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

Severity: medium
Time window: 14d
Group by: IndicatorId, IoC
Source: github.com/Azure/Azure-Sentinel

This rule identifies DNS requests for which response IP address is a known IoC. This analytic rule uses ASIM and supports any built-in or custom source that supports the ASIM DNS schema.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1071` Application Layer Protocol

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 22: DNSEvent (DNS query)

Rule body

id: 67775878-7f8b-4380-ac54-115e1e828901
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:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - 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:
      - ThreatIntelligenceIndicator
  - 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 = 
  ThreatIntelligenceIndicator
  | where TimeGenerated >= ago(ioc_lookBack)
  | extend IoC = coalesce(NetworkIP, NetworkDestinationIP, NetworkSourceIP,EmailSourceIpAddress,"NO_IP")
  | where IoC != "NO_IP"
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now();
  IP_TI
  | 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 < ExpirationDateTime
  | project imDns_mintime, imDns_maxtime, Description, ActivityGroupNames, IndicatorId, ThreatType, LatestIndicatorTime, ExpirationDateTime, ConfidenceScore, SrcIpAddr, IoC, Dvc, EventVendor, EventProduct, DnsQuery, DnsResponseName
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: ExpirationDateTime
  ConfidenceScore: ConfidenceScore
  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: 1.2.4
kind: Scheduled

Stages and Predicates

Parameters

let dt_lookBack = 1h;
let ioc_lookBack = 14d;

let IP_TI is inlined into the numbered stages below.

Stages 1 to 6 define let IP_TI (the rule's main pipeline source); stages 7 to 9 run on it.

Stage 1: `source`

ThreatIntelligenceIndicator

Stage 2: `where`

| where TimeGenerated >= ago(ioc_lookBack)

Stage 3: `extend`

| extend IoC = coalesce(NetworkIP, NetworkDestinationIP, NetworkSourceIP,EmailSourceIpAddress,"NO_IP")

Stage 4: `where`

| where IoC != "NO_IP"

Stage 5: `summarize`

| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId

Stage 6: `where`

| where Active == true and ExpirationDateTime > now()

Stage 7: `join`

IP_TI
| join kind=innerunique
(
_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

Stage 8: `where`

| where imDns_mintime < ExpirationDateTime

Stage 9: `project`

| project imDns_mintime, imDns_maxtime, Description, ActivityGroupNames, IndicatorId, ThreatType, LatestIndicatorTime, ExpirationDateTime, ConfidenceScore, SrcIpAddr, IoC, Dvc, EventVendor, EventProduct, DnsQuery, DnsResponseName

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Active`	eq	`true` corpus 70 (kusto 70)	`field:"Active" kind:eq value:"true"`
`DnsResponseName`	is_not_null	(no value, null check)	`field:"DnsResponseName" kind:is_not_null`
`IoC`	ne	`NO_IP`	`field:"IoC" kind:ne value:"NO_IP"`
`imDns_mintime`	cross_field_compare	`ExpirationDateTime` transforms: `op:lt`	`field:"imDns_mintime" kind:cross_field_compare value:"ExpirationDateTime"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`ActivityGroupNames`	`project`
`ConfidenceScore`	`project`
`Description`	`project`
`DnsQuery`	`project`
`DnsResponseName`	`project`
`Dvc`	`project`
`EventProduct`	`project`
`EventVendor`	`project`
`ExpirationDateTime`	`project`
`IndicatorId`	`project`
`IoC`	`project`
`LatestIndicatorTime`	`project`
`SrcIpAddr`	`project`
`ThreatType`	`project`
`imDns_maxtime`	`project`
`imDns_mintime`	`project`

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

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: extend

Stage 4: where

Stage 5: summarize

Stage 6: where

Stage 7: join

Stage 8: where

Stage 9: project