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

id: 9991c277-e0a1-4079-8c40-fbfca2705615
name: TI Map URL Entity to AuditLogs
description: |
  'This query identifies any URL indicators of compromise (IOCs) from threat intelligence (TI) by searching for matches in AuditLogs.'
severity: Medium
requiredDataConnectors:
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AuditLogs
  - 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 AuditEvents = materialize(AuditLogs
    | where TimeGenerated >= ago(dt_lookBack)
    // Extract the URL that is contained within the JSON data
    | extend Url = extract("(http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\\(\\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+)", 1,tostring(TargetResources))
    | where isnotempty(Url)
    | extend userPrincipalName = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)
    | extend TargetResourceDisplayName = tostring(TargetResources[0].displayName)
    | extend Audit_TimeGenerated = TimeGenerated);
  let AuditUrls = AuditEvents | distinct Url = tolower(Url) | summarize make_list(Url);
  ThreatIntelIndicators
  //extract key part of kv pair
       | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
       | where isnotempty(IndicatorType) and IndicatorType == "url"
       | extend Url = toupper(ObservableValue)
       | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
  | where isnotempty(Url)
  | where TimeGenerated >= ago(ioc_lookBack)
  | where tolower(Url) in (AuditUrls)
  | 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;"
  // 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 (AuditEvents) on Url
  | where Audit_TimeGenerated < ValidUntil
  | summarize Audit_TimeGenerated = arg_max(Audit_TimeGenerated, *) by Id, Url
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | project Audit_TimeGenerated, Description, ActivityGroupNames, Id, Type, ValidUntil, Confidence,
  OperationName, Identity, userPrincipalName, TargetResourceDisplayName, Url
  | extend AccountName = tostring(split(userPrincipalName, "@")[0]), AccountUPNSuffix = tostring(split(userPrincipalName, "@")[1])
  | extend HostName = tostring(split(TargetResourceDisplayName, ".")[0]), DomainIndex = toint(indexof(TargetResourceDisplayName, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(TargetResourceDisplayName, DomainIndex + 1), TargetResourceDisplayName)
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: userPrincipalName
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: AccountUPNSuffix
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: TargetResourceDisplayName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.2.8
kind: Scheduled