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Detection rules › Kusto

Infoblox - Many NXDOMAIN DNS Responses Detected

Status
available
Severity
medium
Time window
1h
Group by
SourceIP
Source
github.com/Azure/Azure-Sentinel

'Detected at least 200 DNS responses for non-existent domains in 1 hour generated by single host. Queries do not need to be the same. Customize query count, scheduling, responses and more. This rule depends on a parser based on a Kusto Function to work as expected called InfobloxCDC.'

MITRE ATT&CK coverage

TacticTechniques
ImpactT1498 Network Denial of Service, T1565 Data Manipulation

Rule body kusto

id: b2f34315-9065-488e-88d0-a171d2b0da8e
name: Infoblox - Many NXDOMAIN DNS Responses Detected
description: |
  'Detected at least 200 DNS responses for non-existent domains in 1 hour generated by single host. Queries do not need to be the same. Customize query count, scheduling, responses and more. This rule depends on a parser based on a Kusto Function to work as expected called [**InfobloxCDC**](https://aka.ms/sentinel-InfobloxCloudDataConnector-parser).'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: CefAma
    dataTypes:
      - CommonSecurityLog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Impact
relevantTechniques:
  - T1498
  - T1565
query: |
  let threshold = 200;
  InfobloxCDC
  | where DeviceEventClassID == "DNS Response"
  | where InfobloxDNSRCode == "NXDOMAIN"
  | summarize count() by SourceIP
  | where count_ > threshold
  | join kind=inner (InfobloxCDC
    | where DeviceEventClassID == "DNS Response"
    | where InfobloxDNSRCode == "NXDOMAIN"
    ) on SourceIP
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIP
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: DeviceName
      - identifier: OSVersion
        columnName: InfobloxB1SrcOSVersion
      - identifier: FullName
        columnName: SourceUserName
customDetails:
  SourceMACAddress: SourceMACAddress
eventGroupingSettings:
  aggregationKind: SingleAlert
incidentConfiguration:
  createIncident: true
version: 1.0.3
kind: Scheduled

Stages and Predicates

Parameters

let threshold = 200;

Stage 1: source

InfobloxCDC

Stage 2: where

| where DeviceEventClassID == "DNS Response"

Stage 3: where

| where InfobloxDNSRCode == "NXDOMAIN"

Stage 4: summarize

| summarize count() by SourceIP

Stage 5: where

| where count_ > threshold

Stage 6: join

| join kind=inner (InfobloxCDC
  | where DeviceEventClassID == "DNS Response"
  | where InfobloxDNSRCode == "NXDOMAIN"
  ) on SourceIP

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
DeviceEventClassIDeq
  • DNS Response transforms: cased
InfobloxDNSRCodeeq
  • NXDOMAIN transforms: cased
count_gt
  • 200 transforms: cased

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
SourceIPsummarize