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);
ThreatIntelIndicators
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
| where isnotempty(IndicatorType) and IndicatorType == "email-addr"
| extend EmailSenderAddress = ObservableValue
| extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, "@") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, "@") - 1)
| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
| where isnotempty(EmailSenderAddress)
| extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
| where TimeGenerated >= ago(ioc_lookBack)
// | where tolower(EmailSenderAddress) in (OfficeActivityUPNs)
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
| where IsActive == true and ValidUntil > now()
| extend Description = tostring(parse_json(Data).description)
| where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;"
| project-reorder *, TrafficLightProtocolLevel, EmailSenderAddress, EmailSourceDomain, Type
// 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 < ValidUntil
| summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by Id, UserId
| extend Description = tostring(parse_json(Data).description)
| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
| project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, EmailSenderAddress, EmailSourceDomain, UserId, ClientIP, Operation, UserType, RecordType, OfficeWorkload, Parameters, Url//, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType
| extend Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])
| extend timestamp = OfficeActivity_TimeGenerated

OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence (NEW)/Analytic Rules/EmailEntity_OfficeActivity.yaml
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);
  ThreatIntelIndicators
  | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
  | where isnotempty(IndicatorType) and IndicatorType == "email-addr"
  | extend EmailSenderAddress = ObservableValue
  | extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, "@") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, "@") - 1)
  | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
  | where isnotempty(EmailSenderAddress)
  | extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
  | where TimeGenerated >= ago(ioc_lookBack)
  // | where tolower(EmailSenderAddress) in (OfficeActivityUPNs)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
  | where IsActive == true and ValidUntil > now()
  | extend Description = tostring(parse_json(Data).description)
  | where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;"
  | project-reorder *, TrafficLightProtocolLevel, EmailSenderAddress, EmailSourceDomain, Type
  // 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 < ValidUntil
  | summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by Id, UserId
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, EmailSenderAddress, EmailSourceDomain, UserId, ClientIP, Operation, UserType, RecordType, OfficeWorkload, Parameters, Url//, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType
  | extend Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])
  | extend timestamp = OfficeActivity_TimeGenerated  
description: |
    'Identifies a match in OfficeActivity table from any Email IOC from TI'
severity: Medium
requiredDataConnectors:
- dataTypes:
  - OfficeActivity
  connectorId: Office365
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
name: TI map Email entity to OfficeActivity
triggerThreshold: 0
tactics:
- InitialAccess
version: 1.2.8
relevantTechniques:
- T1566
triggerOperator: gt
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
id: 795d43a3-6edc-4c99-971f-00d05841e5ac
kind: Scheduled
queryFrequency: 1h
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/795d43a3-6edc-4c99-971f-00d05841e5ac')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/795d43a3-6edc-4c99-971f-00d05841e5ac')]",
      "properties": {
        "alertRuleTemplateName": "795d43a3-6edc-4c99-971f-00d05841e5ac",
        "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 (NEW)/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);\nThreatIntelIndicators\n| extend IndicatorType = replace(@\"\\[|\\]|\\\"\"\", \"\", tostring(split(ObservableKey, \":\", 0)))\n| where isnotempty(IndicatorType) and IndicatorType == \"email-addr\"\n| extend EmailSenderAddress = ObservableValue\n| extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, \"@\") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, \"@\") - 1)\n| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)\n| where isnotempty(EmailSenderAddress)\n| extend Url = iff(ObservableKey == \"url:value\", ObservableValue, \"\")\n| where TimeGenerated >= ago(ioc_lookBack)\n// | where tolower(EmailSenderAddress) in (OfficeActivityUPNs)\n| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id\n| where IsActive == true and ValidUntil > now()\n| extend Description = tostring(parse_json(Data).description)\n| where Description !contains_cs \"State: inactive;\" and Description !contains_cs \"State: falsepos;\"\n| project-reorder *, TrafficLightProtocolLevel, EmailSenderAddress, EmailSourceDomain, Type\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 < ValidUntil\n| summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by Id, UserId\n| extend Description = tostring(parse_json(Data).description)\n| extend ActivityGroupNames = extract(@\"ActivityGroup:(\\S+)\", 1, tostring(parse_json(Data).labels))\n| project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, EmailSenderAddress, EmailSourceDomain, UserId, ClientIP, Operation, UserType, RecordType, OfficeWorkload, Parameters, Url//, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType\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": "1.2.8",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}