Preview - TI map Domain entity to Cloud App Events

Severity: medium
Time window: 14d
Group by: Domain, IndicatorId, TI_DomainEntity
Source: github.com/Azure/Azure-Sentinel

Identifies compromises and attacks and detect malicious activities in one's domain entity from TI.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1071` Application Layer Protocol

Telemetry coverage

Platform	Record / event type
Microsoft Defender for Endpoint	`CloudAppEvents` action `any`: Cloud app activity

Rule body

id: b97e118c-b7fa-42a6-84de-2e13443fbb8f
name: Preview - TI map Domain entity to Cloud App Events
description: |
    'Identifies compromises and attacks and detect malicious activities in one's domain entity from TI.'
severity: Medium
requiredDataConnectors:
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - CloudAppEvents
  - 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 list_tlds =
    ThreatIntelligenceIndicator
      | where TimeGenerated >= ago(ioc_lookBack)
      | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
      | where Active == true and ExpirationDateTime > now()
      | where isnotempty(DomainName)
      | extend DomainName = tolower(DomainName)
      | extend parts = split(DomainName, '.')
      | extend tld = parts[(array_length(parts) - 1)]
      | summarize count() by tostring(tld)
      | summarize make_set(tld);
  let Domain_Indicators =
    ThreatIntelligenceIndicator
      | where TimeGenerated >= ago(ioc_lookBack)
      | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
      | where Active == true and ExpirationDateTime > now()
      | extend TI_DomainEntity = DomainName
      | where isnotempty(TI_DomainEntity);
    Domain_Indicators
      | join kind=innerunique (
    CloudAppEvents
      | extend IngestionTime = ingestion_time()
      | where IngestionTime > ago(dt_lookBack)
      | extend PAUrl = columnifexists("RequestURL", "None")
      | extend Domain = trim('"', tostring(parseurl(PAUrl).Host))
      | extend Domain = tolower(Domain)
      | extend parts = split(Domain, '.')
      | extend tld = parts[(array_length(parts) - 1)]
      | extend CloudAppEvents_TimeGenerated = TimeGenerated) on $left.TI_DomainEntity == $right.Domain
      | where CloudAppEvents_TimeGenerated < ExpirationDateTime
      | summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId
      | extend Description = max_CloudAppEvents_TimeGenerated_Description, ActivityGroupNames = max_CloudAppEvents_TimeGenerated_ActivityGroupNames, ThreatType = max_CloudAppEvents_TimeGenerated_ThreatType, ExpirationDateTime = max_CloudAppEvents_TimeGenerated_ExpirationDateTime, ConfidenceScore = max_CloudAppEvents_TimeGenerated_ConfidenceScore, DomainName = max_CloudAppEvents_TimeGenerated_DomainName, ProviderName = max_CloudAppEvents_TimeGenerated_IndicatorProvider, AlertSeverity = max_CloudAppEvents_TimeGenerated_ThreatSeverity, IPAddress = max_CloudAppEvents_TimeGenerated_IPAddress
      | project CloudAppEvents_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, DomainName, ProviderName, AlertSeverity, IPAddress
entityMappings:
  - entityType: DNS
    fieldMappings:
      - identifier: DomainName
        columnName: DomainName
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IPAddress
version: 1.0.3
kind: Scheduled

Stages and Predicates

Parameters

let dt_lookBack = 1h;
let ioc_lookBack = 14d;

let Domain_Indicators is inlined into the numbered stages below.

Let binding: `list_tlds`

let list_tlds = ThreatIntelligenceIndicator
    | where TimeGenerated >= ago(ioc_lookBack)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
    | where Active == true and ExpirationDateTime > now()
    | where isnotempty(DomainName)
    | extend DomainName = tolower(DomainName)
    | extend parts = split(DomainName, '.')
    | extend tld = parts[(array_length(parts) - 1)]
    | summarize count() by tostring(tld)
    | summarize make_set(tld);

Stages 1 to 6 define let Domain_Indicators (the rule's main pipeline source); stages 7 to 11 run on it.

Stage 1: `source`

ThreatIntelligenceIndicator

Stage 2: `where`

| where TimeGenerated >= ago(ioc_lookBack)

Stage 3: `summarize`

| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId

Stage 4: `where`

| where Active == true and ExpirationDateTime > now()

Stage 5: `extend`

| extend TI_DomainEntity = DomainName

Stage 6: `where`

| where isnotempty(TI_DomainEntity)

Stage 7: `join`

Domain_Indicators
| join kind=innerunique (
  CloudAppEvents
    | extend IngestionTime = ingestion_time()
    | where IngestionTime > ago(dt_lookBack)
    | extend PAUrl = columnifexists("RequestURL", "None")
    | extend Domain = trim('"', tostring(parseurl(PAUrl).Host))
    | extend Domain = tolower(Domain)
    | extend parts = split(Domain, '.')
    | extend tld = parts[(array_length(parts) - 1)]
    | extend CloudAppEvents_TimeGenerated = TimeGenerated) on $left.TI_DomainEntity == $right.Domain

Stage 8: `where`

| where CloudAppEvents_TimeGenerated < ExpirationDateTime

Stage 9: `summarize`

| summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId

Stage 10: `extend`

| extend Description = max_CloudAppEvents_TimeGenerated_Description, ActivityGroupNames = max_CloudAppEvents_TimeGenerated_ActivityGroupNames, ThreatType = max_CloudAppEvents_TimeGenerated_ThreatType, ExpirationDateTime = max_CloudAppEvents_TimeGenerated_ExpirationDateTime, ConfidenceScore = max_CloudAppEvents_TimeGenerated_ConfidenceScore, DomainName = max_CloudAppEvents_TimeGenerated_DomainName, ProviderName = max_CloudAppEvents_TimeGenerated_IndicatorProvider, AlertSeverity = max_CloudAppEvents_TimeGenerated_ThreatSeverity, IPAddress = max_CloudAppEvents_TimeGenerated_IPAddress

Stage 11: `project`

| project CloudAppEvents_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, DomainName, ProviderName, AlertSeverity, IPAddress

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Active`	eq	`true`	`field:"Active" kind:eq value:"true"`
`CloudAppEvents_TimeGenerated`	cross_field_compare	`ExpirationDateTime` transforms: `op:lt`	`field:"CloudAppEvents_TimeGenerated" kind:cross_field_compare value:"ExpirationDateTime"`
`TI_DomainEntity`	is_not_null	(no value, null check)	`field:"TI_DomainEntity" kind:is_not_null`

Output fields

These fields are emitted when the rule matches.

Field	Source
`ActivityGroupNames`	`project`
`AlertSeverity`	`project`
`CloudAppEvents_TimeGenerated`	`project`
`ConfidenceScore`	`project`
`Description`	`project`
`DomainName`	`project`
`ExpirationDateTime`	`project`
`IPAddress`	`project`
`IndicatorId`	`project`
`ProviderName`	`project`
`ThreatType`	`project`

Preview - TI map Domain entity to Cloud App Events

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Parameters

Let binding: list_tlds

Stage 1: source

Stage 2: where

Stage 3: summarize

Stage 4: where

Stage 5: extend

Stage 6: where

Stage 7: join

Stage 8: where

Stage 9: summarize

Stage 10: extend

Stage 11: project