Preview - TI map Email entity to Cloud App Events

Back


Id	47b9bb10-d216-4359-8cef-08ca2c67e5be
Rulename	Preview - TI map Email entity to Cloud App Events
Description	Identifies compromises and attacks and detect malicious activities in one’s email entity from TI
Severity	Medium
Tactics	InitialAccess
Techniques	T1566
Required data connectors	MicrosoftDefenderThreatIntelligence MicrosoftThreatProtection
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_CloudAppEvents.yaml
Version	1.0.3
Arm template	47b9bb10-d216-4359-8cef-08ca2c67e5be.json

KQL

let dt_lookBack = 10d;
let ioc_lookBack = 30d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
ThreatIntelligenceIndicator
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now()
  | where isnotempty(EmailSenderAddress)
  | join kind=innerunique (CloudAppEvents
| extend User_Id = tostring(RawEventData.UserId)
| where isnotempty(User_Id)
| where TimeGenerated >= ago(dt_lookBack) and isnotempty(Application)
| extend CloudAppEvents_TimeGenerated = TimeGenerated 
| where User_Id matches regex emailregex) on $left.EmailSenderAddress == $right.User_Id
| where CloudAppEvents_TimeGenerated < ExpirationDateTime
| summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId, User_Id
| extend Name = tostring(split(User_Id, '@', 0)[0]), UPNSuffix = tostring(split(User_Id, '@', 1)[0])
| extend timestamp = CloudAppEvents_TimeGenerated

YAML

name: Preview - TI map Email entity to Cloud App Events
query: |
  let dt_lookBack = 10d;
  let ioc_lookBack = 30d;
  let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
  ThreatIntelligenceIndicator
    | where TimeGenerated >= ago(ioc_lookBack)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
    | where Active == true and ExpirationDateTime > now()
    | where isnotempty(EmailSenderAddress)
    | join kind=innerunique (CloudAppEvents
  | extend User_Id = tostring(RawEventData.UserId)
  | where isnotempty(User_Id)
  | where TimeGenerated >= ago(dt_lookBack) and isnotempty(Application)
  | extend CloudAppEvents_TimeGenerated = TimeGenerated 
  | where User_Id matches regex emailregex) on $left.EmailSenderAddress == $right.User_Id
  | where CloudAppEvents_TimeGenerated < ExpirationDateTime
  | summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId, User_Id
  | extend Name = tostring(split(User_Id, '@', 0)[0]), UPNSuffix = tostring(split(User_Id, '@', 1)[0])
  | extend timestamp = CloudAppEvents_TimeGenerated  
queryFrequency: 1h
triggerOperator: gt
requiredDataConnectors:
- dataTypes:
  - CloudAppEvents
  connectorId: MicrosoftThreatProtection
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: DisplayName
    columnName: Name
  - identifier: FullName
    columnName: User_Id
  - identifier: UPNSuffix
    columnName: UPNSuffix
triggerThreshold: 0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/EmailEntity_CloudAppEvents.yaml
description: |
    'Identifies compromises and attacks and detect malicious activities in one's email entity from TI'
version: 1.0.3
id: 47b9bb10-d216-4359-8cef-08ca2c67e5be
kind: Scheduled
relevantTechniques:
- T1566
severity: Medium
tactics:
- InitialAccess
queryPeriod: 14d

ARM