TI map Email entity to SecurityEvent

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Id	2fc5d810-c9cc-491a-b564-841427ae0e50
Rulename	TI map Email entity to SecurityEvent
Description	Identifies a match in SecurityEvent table from any Email IOC from TI
Severity	Medium
Tactics	Impact
Required data connectors	MicrosoftDefenderThreatIntelligence SecurityEvents ThreatIntelligence ThreatIntelligenceTaxii WindowsForwardedEvents WindowsSecurityEvents
Kind	Scheduled
Query frequency	1h
Query period	14d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/EmailEntity_SecurityEvent.yaml
Version	1.3.4
Arm template	2fc5d810-c9cc-491a-b564-841427ae0e50.json

KQL

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
ThreatIntelligenceIndicator
| where TimeGenerated >= ago(ioc_lookBack) and ExpirationDateTime > now()
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
| where Active == true
//Filtering the table for Email related IOCs
| where isnotempty(EmailSenderAddress)
// 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 (
(union isfuzzy=true
(SecurityEvent
| where TimeGenerated >= ago(dt_lookBack) and isnotempty(TargetUserName)
//Normalizing the column to lower case for exact match with EmailSenderAddress column
| extend TargetUserName = tolower(TargetUserName)
// renaming timestamp column so it is clear the log this came from SecurityEvent table
| extend SecurityEvent_TimeGenerated = TimeGenerated
),
(WindowsEvent
| where TimeGenerated >= ago(dt_lookBack)
| extend TargetUserName = tostring(EventData.TargetUserName)
| where isnotempty(TargetUserName)
//Normalizing the column to lower case for exact match with EmailSenderAddress column
| extend TargetUserName = tolower(TargetUserName)
// renaming timestamp column so it is clear the log this came from SecurityEvent table
| extend SecurityEvent_TimeGenerated = TimeGenerated
))
)
on $left.EmailSenderAddress == $right.TargetUserName
| where SecurityEvent_TimeGenerated < ExpirationDateTime
| summarize SecurityEvent_TimeGenerated = arg_max(SecurityEvent_TimeGenerated, *) by IndicatorId, TargetUserName
| project SecurityEvent_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore,
EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, Computer, EventID, TargetUserName, Activity, IpAddress, AccountType,
LogonTypeName, LogonProcessName, Status, SubStatus
| extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
| extend timestamp = SecurityEvent_TimeGenerated

YAML

severity: Medium
queryFrequency: 1h
triggerOperator: gt
tactics:
- Impact
kind: Scheduled
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
  ThreatIntelligenceIndicator
  | where TimeGenerated >= ago(ioc_lookBack) and ExpirationDateTime > now()
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true
  //Filtering the table for Email related IOCs
  | where isnotempty(EmailSenderAddress)
  // 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 (
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated >= ago(dt_lookBack) and isnotempty(TargetUserName)
  //Normalizing the column to lower case for exact match with EmailSenderAddress column
  | extend TargetUserName = tolower(TargetUserName)
  // renaming timestamp column so it is clear the log this came from SecurityEvent table
  | extend SecurityEvent_TimeGenerated = TimeGenerated
  ),
  (WindowsEvent
  | where TimeGenerated >= ago(dt_lookBack)
  | extend TargetUserName = tostring(EventData.TargetUserName)
  | where isnotempty(TargetUserName)
  //Normalizing the column to lower case for exact match with EmailSenderAddress column
  | extend TargetUserName = tolower(TargetUserName)
  // renaming timestamp column so it is clear the log this came from SecurityEvent table
  | extend SecurityEvent_TimeGenerated = TimeGenerated
  ))
  )
  on $left.EmailSenderAddress == $right.TargetUserName
  | where SecurityEvent_TimeGenerated < ExpirationDateTime
  | summarize SecurityEvent_TimeGenerated = arg_max(SecurityEvent_TimeGenerated, *) by IndicatorId, TargetUserName
  | project SecurityEvent_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore,
  EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, Computer, EventID, TargetUserName, Activity, IpAddress, AccountType,
  LogonTypeName, LogonProcessName, Status, SubStatus
  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
  | extend timestamp = SecurityEvent_TimeGenerated  
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/EmailEntity_SecurityEvent.yaml
queryPeriod: 14d
version: 1.3.4
name: TI map Email entity to SecurityEvent
requiredDataConnectors:
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - SecurityEvents
  connectorId: WindowsSecurityEvents
- dataTypes:
  - WindowsEvent
  connectorId: WindowsForwardedEvents
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: Name
    columnName: TargetUserName
- entityType: Host
  fieldMappings:
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: IpAddress
- entityType: URL
  fieldMappings:
  - identifier: Url
    columnName: Url
id: 2fc5d810-c9cc-491a-b564-841427ae0e50
description: |
    'Identifies a match in SecurityEvent table from any Email IOC from TI'
triggerThreshold: 0

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/2fc5d810-c9cc-491a-b564-841427ae0e50')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/2fc5d810-c9cc-491a-b564-841427ae0e50')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01-preview",
      "properties": {
        "displayName": "TI map Email entity to SecurityEvent",
        "description": "'Identifies a match in SecurityEvent table from any Email IOC from TI'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "let dt_lookBack = 1h;\nlet ioc_lookBack = 14d;\nlet emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$';\nThreatIntelligenceIndicator\n| where TimeGenerated >= ago(ioc_lookBack) and ExpirationDateTime > now()\n| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId\n| where Active == true\n//Filtering the table for Email related IOCs\n| where isnotempty(EmailSenderAddress)\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(union isfuzzy=true\n(SecurityEvent\n| where TimeGenerated >= ago(dt_lookBack) and isnotempty(TargetUserName)\n//Normalizing the column to lower case for exact match with EmailSenderAddress column\n| extend TargetUserName = tolower(TargetUserName)\n// renaming timestamp column so it is clear the log this came from SecurityEvent table\n| extend SecurityEvent_TimeGenerated = TimeGenerated\n),\n(WindowsEvent\n| where TimeGenerated >= ago(dt_lookBack)\n| extend TargetUserName = tostring(EventData.TargetUserName)\n| where isnotempty(TargetUserName)\n//Normalizing the column to lower case for exact match with EmailSenderAddress column\n| extend TargetUserName = tolower(TargetUserName)\n// renaming timestamp column so it is clear the log this came from SecurityEvent table\n| extend SecurityEvent_TimeGenerated = TimeGenerated\n))\n)\non $left.EmailSenderAddress == $right.TargetUserName\n| where SecurityEvent_TimeGenerated < ExpirationDateTime\n| summarize SecurityEvent_TimeGenerated = arg_max(SecurityEvent_TimeGenerated, *) by IndicatorId, TargetUserName\n| project SecurityEvent_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore,\nEmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, Computer, EventID, TargetUserName, Activity, IpAddress, AccountType,\nLogonTypeName, LogonProcessName, Status, SubStatus\n| extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))\n| extend timestamp = SecurityEvent_TimeGenerated\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact"
        ],
        "alertRuleTemplateName": "2fc5d810-c9cc-491a-b564-841427ae0e50",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "columnName": "TargetUserName",
                "identifier": "Name"
              }
            ],
            "entityType": "Account"
          },
          {
            "fieldMappings": [
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "DnsDomain",
                "identifier": "DnsDomain"
              }
            ],
            "entityType": "Host"
          },
          {
            "fieldMappings": [
              {
                "columnName": "IpAddress",
                "identifier": "Address"
              }
            ],
            "entityType": "IP"
          },
          {
            "fieldMappings": [
              {
                "columnName": "Url",
                "identifier": "Url"
              }
            ],
            "entityType": "URL"
          }
        ],
        "templateVersion": "1.3.4",
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/EmailEntity_SecurityEvent.yaml"
      }
    }
  ]
}