Solutions/Threat Intelligence (NEW)/Analytic Rules/DomainEntity_SecurityAlert.yaml

id: df88b403-1cb9-49ea-a43d-b6613051cf7f
name: TI map Domain entity to SecurityAlert
description: |
  'Identifies a match in SecurityAlert table from any Domain IOC from TI'
severity: Medium
requiredDataConnectors:
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: MicrosoftCloudAppSecurity
    dataTypes:
      - SecurityAlert
  - connectorId: AzureSecurityCenter
    dataTypes:
      - SecurityAlert
  - 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 SecurityAlerts = SecurityAlert
  | where TimeGenerated > ago(dt_lookBack)
  | extend domain = todynamic(dynamic_to_json(extract_all(@"(((xn--)?[a-z0-9\-]+\.)+([a-z]+|(xn--[a-z0-9]+)))", dynamic([1]), tolower(Entities))))
  | where isnotempty(domain)
  | mv-expand domain
  | extend domain = tostring(domain)
  | extend EntitiesDynamicArray = parse_json(Entities)
  | mv-apply EntitiesDynamicArray on
      (summarize
          HostName = take_anyif(tostring(EntitiesDynamicArray.HostName), EntitiesDynamicArray.Type == "host"),
          IP_addr = take_anyif(tostring(EntitiesDynamicArray.Address), EntitiesDynamicArray.Type == "ip")
      )
  | extend Alert_TimeGenerated = TimeGenerated
  | extend Alert_Description = Description;
  let AlertDomains = SecurityAlerts
  | distinct domain
  | summarize make_list(domain);
  let Domain_Indicators = materialize(ThreatIntelIndicators
  | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
  | where isnotempty(IndicatorType) and IndicatorType == "domain-name"
  | extend DomainName = tolower(ObservableValue)
  | where isnotempty(DomainName)
  | where TimeGenerated >= ago(ioc_lookBack)
  | extend TI_DomainEntity = tolower(DomainName)
  | where TI_DomainEntity in (AlertDomains)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
  | where IsActive == true and ValidUntil > now()
  | extend Description = tostring(parse_json(Data).description)
  | where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;");
  Domain_Indicators
  // Using innerunique to keep performance fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
  | join kind=innerunique (SecurityAlerts) on $left.TI_DomainEntity == $right.domain
  | where Alert_TimeGenerated < ValidUntil
  | summarize Alert_TimeGenerated = arg_max(Alert_TimeGenerated, *) by Id, AlertName
  | extend ActivityGroupNames = extract("ActivityGroup:([^,]+)", 1, tostring(parse_json(Data).labels))
  | extend Url = DomainName
  | project Alert_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, ConfidenceScore, DomainName, AlertName, Alert_Description, ProviderName, AlertSeverity, ConfidenceLevel, HostName, IP_addr, Url, Entities, Type, TI_DomainEntity
  | extend timestamp = Alert_TimeGenerated
  | project-reorder *, ConfidenceScore, DomainName, AlertName, Alert_TimeGenerated, ProviderName, AlertSeverity, Entities, Type, TI_DomainEntity, timestamp
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: HostName
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IP_addr
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.4.3
kind: Scheduled