ThreatConnect TI map Email entity to SigninLogs

id: ecb68ce7-c309-59a7-a8de-07ccf2a0ea4f
name: ThreatConnect TI map Email entity to SigninLogs
version: 1.2.5
kind: Scheduled
description: |
  'Identifies a match in SigninLogs table from any Email IOC from ThreatConnect TI'
severity: Medium
requiredDataConnectors:
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: AzureActiveDirectory
    dataTypes:
      - SigninLogs
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AADNonInteractiveUserSignInLogs
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
  let aadFunc = (tableName:string){
  ThreatIntelligenceIndicator
    | where TimeGenerated >= ago(ioc_lookBack)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
    | where ExpirationDateTime > now() and Active == true
  // Filter out non ThreatConnect TI Sources
  | where SourceSystem startswith "ThreatConnect-"
  //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 (
      table(tableName) | where TimeGenerated >= ago(dt_lookBack) and isnotempty(UserPrincipalName)
      //Normalizing the column to lower case for exact match with EmailSenderAddress column
      | extend UserPrincipalName = tolower(UserPrincipalName)
      | where UserPrincipalName matches regex emailregex
      | extend Status = todynamic(DeviceDetail), LocationDetails = todynamic(LocationDetails)
      | extend StatusCode = tostring(Status.errorCode), StatusDetails = tostring(Status.additionalDetails)
      | extend State = tostring(LocationDetails.state), City = tostring(LocationDetails.city), Region = tostring(LocationDetails.countryOrRegion)
      // renaming timestamp column so it is clear the log this came from SigninLogs table
      | extend SigninLogs_TimeGenerated = TimeGenerated, Type = Type
  )
  on $left.EmailSenderAddress == $right.UserPrincipalName
  | where SigninLogs_TimeGenerated < ExpirationDateTime
  | summarize SigninLogs_TimeGenerated = arg_max(SigninLogs_TimeGenerated, *) by IndicatorId, UserPrincipalName
  | project SigninLogs_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore,
  EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, IPAddress, UserPrincipalName, AppDisplayName,
  StatusCode, StatusDetails, NetworkIP, NetworkDestinationIP, NetworkSourceIP, Type
  | extend Name = tostring(split(UserPrincipalName, '@', 0)[0]), UPNSuffix = tostring(split(UserPrincipalName, '@', 1)[0])
  | extend timestamp = SigninLogs_TimeGenerated
  };
  let aadSignin = aadFunc("SigninLogs");
  let aadNonInt = aadFunc("AADNonInteractiveUserSignInLogs");
  union isfuzzy=true aadSignin, aadNonInt
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: Name
      - identifier: UPNSuffix
        columnName: UPNSuffix 
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IPAddress
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url