TI Map Domain entity to Cloud App Events

Severity: medium
Time window: 14d
Group by: Domain, DomainName, Id, IndicatorId, ObservableValue
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: a7d2b1e4-dd9c-40fd-9651-1a136eb8f0df
name: 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:
      - ThreatIntelIndicators
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d; 
  let list_tlds =
    ThreatIntelIndicators
      | where TimeGenerated >= ago(ioc_lookBack)
      | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
      | where IsActive and (ValidUntil > now() or isempty(ValidUntil))
      //extract key part of kv pair
      | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
      | where IndicatorType == "domain-name"
      | extend DomainName = tolower(IndicatorType)
      | extend parts = split(DomainName, '.')
      | extend tld = parts[(array_length(parts) - 1)]
      | extend IndicatorId = tostring(split(Id, "--")[2])
      | summarize count() by tostring(tld)
      | summarize make_set(tld);
  let Domain_Indicators =
    ThreatIntelIndicators
      | where TimeGenerated >= ago(ioc_lookBack)
      | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
      | where IsActive and (ValidUntil > now() or isempty(ValidUntil))
      | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
      | where IndicatorType == "domain-name"
      | extend DomainName = tolower(ObservableValue)
      | extend IndicatorId = tostring(split(Id, "--")[2])
      | project-reorder *, IndicatorType, DomainName, Type;
    Domain_Indicators
      | join kind=innerunique (
    CloudAppEvents
      | extend IngestionTime = ingestion_time()
      | where IngestionTime > ago(dt_lookBack)
      | extend PAUrl = columnifexists("RequestURL", "None")
      | extend Domain = tolower(trim('"', tostring(parseurl(PAUrl).Host)))
      | extend parts = split(Domain, '.')
      | extend tld = parts[(array_length(parts) - 1)]
      | extend CloudAppEvents_TimeGenerated = TimeGenerated) on $left.DomainName == $right.Domain
      | where CloudAppEvents_TimeGenerated < ValidUntil
      | summarize CloudAppEvents_TimeGenerated = argmax(CloudAppEvents_TimeGenerated, *) by IndicatorId
      | extend 
            Description = tostring(parse_json(max_CloudAppEvents_TimeGenerated_Data).description),
            ActivityGroupNames = column_ifexists("max_CloudAppEvents_TimeGenerated_ActivityGroupNames", ""),
            ThreatType = column_ifexists("max_CloudAppEvents_TimeGenerated_ThreatType", ""),
            ExpirationDateTime = column_ifexists("max_CloudAppEvents_TimeGenerated_ExpirationDateTime", ""),
            ConfidenceScore = column_ifexists("max_CloudAppEvents_TimeGenerated_ConfidenceScore", ""),
            DomainName = column_ifexists("max_CloudAppEvents_TimeGenerated_DomainName", ""),
            ProviderName = column_ifexists("max_CloudAppEvents_TimeGenerated_IndicatorProvider", ""),
            AlertSeverity = column_ifexists("max_CloudAppEvents_TimeGenerated_ThreatSeverity", ""),
            IPAddress = column_ifexists("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: 1.0.7
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 = ThreatIntelIndicators
    | where TimeGenerated >= ago(ioc_lookBack)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
    | where IsActive and (ValidUntil > now() or isempty(ValidUntil))
    | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
    | where IndicatorType == "domain-name"
    | extend DomainName = tolower(IndicatorType)
    | extend parts = split(DomainName, '.')
    | extend tld = parts[(array_length(parts) - 1)]
    | extend IndicatorId = tostring(split(Id, "--")[2])
    | summarize count() by tostring(tld)
    | summarize make_set(tld);

Stages 1 to 9 define let Domain_Indicators (the rule's main pipeline source); stages 10 to 14 run on it.

Stage 1: `source`

ThreatIntelIndicators

Stage 2: `where`

| where TimeGenerated >= ago(ioc_lookBack)

Stage 3: `summarize`

| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue

Stage 4: `where`

| where IsActive and (ValidUntil > now() or isempty(ValidUntil))

Stage 5: `extend`

| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))

Stage 6: `where`

| where IndicatorType == "domain-name"

Stage 7: `extend`

| extend DomainName = tolower(ObservableValue)

Stage 8: `extend`

| extend IndicatorId = tostring(split(Id, "--")[2])

Stage 9: `project-reorder`

| project-reorder *, IndicatorType, DomainName, Type

Stage 10: `join`

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

Stage 11: `where`

| where CloudAppEvents_TimeGenerated < ValidUntil

Stage 12: `summarize`

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

Stage 13: `extend`

| extend 
          Description = tostring(parse_json(max_CloudAppEvents_TimeGenerated_Data).description),
          ActivityGroupNames = column_ifexists("max_CloudAppEvents_TimeGenerated_ActivityGroupNames", ""),
          ThreatType = column_ifexists("max_CloudAppEvents_TimeGenerated_ThreatType", ""),
          ExpirationDateTime = column_ifexists("max_CloudAppEvents_TimeGenerated_ExpirationDateTime", ""),
          ConfidenceScore = column_ifexists("max_CloudAppEvents_TimeGenerated_ConfidenceScore", ""),
          DomainName = column_ifexists("max_CloudAppEvents_TimeGenerated_DomainName", ""),
          ProviderName = column_ifexists("max_CloudAppEvents_TimeGenerated_IndicatorProvider", ""),
          AlertSeverity = column_ifexists("max_CloudAppEvents_TimeGenerated_ThreatSeverity", ""),
          IPAddress = column_ifexists("max_CloudAppEvents_TimeGenerated_IPAddress", "")

Stage 14: `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
`CloudAppEvents_TimeGenerated`	cross_field_compare	`ValidUntil` transforms: `op:lt`	`field:"CloudAppEvents_TimeGenerated" kind:cross_field_compare value:"ValidUntil"`
`IndicatorType`	eq	`domain-name`	`field:"IndicatorType" kind:eq value:"domain-name"`
`ValidUntil`	is_null	(no value, null check)	`field:"ValidUntil" kind:is_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`

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: extend

Stage 8: extend

Stage 9: project-reorder

Stage 10: join

Stage 11: where

Stage 12: summarize

Stage 13: extend

Stage 14: project