Detection rules › Kusto

TI Map URL Entity to UrlClickEvents

Severity
medium
Time window
14d
Group by
Id, ObservableValue, TI_Url, Url, UrlChain
Source
github.com/Azure/Azure-Sentinel

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

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1071 Application Layer Protocol

Rule body kusto

id: ad4fa1f2-2189-459c-9458-f77d2039d2f5
name: TI Map URL Entity to UrlClickEvents
description: |
  'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in UrlClickEvents.'
severity: Medium
requiredDataConnectors:
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - UrlClickEvents
  - 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 UrlClickEvents_ = materialize(UrlClickEvents
      | where TimeGenerated >= ago(dt_lookBack)
      | extend UrlClickEvents_TimeGenerated = TimeGenerated);
  let ChainReportID = UrlClickEvents_
      | mv-expand todynamic(UrlChain)
      | extend UrlChain = tolower(UrlChain)
      | project ReportId, Url, UrlChain;
  // Url is not always in UrlChain, so we need to check both
  let ClickedUrls = 
    (union isfuzzy=false (ChainReportID), (ChainReportID | project Url = UrlChain))
    | distinct Url
    | summarize make_list(Url);
  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)
    | where TimeGenerated >= ago(ioc_lookBack)
    | where tolower(Url) in (ClickedUrls)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
    | where IsActive and (ValidUntil > now() or isempty(ValidUntil))
    | project-rename TI_Url = Url, TI_Type = Type
    );
  (union isfuzzy=false (TI | join kind=innerunique (ChainReportID) on $left.TI_Url == $right.UrlChain),
    (TI | join kind=innerunique (ChainReportID) on $left.TI_Url == $right.Url))
  | project-away UrlChain
  | join kind=innerunique (UrlClickEvents_) on ReportId
  | where UrlClickEvents_TimeGenerated < ValidUntil
  | summarize UrlClickEvents_TimeGenerated = arg_max(UrlClickEvents_TimeGenerated, *) by Id
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | project UrlClickEvents_TimeGenerated, AccountUpn, Description, ActivityGroupNames, Id, Type, ValidUntil, Confidence, Url, NetworkMessageId
  | extend timestamp = UrlClickEvents_TimeGenerated
  | extend timestamp = UrlClickEvents_TimeGenerated, Name = tostring(split(AccountUpn, '@', 0)), UPNSuffix = tostring(split(AccountUpn, '@', 1))
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: AccountUpn
      - 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: UrlClickEvents_

let UrlClickEvents_ = materialize(UrlClickEvents
    | where TimeGenerated >= ago(dt_lookBack)
    | extend UrlClickEvents_TimeGenerated = TimeGenerated);

Derived from dt_lookBack.

Let binding: ChainReportID

let ChainReportID = UrlClickEvents_
    | mv-expand todynamic(UrlChain)
    | extend UrlChain = tolower(UrlChain)
    | project ReportId, Url, UrlChain;

Derived from UrlClickEvents_.

Let binding: ClickedUrls

let ClickedUrls = (union isfuzzy=false (ChainReportID), (ChainReportID | project Url = UrlChain))
  | distinct Url
  | summarize make_list(Url);

Derived from ChainReportID.

Let binding: TI

let TI = materialize(ThreatIntelIndicators
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
| where IndicatorType == "url"
| extend Url = ObservableValue
  | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
  | where TimeGenerated >= ago(ioc_lookBack)
  | where tolower(Url) in (ClickedUrls)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
  | where IsActive and (ValidUntil > now() or isempty(ValidUntil))
  | project-rename TI_Url = Url, TI_Type = Type
  );

Derived from ioc_lookBack, ClickedUrls.

union isfuzzy=false (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 (ChainReportID) on $left.TI_Url == $right.UrlChain

Leg 2: TI

TI | join kind=innerunique (ChainReportID) on $left.TI_Url == $right.Url

Applied to the combined result

| project-away UrlChain
| join kind=innerunique (UrlClickEvents_) on ReportId
| where UrlClickEvents_TimeGenerated < ValidUntil
| summarize UrlClickEvents_TimeGenerated = arg_max(UrlClickEvents_TimeGenerated, *) by Id
| extend Description = tostring(parse_json(Data).description)
| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
| project UrlClickEvents_TimeGenerated, AccountUpn, Description, ActivityGroupNames, Id, Type, ValidUntil, Confidence, Url, NetworkMessageId
| extend timestamp = UrlClickEvents_TimeGenerated
| extend timestamp = UrlClickEvents_TimeGenerated, Name = tostring(split(AccountUpn, '@', 0)), UPNSuffix = tostring(split(AccountUpn, '@', 1))

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 corpus 11 (kusto 11)
Urlin
  • ClickedUrls transforms: tolower, cased corpus 2 (kusto 2)
UrlClickEvents_TimeGeneratedlt
  • ValidUntil transforms: cased
ValidUntilis_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
AccountUpnproject
ActivityGroupNamesproject
Confidenceproject
Descriptionproject
Idproject
NetworkMessageIdproject
Typeproject
Urlproject
UrlClickEvents_TimeGeneratedproject
ValidUntilproject
timestampextend
Nameextend
UPNSuffixextend