Detection rules › Kusto

TI map Domain entity to EmailUrlInfo

Severity
medium
Time window
14d
Group by
DomainName, IndicatorId, NetworkMessageId, Url, 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 Access

Telemetry coverage

Rule body

id: 87cc75df-d7b2-44f1-b064-ee924edfc879
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:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
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 = ThreatIntelligenceIndicator
    | where TimeGenerated >= ago(ioc_lookBack) // Filter threat intelligence indicators within the lookback period
    | where isnotempty(Url) // Filter for non-empty URLs
    | extend Url = tolower(Url) // Convert URLs to lowercase
    | join kind=innerunique (EmailUrlInfo_) on Url // Join with email URL info on URL
    | where Active == true and ExpirationDateTime > now() // Filter for active indicators that haven't expired
    | where EmailUrlInfo_TimeGenerated < ExpirationDateTime // Ensure email info was generated before the indicator expired
    | summarize EmailUrlInfo_TimeGenerated = arg_max(EmailUrlInfo_TimeGenerated, *) by IndicatorId, Url // Get the latest email info for each indicator
    | project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, UrlLocation, NetworkMessageId; // Select relevant columns
    let TI_Domains = ThreatIntelligenceIndicator
    | where TimeGenerated >= ago(ioc_lookBack) // Filter threat intelligence indicators within the lookback period
    | where isnotempty(DomainName) // Filter for non-empty domain names
    | extend DomainName = tolower(DomainName) // Convert domain names to lowercase
    | join kind=innerunique (EmailUrlInfo_) on $left.DomainName == $right.UrlDomain // Join with email URL info on domain name
    | where Active == true and ExpirationDateTime > now() // Filter for active indicators that haven't expired
    | where EmailUrlInfo_TimeGenerated < ExpirationDateTime // Ensure email info was generated before the indicator expired
    | summarize EmailUrlInfo_TimeGenerated = arg_max(EmailUrlInfo_TimeGenerated, *) by IndicatorId, UrlDomain // Get the latest email info for each indicator
    | project EmailUrlInfo_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, UrlDomain, UrlLocation, NetworkMessageId; // Select relevant columns
    union TI_Urls, TI_Domains // 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: 1.0.3
kind: Scheduled

Stages and Predicates

Stage 0: let

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
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;
let EmailEvents_ = EmailEvents
| where TimeGenerated >= ago(dt_lookBack);
let TI_Urls = ThreatIntelligenceIndicator <inlined as stages below>;
let TI_Domains = ThreatIntelligenceIndicator <inlined as stages below>;

Stage 1: source

let EmailUrlInfo_

Stage 2: source

let EmailEvents_

Stage 3: source

let TI_Urls

Stage 4: source

let TI_Domains

Stage 5: union

union of 2 branches

Stage 6: source

ThreatIntelligenceIndicator

Stage 7: where

where TimeGenerated >= ago(1209600s)

Stage 8: where

where isnotempty(Url)

Stage 9: extend

extend Url

Stage 10: join

join kind=innerunique (EmailUrlInfo_) on Url

Stage 11: where

where Active =~ true

Stage 12: where

where EmailUrlInfo_TimeGenerated < ExpirationDateTime

Stage 13: summarize

summarize EmailUrlInfo_TimeGenerated by IndicatorId, Url

Stage 14: project

project ActivityGroupNames, ConfidenceScore, Description, EmailUrlInfo_TimeGenerated, ExpirationDateTime, IndicatorId, NetworkMessageId, ThreatType, Url, UrlLocation

Stage 15: source

ThreatIntelligenceIndicator

Stage 16: where

where TimeGenerated >= ago(1209600s)

Stage 17: where

where isnotempty(DomainName)

Stage 18: extend

extend DomainName

Stage 19: join

join kind=innerunique (EmailUrlInfo_) on DomainName, UrlDomain

Stage 20: where

where Active =~ true

Stage 21: where

where EmailUrlInfo_TimeGenerated < ExpirationDateTime

Stage 22: summarize

summarize EmailUrlInfo_TimeGenerated by IndicatorId, UrlDomain

Stage 23: project

project ActivityGroupNames, ConfidenceScore, Description, EmailUrlInfo_TimeGenerated, ExpirationDateTime, IndicatorId, NetworkMessageId, ThreatType, UrlDomain, UrlLocation

Stage 24: extend

extend timestamp

Stage 25: join

join kind=inner (EmailEvents_) on NetworkMessageId

Stage 26: where

where not (DeliveryAction contains "Blocked")

Stage 27: extend

extend Name, UPNSuffix

Indicators

These rows show field, operator, and value matches.

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
DeliveryActionmatchBlockedexcludes:DeliveryAction field:"DeliveryAction" value:"Blocked"

Output fields

These fields are emitted when the rule matches.

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