TI map Email entity to PaloAlto CommonSecurityLog

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
ThreatIntelligenceIndicator
//Filtering the table for Email related IOCs
| where isnotempty(EmailSenderAddress)
| where TimeGenerated >= ago(ioc_lookBack)
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
| where Active == true and ExpirationDateTime > now()
// 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 (
    CommonSecurityLog | where TimeGenerated >= ago(dt_lookBack) and isnotempty(DestinationUserID)
    // Filtering PAN Logs for specific event type to match relevant email entities
    | where DeviceVendor == "Palo Alto Networks" and  DeviceEventClassID == "wildfire" and ApplicationProtocol in ("smtp","pop3")
    | extend DestinationUserID = tolower(DestinationUserID)
    | where DestinationUserID matches regex emailregex
    | extend CommonSecurityLog_TimeGenerated = TimeGenerated
)
on $left.EmailSenderAddress == $right.DestinationUserID
| where CommonSecurityLog_TimeGenerated < ExpirationDateTime
| summarize CommonSecurityLog_TimeGenerated = arg_max(CommonSecurityLog_TimeGenerated, *) by IndicatorId, DestinationUserID
| project CommonSecurityLog_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore, EmailSenderName, EmailRecipient,
EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, DestinationUserID, DeviceEventClassID, LogSeverity, DeviceAction, SourceIP, SourcePort,
DestinationIP, DestinationPort, Protocol, ApplicationProtocol
| extend timestamp = CommonSecurityLog_TimeGenerated

description: |
    'Identifies a match in CommonSecurityLog table from any Email IOC from TI'
kind: Scheduled
tactics:
- InitialAccess
requiredDataConnectors:
- connectorId: PaloAltoNetworks
  dataTypes:
  - CommonSecurityLog
- connectorId: ThreatIntelligence
  dataTypes:
  - ThreatIntelligenceIndicator
- connectorId: ThreatIntelligenceTaxii
  dataTypes:
  - ThreatIntelligenceIndicator
- connectorId: MicrosoftDefenderThreatIntelligence
  dataTypes:
  - ThreatIntelligenceIndicator
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/EmailEntity_PaloAlto.yaml
severity: Medium
name: TI map Email entity to PaloAlto CommonSecurityLog
triggerThreshold: 0
queryPeriod: 14d
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
  ThreatIntelligenceIndicator
  //Filtering the table for Email related IOCs
  | where isnotempty(EmailSenderAddress)
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now()
  // 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 (
      CommonSecurityLog | where TimeGenerated >= ago(dt_lookBack) and isnotempty(DestinationUserID)
      // Filtering PAN Logs for specific event type to match relevant email entities
      | where DeviceVendor == "Palo Alto Networks" and  DeviceEventClassID == "wildfire" and ApplicationProtocol in ("smtp","pop3")
      | extend DestinationUserID = tolower(DestinationUserID)
      | where DestinationUserID matches regex emailregex
      | extend CommonSecurityLog_TimeGenerated = TimeGenerated
  )
  on $left.EmailSenderAddress == $right.DestinationUserID
  | where CommonSecurityLog_TimeGenerated < ExpirationDateTime
  | summarize CommonSecurityLog_TimeGenerated = arg_max(CommonSecurityLog_TimeGenerated, *) by IndicatorId, DestinationUserID
  | project CommonSecurityLog_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore, EmailSenderName, EmailRecipient,
  EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, DestinationUserID, DeviceEventClassID, LogSeverity, DeviceAction, SourceIP, SourcePort,
  DestinationIP, DestinationPort, Protocol, ApplicationProtocol
  | extend timestamp = CommonSecurityLog_TimeGenerated  
relevantTechniques:
- T1566
id: ffcd575b-3d54-482a-a6d8-d0de13b6ac63
queryFrequency: 1h
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: DestinationUserID
    identifier: Name
- entityType: IP
  fieldMappings:
  - columnName: SourceIP
    identifier: Address
- entityType: URL
  fieldMappings:
  - columnName: Url
    identifier: Url
triggerOperator: gt
version: 1.2.6