TI Map IP entity to DNS Events (ASIM DNS schema)

id: b306fba8-1a28-449f-aa24-30362e16d4f5
name: TI Map IP entity to DNS Events (ASIM DNS schema)
description: |
  'This rule identifies DNS requests for which response IP address is a known IoC. This analytic rule uses [ASIM](https://aka.ms/AboutASIM) and supports any built-in or custom source that supports the ASIM DNS schema.'
severity: Medium
requiredDataConnectors:
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: DNS
    dataTypes:
      - DnsEvents
  - connectorId: AzureFirewall
    dataTypes: 
      - AzureDiagnostics
  - connectorId: Zscaler
    dataTypes:
      - CommonSecurityLog
  - connectorId: InfobloxNIOS
    dataTypes: 
      - Syslog
  - connectorId: GCPDNSDataConnector
    dataTypes: 
      - GCP_DNS_CL
  - connectorId: NXLogDnsLogs
    dataTypes: 
      - NXLog_DNS_Server_CL
  - connectorId: CiscoUmbrellaDataConnector
    dataTypes: 
      - Cisco_Umbrella_dns_CL
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: Corelight
    dataTypes: 
      - Corelight_CL
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
tags:
  - ParentAlert: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ThreatIntelligenceIndicator/IPEntity_DnsEvents.yaml
    version: 1.0.0
  - Schema: ASIMDns
    SchemaVersion: 0.1.1
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let IP_TI = 
  ThreatIntelIndicators
  | where TimeGenerated >= ago(ioc_lookBack)
  //extract key part of kv pair
  | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
  | where IndicatorType == "ipv4-addr"
  | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
  | extend NetworkSourceIP = ObservableValue
  | extend IoC = NetworkSourceIP
  | extend IndicatorId = tostring(split(Id, "--")[2])
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
  | where IsActive and (ValidUntil > now() or isempty(ValidUntil));
  IP_TI
   | project-reorder *, IsActive, Tags, TrafficLightProtocolLevel, NetworkSourceIP, Type, IoC
  | join kind=innerunique // 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
  (
  _Im_Dns(starttime=ago(dt_lookBack))
  | where isnotempty(DnsResponseName)
  | summarize imDns_mintime=min(TimeGenerated), imDns_maxtime=max(TimeGenerated) by SrcIpAddr, DnsQuery, DnsResponseName, Dvc, EventProduct, EventVendor
  | extend addresses = extract_all (@'(\d+\.\d+\.\d+\.\d+)', DnsResponseName)
  | mv-expand IoC = addresses to typeof(string)
  )
  on IoC
  | where imDns_mintime < ValidUntil
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | extend ThreatType = tostring(Data.indicator_types[0])
  | project imDns_mintime, imDns_maxtime, Description, ActivityGroupNames, IndicatorId, ThreatType, LatestIndicatorTime, ValidUntil, Confidence, 
  SrcIpAddr, IoC, Dvc, EventVendor, EventProduct, DnsQuery, DnsResponseName, Type
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Dvc
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IoC
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SrcIpAddr
customDetails:
  LatestIndicatorTime: LatestIndicatorTime
  Description: Description
  ActivityGroupNames: ActivityGroupNames
  IndicatorId: IndicatorId
  ThreatType: ThreatType
  ExpirationDateTime: ValidUntil
  ConfidenceScore: Confidence
  DNSRequestTime: imDns_mintime
  SourceIPAddress: SrcIpAddr
  DnsQuery: DnsQuery
alertDetailsOverride:
  alertDisplayNameFormat: The response {{IoC}} to DNS query matched an IoC 
  alertDescriptionFormat: The response address {{IoC}} to a DNS query matched a known indicator of compromise of {{ThreatType}}. Consult the threat intelligence blade for more information on the indicator.
version: 1.2.11
kind: Scheduled