TI map Email entity to Cloud App Events

let dt_lookBack = 10d;
let ioc_lookBack = 30d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
ThreatIntelIndicators
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
  | where IsActive == true and ValidUntil > now()
//extract key part of kv pair
  | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
  | where isnotempty(IndicatorType) and IndicatorType == "email-addr"
  | extend EmailSenderAddress = ObservableValue
  | where isnotempty(EmailSenderAddress)
  | extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, "@") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, "@") - 1)
  | project-reorder *, EmailSenderAddress, EmailSourceDomain, Type
  | extend IndicatorId = tostring(split(Id, "--")[2])
  | join kind=innerunique (CloudAppEvents
| extend User_Id = tostring(RawEventData.UserId)
| where isnotempty(User_Id)
| where TimeGenerated >= ago(dt_lookBack) and isnotempty(Application)
| extend CloudAppEvents_TimeGenerated = TimeGenerated 
| where User_Id matches regex emailregex) on $left.EmailSenderAddress == $right.User_Id
| where CloudAppEvents_TimeGenerated < ValidUntil
| summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId, User_Id
| extend Name = tostring(split(User_Id, '@', 0)[0]), UPNSuffix = tostring(split(User_Id, '@', 1)[0])
| extend timestamp = CloudAppEvents_TimeGenerated

id: 0385e99c-ae45-45f4-aecf-00104485cd6b
triggerOperator: gt
entityMappings:
- fieldMappings:
  - identifier: DisplayName
    columnName: Name
  - identifier: FullName
    columnName: User_Id
  - identifier: UPNSuffix
    columnName: UPNSuffix
  entityType: Account
description: |
    'Identifies compromises and attacks and detect malicious activities in one's email entity from TI'
severity: Medium
version: 1.0.4
relevantTechniques:
- T1566
tactics:
- InitialAccess
name: TI map Email entity to Cloud App Events
queryFrequency: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence (NEW)/Analytic Rules/EmailEntity_CloudAppEvents_Updated.yaml
query: |
  let dt_lookBack = 10d;
  let ioc_lookBack = 30d;
  let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
  ThreatIntelIndicators
    | where TimeGenerated >= ago(ioc_lookBack)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
    | where IsActive == true and ValidUntil > now()
  //extract key part of kv pair
    | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
    | where isnotempty(IndicatorType) and IndicatorType == "email-addr"
    | extend EmailSenderAddress = ObservableValue
    | where isnotempty(EmailSenderAddress)
    | extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, "@") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, "@") - 1)
    | project-reorder *, EmailSenderAddress, EmailSourceDomain, Type
    | extend IndicatorId = tostring(split(Id, "--")[2])
    | join kind=innerunique (CloudAppEvents
  | extend User_Id = tostring(RawEventData.UserId)
  | where isnotempty(User_Id)
  | where TimeGenerated >= ago(dt_lookBack) and isnotempty(Application)
  | extend CloudAppEvents_TimeGenerated = TimeGenerated 
  | where User_Id matches regex emailregex) on $left.EmailSenderAddress == $right.User_Id
  | where CloudAppEvents_TimeGenerated < ValidUntil
  | summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId, User_Id
  | extend Name = tostring(split(User_Id, '@', 0)[0]), UPNSuffix = tostring(split(User_Id, '@', 1)[0])
  | extend timestamp = CloudAppEvents_TimeGenerated  
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- dataTypes:
  - CloudAppEvents
  connectorId: MicrosoftThreatProtection
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
queryPeriod: 14d

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/0385e99c-ae45-45f4-aecf-00104485cd6b')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/0385e99c-ae45-45f4-aecf-00104485cd6b')]",
      "properties": {
        "alertRuleTemplateName": "0385e99c-ae45-45f4-aecf-00104485cd6b",
        "customDetails": null,
        "description": "'Identifies compromises and attacks and detect malicious activities in one's email entity from TI'\n",
        "displayName": "TI map Email entity to Cloud App Events",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "Name",
                "identifier": "DisplayName"
              },
              {
                "columnName": "User_Id",
                "identifier": "FullName"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence (NEW)/Analytic Rules/EmailEntity_CloudAppEvents_Updated.yaml",
        "query": "let dt_lookBack = 10d;\nlet ioc_lookBack = 30d;\nlet emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$';\nThreatIntelIndicators\n  | where TimeGenerated >= ago(ioc_lookBack)\n  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id\n  | where IsActive == true and ValidUntil > now()\n//extract key part of kv pair\n  | extend IndicatorType = replace(@\"\\[|\\]|\\\"\"\", \"\", tostring(split(ObservableKey, \":\", 0)))\n  | where isnotempty(IndicatorType) and IndicatorType == \"email-addr\"\n  | extend EmailSenderAddress = ObservableValue\n  | where isnotempty(EmailSenderAddress)\n  | extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, \"@\") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, \"@\") - 1)\n  | project-reorder *, EmailSenderAddress, EmailSourceDomain, Type\n  | extend IndicatorId = tostring(split(Id, \"--\")[2])\n  | join kind=innerunique (CloudAppEvents\n| extend User_Id = tostring(RawEventData.UserId)\n| where isnotempty(User_Id)\n| where TimeGenerated >= ago(dt_lookBack) and isnotempty(Application)\n| extend CloudAppEvents_TimeGenerated = TimeGenerated \n| where User_Id matches regex emailregex) on $left.EmailSenderAddress == $right.User_Id\n| where CloudAppEvents_TimeGenerated < ValidUntil\n| summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId, User_Id\n| extend Name = tostring(split(User_Id, '@', 0)[0]), UPNSuffix = tostring(split(User_Id, '@', 1)[0])\n| extend timestamp = CloudAppEvents_TimeGenerated\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1566"
        ],
        "templateVersion": "1.0.4",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}