n| extend Alert_Description = Description\n) on $left.TI_DomainEntity==$right.domain\n| where Alert_TimeGenerated < ExpirationDateTime\n| summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by IndicatorId, AlertName, IoC\n| project Alert_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, DomainName, AlertName, Alert_Description, ProviderName, AlertSeverity, ConfidenceLevel, HostName, IP_addr, Url, Entities, Type, IoC, TI_DomainEntity\n| extend timestamp = Alert_TimeGenerated, HostCustomEntity = HostName, IPCustomEntity = IP_addr, URLCustomEntity = Url\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact"
        ],
        "alertRuleTemplateName": "87890d78-3e05-43ec-9ab9-ba32f4e01250",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "HostCustomEntity"
              }
            ],
            "entityType": "Host"
          },
          {
            "fieldMappings": [
              {
                "identifier": "Address",
                "columnName": "IPCustomEntity"
              }
            ],
            "entityType": "IP"
          },
          {
            "fieldMappings": [
              {
                "identifier": "Url",
                "columnName": "URLCustomEntity"
              }
            ],
            "entityType": "URL"
          }
        ],
        "templateVersion": "1.3.3",
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_SecurityAlert.yaml"
      }
    }
  ]
}