TI Map URL Entity to EmailUrlInfo

Severity: medium
Time window: 14d
Group by: Id, IndicatorId, NetworkMessageId, ObservableValue, 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: 9e32e545-e60c-47de-9941-f9ca1ada0a42
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: MicrosoftThreatProtection
    dataTypes:
      - EmailUrlInfo
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelIndicators
  - 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 EmailUrlInfo_ = materialize(EmailUrlInfo
      | where TimeGenerated >= ago(dt_lookBack)
      | 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(ThreatIntelIndicators
     //extract key part of kv pair
  | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
  | where IndicatorType == "url"
  | extend Url = ObservableValue
  | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
  | extend IndicatorId = tostring(split(Id, "--")[2])
      | where TimeGenerated >= ago(ioc_lookBack)
      | where tolower(Url) in (EmailUrls) or tolower(Url) in (EmailUrlDomains)
      | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
      | where IsActive and (ValidUntil > now() or isempty(ValidUntil)));
  (union
      (TI | join kind=innerunique (EmailUrlInfo_) on Url),
      (TI | join kind=innerunique (EmailUrlInfo_) on $left.Url == $right.UrlDomain))
  | where EmailUrlInfo_TimeGenerated < ValidUntil
  | summarize EmailUrlInfo_TimeGenerated = arg_max(EmailUrlInfo_TimeGenerated, *) by IndicatorId, Url
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, Type, ValidUntil, Confidence, 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: 1.0.5
kind: Scheduled

Stages and Predicates

Parameters

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

Let binding: `EmailUrlInfo_`

let EmailUrlInfo_ = materialize(EmailUrlInfo
    | where TimeGenerated >= ago(dt_lookBack)
    | 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.Url == $right.UrlDomain

Applied to the combined result

| where EmailUrlInfo_TimeGenerated < ValidUntil
| summarize EmailUrlInfo_TimeGenerated = arg_max(EmailUrlInfo_TimeGenerated, *) by IndicatorId, Url
| extend Description = tostring(parse_json(Data).description)
| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
| project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, Type, ValidUntil, Confidence, 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
`EmailUrlInfo_TimeGenerated`	cross_field_compare	`ValidUntil` transforms: `op:lt`	`field:"EmailUrlInfo_TimeGenerated" kind:cross_field_compare value:"ValidUntil"`
`IndicatorType`	eq	`url`	`field:"IndicatorType" kind:eq value:"url"`
`Url`	in	`EmailUrlDomains` transforms: `tolower` `EmailUrls` transforms: `tolower`	`field:"Url" kind:in`
`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`
`Confidence`	`project`
`Description`	`project`
`EmailUrlInfo_TimeGenerated`	`project`
`IndicatorId`	`project`
`NetworkMessageId`	`project`
`Type`	`project`
`Url`	`project`
`UrlDomain`	`project`
`UrlLocation`	`project`
`ValidUntil`	`project`
`timestamp`	`extend`
`Name`	`extend`
`UPNSuffix`	`extend`