TI Map URL Entity to SecurityAlert Data

id: f30a47c1-65fb-42b1-a7f4-00941c12550b
name: TI Map URL Entity to SecurityAlert Data
description: |
  'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in SecurityAlert data.'
severity: Medium
requiredDataConnectors:
  - connectorId: MicrosoftCloudAppSecurity
    dataTypes:
      - SecurityAlert
  - connectorId: AzureSecurityCenter
    dataTypes:
      - SecurityAlert
  - 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 URLRegex = "((https?|ftp|ldap|wss?|file):\\/\\/(([\\:\\%\\w\\_\\-]+(\\.|@))*((xn--)?[a-zA-Z0-9\\-]+\\.)+(xn--[a-z0-9]+|[A-Za-z]+)|\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{0,3})[.,:\\w@?^=%&\\/~+#-]*[\\w@?^=%&\\/~+#-])";
  let SecurityEvents = materialize(SecurityAlert
    | where TimeGenerated >= ago(dt_lookBack)
    | extend MSTI = case(AlertName has "TI map" and VendorName == "Microsoft" and ProductName == 'Azure Sentinel', true, false)
    | where MSTI == false
    // Extract URL from JSON data
    | mv-expand parse_json(Entities)
    | where isnotempty(Entities.Url) or isnotempty(Entities.Urls)
    | extend Url = coalesce(Entities.Url, Entities.Urls)
    | mv-expand Url
    | extend Url = tolower(Url)
    // Extract hostname from JSON data for entity mapping
    | extend Compromised_Host = tostring(parse_json(ExtendedProperties).["Compromised Host"])
    | extend Alert_TimeGenerated = TimeGenerated);
  let EventUrls = materialize(SecurityEvents | distinct Url | summarize make_list(Url));
  ThreatIntelligenceIndicator
  | where isnotempty(Url)
  | where TimeGenerated >= ago(ioc_lookBack)
  | extend Url = tolower(Url)
  | where tolower(Url) in (EventUrls)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now()
  | where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;" 
  // using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
  | join kind=innerunique (SecurityEvents) on Url
  | where Alert_TimeGenerated < ExpirationDateTime
  | summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by IndicatorId, AlertName
  | project timestamp = Alert_TimeGenerated, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, AlertName, AlertSeverity, Description, Url, Compromised_Host
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: Compromised_Host
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.2.8
kind: Scheduled