TI map Email entity to OfficeActivity

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
let OfficeEvents = materialize(
  OfficeActivity
  | where isnotempty(UserId)
  | where TimeGenerated >= ago(dt_lookBack)
  | where UserId matches regex emailregex
  | project-rename  OfficeActivity_TimeGenerated = TimeGenerated);
let OfficeActivityUPNs = OfficeEvents | distinct UserId = tolower(UserId) | summarize make_list(UserId);
ThreatIntelligenceIndicator
| where isnotempty(EmailSenderAddress)
| where TimeGenerated >= ago(ioc_lookBack)
| where tolower(EmailSenderAddress) in (OfficeActivityUPNs)
| 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 (OfficeEvents) on $left.EmailSenderAddress == $right.UserId
| where OfficeActivity_TimeGenerated < ExpirationDateTime
| summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by IndicatorId, UserId
| project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore, EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, UserId, ClientIP, Operation, UserType, RecordType, OfficeWorkload, Parameters
| extend Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])
| extend timestamp = OfficeActivity_TimeGenerated

relevantTechniques:
- T1566
name: TI map Email entity to OfficeActivity
requiredDataConnectors:
- dataTypes:
  - OfficeActivity
  connectorId: Office365
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: UserId
  - identifier: Name
    columnName: Name
  - identifier: UPNSuffix
    columnName: UPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: ClientIP
  entityType: IP
- fieldMappings:
  - identifier: Url
    columnName: Url
  entityType: URL
triggerThreshold: 0
id: 4a3f5ed7-8da5-4ce2-af6f-c9ada45060f2
tactics:
- InitialAccess
version: 1.2.7
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/EmailEntity_OfficeActivity.yaml
queryPeriod: 14d
kind: Scheduled
queryFrequency: 1h
severity: Medium
description: |
    'Identifies a match in OfficeActivity table from any Email IOC from TI'
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
  let OfficeEvents = materialize(
    OfficeActivity
    | where isnotempty(UserId)
    | where TimeGenerated >= ago(dt_lookBack)
    | where UserId matches regex emailregex
    | project-rename  OfficeActivity_TimeGenerated = TimeGenerated);
  let OfficeActivityUPNs = OfficeEvents | distinct UserId = tolower(UserId) | summarize make_list(UserId);
  ThreatIntelligenceIndicator
  | where isnotempty(EmailSenderAddress)
  | where TimeGenerated >= ago(ioc_lookBack)
  | where tolower(EmailSenderAddress) in (OfficeActivityUPNs)
  | 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 (OfficeEvents) on $left.EmailSenderAddress == $right.UserId
  | where OfficeActivity_TimeGenerated < ExpirationDateTime
  | summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by IndicatorId, UserId
  | project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore, EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, UserId, ClientIP, Operation, UserType, RecordType, OfficeWorkload, Parameters
  | extend Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])
  | extend timestamp = OfficeActivity_TimeGenerated  
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/4a3f5ed7-8da5-4ce2-af6f-c9ada45060f2')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/4a3f5ed7-8da5-4ce2-af6f-c9ada45060f2')]",
      "properties": {
        "alertRuleTemplateName": "4a3f5ed7-8da5-4ce2-af6f-c9ada45060f2",
        "customDetails": null,
        "description": "'Identifies a match in OfficeActivity table from any Email IOC from TI'\n",
        "displayName": "TI map Email entity to OfficeActivity",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UserId",
                "identifier": "FullName"
              },
              {
                "columnName": "Name",
                "identifier": "Name"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "ClientIP",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "URL",
            "fieldMappings": [
              {
                "columnName": "Url",
                "identifier": "Url"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/EmailEntity_OfficeActivity.yaml",
        "query": "let dt_lookBack = 1h;\nlet ioc_lookBack = 14d;\nlet emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$';\nlet OfficeEvents = materialize(\n  OfficeActivity\n  | where isnotempty(UserId)\n  | where TimeGenerated >= ago(dt_lookBack)\n  | where UserId matches regex emailregex\n  | project-rename  OfficeActivity_TimeGenerated = TimeGenerated);\nlet OfficeActivityUPNs = OfficeEvents | distinct UserId = tolower(UserId) | summarize make_list(UserId);\nThreatIntelligenceIndicator\n| where isnotempty(EmailSenderAddress)\n| where TimeGenerated >= ago(ioc_lookBack)\n| where tolower(EmailSenderAddress) in (OfficeActivityUPNs)\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 (OfficeEvents) on $left.EmailSenderAddress == $right.UserId\n| where OfficeActivity_TimeGenerated < ExpirationDateTime\n| summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by IndicatorId, UserId\n| project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore, EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, UserId, ClientIP, Operation, UserType, RecordType, OfficeWorkload, Parameters\n| extend Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])\n| extend timestamp = OfficeActivity_TimeGenerated\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1566"
        ],
        "templateVersion": "1.2.7",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}