detection.wiki

Detection rules › Kusto

Certified Pre-Owned - backup of CA private key - rule 2

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

This query identifies someone that performs a backup of they CA key.

MITRE ATT&CK coverage

TacticTechniques
StealthT1036 Masquerading

Event coverage

ProviderEventTitle
Security-AuditingEvent ID 5059Key migration operation.

Rule body kusto

id: 88f8fbc0-345d-458e-85f6-f73921d5ef50
name: Certified Pre-Owned - backup of CA private key - rule 2
description: |
  This query identifies someone that performs a backup of they CA key.
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - DefenseEvasion
relevantTechniques:
  - T1036
query: |
  SecurityEvent
  // Fill in the machine name of your CA.
  | where EventID == 5059 and Computer contains "<YOUR CA MACHINE NAME>"
  | where EventData contains "%%2499" and EventData contains "%%2464"
  | extend EventData=parse_xml(EventData)
  | mv-apply d=EventData.EventData.Data on
  (
      where d["@Name"]=="KeyName"
      | project KeyName=tostring(d["#text"])
  )
  | mv-apply d=EventData.EventData.Data on
  (
      where d["@Name"]=="SubjectUserName"
      | project SubjectUserName=tostring(d["#text"])
  )
  | parse Account with "<YOUR DOMAIN NAME>\\" CleanAccount "$"
  | where not(Computer startswith CleanAccount)
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
version: 1.0.1
kind: Scheduled

Stages and Predicates

Stage 1: source

SecurityEvent

Stage 2: where

| where EventID == 5059 and Computer contains "<YOUR CA MACHINE NAME>"

Stage 3: where

| where EventData contains "%%2499" and EventData contains "%%2464"

Stage 4: extend

| extend EventData=parse_xml(EventData)

Stage 5: kusto:mv-apply

| mv-apply d=EventData.EventData.Data on
(
    where d["@Name"]=="KeyName"
    | project KeyName=tostring(d["#text"])
)

Stage 6: kusto:mv-apply

| mv-apply d=EventData.EventData.Data on
(
    where d["@Name"]=="SubjectUserName"
    | project SubjectUserName=tostring(d["#text"])
)

Stage 7: parse

| parse Account with "<YOUR DOMAIN NAME>\\" CleanAccount "$"

Stage 8: where

| where not(Computer startswith CleanAccount)

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
Computerstarts_withCleanAccount

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
@Nameeq
  • KeyName transforms: cased corpus 2 (kusto 2)
  • SubjectUserName transforms: cased corpus 2 (kusto 2)
Computercontains
  • <YOUR CA MACHINE NAME> corpus 2 (kusto 2)
EventDatacontains
  • %%2464
  • %%2499 corpus 2 (kusto 2)
EventIDeq
  • 5059 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
EventDataextend