Detection rules › Kusto

Dev-0270 WMIC Discovery

Status
available
Severity
high
Time window
6h
Source
github.com/Azure/Azure-Sentinel

The query below identifies dllhost.exe using WMIC to discover additional hosts and associated domains in the environment.

MITRE ATT&CK coverage

TacticTechniques
DiscoveryT1482 Domain Trust Discovery

Event coverage

Rule body kusto

id: 6b652b4f-9810-4eec-9027-7aa88ce4db23
name: Dev-0270 WMIC  Discovery
description: | 
  'The query below identifies dllhost.exe using WMIC to discover additional hosts and associated domains in the environment.'
severity: High 
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceProcessEvents
queryFrequency: 6h 
queryPeriod: 6h 
triggerOperator: gt 
triggerThreshold: 0 
status: Available
tactics: 
  - Discovery
relevantTechniques:
  - T1482
tags:
  - Dev-0270
query: |
  (union isfuzzy=true
  (SecurityEvent
  | where EventID==4688
  | where CommandLine has "wmic computersystem get domain" and ParentProcessName has "dllhost.exe"
  | project TimeGenerated, Computer, Account, AccountDomain, ProcessName, ProcessNameFullPath = NewProcessName, EventID, Activity, CommandLine, EventSourceName, Type
  ),
  (DeviceProcessEvents 
  | where ProcessCommandLine has "wmic computersystem get domain" and InitiatingProcessFileName =~ "dllhost.exe" and InitiatingProcessCommandLine has "dllhost.exe"
  | extend Account = strcat(InitiatingProcessAccountDomain, @'\', InitiatingProcessAccountName), Computer = DeviceName
  )
  )
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | extend AccountName = tostring(split(Account, @'\')[1]), AccountNTDomain = tostring(split(Account, @'\')[0])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Account
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountNTDomain
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
version: 1.0.4
kind: Scheduled

Stages and Predicates

union isfuzzy=true (2 sources)

Each leg below queries one source; the rule matches if any leg does. Sources: SecurityEvent, DeviceProcessEvents

Leg 1: SecurityEvent

SecurityEvent
| where EventID==4688
| where CommandLine has "wmic computersystem get domain" and ParentProcessName has "dllhost.exe"
| project TimeGenerated, Computer, Account, AccountDomain, ProcessName, ProcessNameFullPath = NewProcessName, EventID, Activity, CommandLine, EventSourceName, Type

Leg 2: DeviceProcessEvents

DeviceProcessEvents 
| where ProcessCommandLine has "wmic computersystem get domain" and InitiatingProcessFileName =~ "dllhost.exe" and InitiatingProcessCommandLine has "dllhost.exe"
| extend Account = strcat(InitiatingProcessAccountDomain, @'\', InitiatingProcessAccountName), Computer = DeviceName

Applied to the combined result

| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(Account, @'\')[1]), AccountNTDomain = tostring(split(Account, @'\')[0])

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
CommandLinematch
  • wmic computersystem get domain transforms: term
EventIDeq
  • 4688 transforms: cased corpus 313 (splunk 283, kusto 30)
InitiatingProcessCommandLinematch
  • dllhost.exe transforms: term corpus 2 (kusto 2)
InitiatingProcessFileNameeq
  • dllhost.exe corpus 7 (elastic 4, kusto 2, splunk 1)
ParentProcessNamematch
  • dllhost.exe transforms: term
ProcessCommandLinematch
  • wmic computersystem get domain transforms: term

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
Accountextend
AccountDomainproject
Activityproject
CommandLineproject
Computerextend
EventIDproject
EventSourceNameproject
ProcessNameproject
ProcessNameFullPathproject
TimeGeneratedproject
Typeproject
DomainIndexextend
HostNameextend
HostNameDomainextend
AccountNTDomainextend
AccountNameextend