TI Map URL Entity to EmailUrlInfo

Severity: medium
Time window: 14d
Group by: DomainName, IndicatorId, NetworkMessageId, Url, UrlDomain
Source: github.com/Azure/Azure-Sentinel

This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in EmailUrlInfo.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1071` Application Layer Protocol

Telemetry coverage

Platform	Record / event type
Microsoft Defender for Endpoint	`EmailEvents` action `any`: Email processed
Microsoft Defender for Endpoint	`EmailUrlInfo` action `any`: Email URL observed

Rule body

id: a0038239-72f4-4f7b-90ff-37f89f7881e0
name: TI Map URL Entity to EmailUrlInfo
description: |
  'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in EmailUrlInfo.'
severity: Medium
requiredDataConnectors:
  - connectorId: AzureActiveDirectory
    dataTypes:
      - EmailUrlInfo
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - 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 EmailUrlInfo_ = materialize(EmailUrlInfo
      | where isnotempty(Url)
      | where TimeGenerated >= ago(dt_lookBack)
      | extend Url = tolower(Url)
      | extend EmailUrlInfo_TimeGenerated = TimeGenerated);
  let EmailUrls = EmailUrlInfo_ | distinct Url | summarize make_list(Url);
  let EmailUrlDomains = EmailUrlInfo_ | distinct UrlDomain | summarize make_list(UrlDomain);
  let EmailEvents_ = materialize(EmailEvents
      | where TimeGenerated >= ago(dt_lookBack));
  let TI = materialize(ThreatIntelligenceIndicator
      | where TimeGenerated >= ago(ioc_lookBack)
      | where (isnotempty(Url) or isnotempty(DomainName)) 
      | where tolower(Url) in (EmailUrls) or tolower(DomainName) in (EmailUrlDomains)
      | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
      | where Active == true and ExpirationDateTime > now());
  (union
      (TI | join kind=innerunique (EmailUrlInfo_) on Url),
      (TI | join kind=innerunique (EmailUrlInfo_) on $left.DomainName == $right.UrlDomain))
  | where EmailUrlInfo_TimeGenerated < ExpirationDateTime
  | summarize EmailUrlInfo_TimeGenerated = arg_max(EmailUrlInfo_TimeGenerated, *) by IndicatorId, Url
  | project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, UrlDomain, UrlLocation, NetworkMessageId
  | extend timestamp = EmailUrlInfo_TimeGenerated
  | join kind=inner (EmailEvents_) on NetworkMessageId
  | where DeliveryAction !has "Blocked"
  | extend Name = tostring(split(RecipientEmailAddress, '@', 0)[0]), UPNSuffix = tostring(split(RecipientEmailAddress, '@', 1)[0])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: RecipientEmailAddress
      - identifier: Name
        columnName: Name
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.0.2
kind: Scheduled

Stages and Predicates

Parameters

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

Let binding: `EmailUrlInfo_`

let EmailUrlInfo_ = materialize(EmailUrlInfo
    | where isnotempty(Url)
    | where TimeGenerated >= ago(dt_lookBack)
    | extend Url = tolower(Url)
    | extend EmailUrlInfo_TimeGenerated = TimeGenerated);

Let binding: `EmailUrls`

let EmailUrls = EmailUrlInfo_ | distinct Url | summarize make_list(Url);

Let binding: `EmailUrlDomains`

let EmailUrlDomains = EmailUrlInfo_ | distinct UrlDomain | summarize make_list(UrlDomain);

Let binding: `EmailEvents_`

let EmailEvents_ = materialize(EmailEvents
    | where TimeGenerated >= ago(dt_lookBack));

union (2 sources)

Each leg below queries one source; the rule matches if any leg does. Sources: TI, TI

Leg 1: `TI`

TI | join kind=innerunique (EmailUrlInfo_) on Url

Leg 2: `TI`

TI | join kind=innerunique (EmailUrlInfo_) on $left.DomainName == $right.UrlDomain

Applied to the combined result

| where EmailUrlInfo_TimeGenerated < ExpirationDateTime
| summarize EmailUrlInfo_TimeGenerated = arg_max(EmailUrlInfo_TimeGenerated, *) by IndicatorId, Url
| project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, UrlDomain, UrlLocation, NetworkMessageId
| extend timestamp = EmailUrlInfo_TimeGenerated
| join kind=inner (EmailEvents_) on NetworkMessageId
| where DeliveryAction !has "Blocked"
| extend Name = tostring(split(RecipientEmailAddress, '@', 0)[0]), UPNSuffix = tostring(split(RecipientEmailAddress, '@', 1)[0])

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`DeliveryAction`	match	`Blocked`	`excludes:DeliveryAction` `field:"DeliveryAction" value:"Blocked"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Active`	eq	`true`	`field:"Active" kind:eq value:"true"`
`DomainName`	in	`EmailUrlDomains` transforms: `tolower`	`field:"DomainName" kind:in value:"EmailUrlDomains"`
`DomainName`	is_not_null	(no value, null check)	`field:"DomainName" kind:is_not_null`
`EmailUrlInfo_TimeGenerated`	cross_field_compare	`ExpirationDateTime` transforms: `op:lt`	`field:"EmailUrlInfo_TimeGenerated" kind:cross_field_compare value:"ExpirationDateTime"`
`Url`	in	`EmailUrls` transforms: `tolower`	`field:"Url" kind:in value:"EmailUrls"`
`Url`	is_not_null	(no value, null check)	`field:"Url" kind:is_not_null`

Output fields

These fields are emitted when the rule matches.

Field	Source
`ActivityGroupNames`	`project`
`ConfidenceScore`	`project`
`Description`	`project`
`EmailUrlInfo_TimeGenerated`	`project`
`ExpirationDateTime`	`project`
`IndicatorId`	`project`
`NetworkMessageId`	`project`
`ThreatType`	`project`
`Url`	`project`
`UrlDomain`	`project`
`UrlLocation`	`project`
`timestamp`	`extend`
`Name`	`extend`
`UPNSuffix`	`extend`