Detection rules › Kusto

TI map Domain entity to EmailUrlInfo

Severity
medium
Time window
14d
Group by
DomainName, Id, ObservableValue, UrlDomain
Source
github.com/Azure/Azure-Sentinel

'Identifies a match in EmailUrlInfo table from any Domain IOC from TI.'

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1566 Phishing

Rule body kusto

id: b56e2290-c65b-45a5-9636-3651e85bbe5d
name: TI map Domain entity to EmailUrlInfo
description: |
  'Identifies a match in EmailUrlInfo table from any Domain IOC from TI.'
severity: Medium
requiredDataConnectors:
  - connectorId: Office365
    dataTypes:
      - EmailUrlInfo
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1566
query: |
    let dt_lookBack = 1h; // Define the lookback period for email data as 1 hour
    let ioc_lookBack = 14d; // Define the lookback period for threat intelligence data as 14 days
    let EmailUrlInfo_ = EmailUrlInfo| where isnotempty(Url) or isnotempty(UrlDomain) // Filter for non-empty URLs or URL domains
    | where TimeGenerated >= ago(dt_lookBack) // Filter for records within the lookback period
    | extend Url = tolower(Url), UrlDomain = tolower(UrlDomain) // Convert URLs and domains to lowercase
    | extend EmailUrlInfo_TimeGenerated = TimeGenerated; // Create a new column for the time generated
    let EmailEvents_ = EmailEvents
    | where TimeGenerated >= ago(dt_lookBack); // Filter email events within the lookback period
    let TI_Urls = ThreatIntelIndicators
    | where TimeGenerated >= ago(ioc_lookBack) // Filter threat intelligence indicators within the lookback period
    | summarize arg_max(TimeGenerated, *) by Id, ObservableValue // Get latest record per Id FIRST
    | where IsActive == true and ValidUntil > now() // THEN filter for active indicators that haven't expired
    | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
    | where isnotempty(IndicatorType) and IndicatorType == "url"
    | extend Url = tolower(ObservableValue)
    | where isnotempty(Url) // Filter for non-empty URLs
    | join kind=innerunique (EmailUrlInfo_) on Url // Join with email URL info on URL
    | extend Description = tostring(parse_json(Data).description)
    | extend ActivityGroupNames = extract("ActivityGroup:([^,]+)", 1, tostring(parse_json(Data).labels))
    | project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, Url, UrlLocation, NetworkMessageId; // Select relevant columns
    let TI_Domains = ThreatIntelIndicators
    | where TimeGenerated >= ago(ioc_lookBack) // Filter threat intelligence indicators within the lookback period
    | where isnotempty(ObservableValue) // Filter for non-empty domain names
    | extend DomainName = tolower(ObservableValue) // Convert domain names to lowercase
    | where ObservableKey == "domain-name:value"
    | summarize arg_max(TimeGenerated, *) by Id, ObservableValue // Get latest record per Id FIRST
    | where IsActive == true // THEN filter for active indicators
    | extend TrafficLightProtocolLevel = AdditionalFields.TLPLevel
    | extend IndicatorId = tostring(split(Id, "--")[2]);
    let TI_Domains_UrlInfo = TI_Domains
    | project-reorder *, IsActive, Tags, TrafficLightProtocolLevel, DomainName, Type
    | join kind=innerunique (EmailUrlInfo_) on $left.DomainName == $right.UrlDomain // Join with email URL info on domain name
    | extend ExpirationDateTime = ValidUntil
    | extend Description = Data.description
    | extend ThreatType =  Data.type
    | extend ConfidenceScore = Confidence
    | extend ActivityGroupNames = replace_string(tostring(parse_json(tostring(Data.labels))[0]),"ActivityGroup:","")
    | where ExpirationDateTime > now() // Filter for indicators that haven't expired
    | project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, UrlDomain, UrlLocation, NetworkMessageId; // Select relevant columns
    union TI_Urls, TI_Domains_UrlInfo // Combine URL and domain threat intelligence data
    | extend timestamp = EmailUrlInfo_TimeGenerated // Add a timestamp column
    | join kind=inner (EmailEvents_) on NetworkMessageId // Join with email events on network message ID
    | where DeliveryAction !has "Blocked" // Filter out blocked delivery actions
    | extend Name = tostring(split(RecipientEmailAddress, '@', 0)[0]), UPNSuffix = tostring(split(RecipientEmailAddress, '@', 1)[0]); // Extract name and UPN suffix from recipient email address"
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: RecipientEmailAddress
      - identifier: Name
        columnName: Name
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.0.6
kind: Scheduled

Stages and Predicates

Parameters

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

Let binding: EmailUrlInfo_

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

Derived from dt_lookBack.

Let binding: EmailEvents_

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

Derived from dt_lookBack.

Let binding: TI_Urls

let TI_Urls = ThreatIntelIndicators
| where TimeGenerated >= ago(ioc_lookBack)
| summarize arg_max(TimeGenerated, *) by Id, ObservableValue
| where IsActive == true and ValidUntil > now()
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
| where isnotempty(IndicatorType) and IndicatorType == "url"
| extend Url = tolower(ObservableValue)
| where isnotempty(Url)
| join kind=innerunique (EmailUrlInfo_) on Url
| extend Description = tostring(parse_json(Data).description)
| extend ActivityGroupNames = extract("ActivityGroup:([^,]+)", 1, tostring(parse_json(Data).labels))
| project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, Url, UrlLocation, NetworkMessageId;

Derived from ioc_lookBack, EmailUrlInfo_.

Let binding: TI_Domains

let TI_Domains = ThreatIntelIndicators
| where TimeGenerated >= ago(ioc_lookBack)
| where isnotempty(ObservableValue)
| extend DomainName = tolower(ObservableValue)
| where ObservableKey == "domain-name:value"
| summarize arg_max(TimeGenerated, *) by Id, ObservableValue
| where IsActive == true
| extend TrafficLightProtocolLevel = AdditionalFields.TLPLevel
| extend IndicatorId = tostring(split(Id, "--")[2]);

Derived from ioc_lookBack.

Let binding: TI_Domains_UrlInfo

let TI_Domains_UrlInfo = TI_Domains
| project-reorder *, IsActive, Tags, TrafficLightProtocolLevel, DomainName, Type
| join kind=innerunique (EmailUrlInfo_) on $left.DomainName == $right.UrlDomain
| extend ExpirationDateTime = ValidUntil
| extend Description = Data.description
| extend ThreatType =  Data.type
| extend ConfidenceScore = Confidence
| extend ActivityGroupNames = replace_string(tostring(parse_json(tostring(Data.labels))[0]),"ActivityGroup:","")
| where ExpirationDateTime > now()
| project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, UrlDomain, UrlLocation, NetworkMessageId;

Derived from EmailUrlInfo_, TI_Domains.

union (2 sources)

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

Leg 1: TI_Urls

Leg 2: TI_Domains_UrlInfo

Applied to the combined result

| 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

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
DeliveryActionmatchBlocked

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
IndicatorTypeeq
  • url transforms: cased
IndicatorTypeis_not_null
  • (no value, null check)
IsActiveeq
  • true transforms: cased
ObservableKeyeq
  • domain-name:value transforms: cased
ObservableValueis_not_null
  • (no value, null check)
Urlis_not_null
  • (no value, null check)
UrlDomainis_not_null
  • (no value, null check)

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
ActivityGroupNamesproject
ConfidenceScoreproject
Descriptionproject
EmailUrlInfo_TimeGeneratedproject
ExpirationDateTimeproject
IndicatorIdproject
NetworkMessageIdproject
ThreatTypeproject
UrlDomainproject
UrlLocationproject
timestampextend
Nameextend
UPNSuffixextend