Sigma Rule Library

Conhost Spawned By Uncommon Parent Process

Detects when the Console Window Host (conhost.exe) process is spawned by an uncommon parent process, which could be indicative of potential code injection activity.

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Detection logic

selection

Image|endswith: \conhost.exe
ParentImage|endswith:
  - \explorer.exe
  - \lsass.exe
  - \regsvr32.exe
  - \rundll32.exe
  - \services.exe
  - \smss.exe
  - \spoolsv.exe
  - \svchost.exe
  - \userinit.exe
  - \wininit.exe
  - \winlogon.exe

filter_main_svchost

ParentCommandLine|contains:
  - -k apphost -s AppHostSvc
  - -k imgsvc
  - -k localService -p -s RemoteRegistry
  - -k LocalSystemNetworkRestricted -p -s NgcSvc
  - -k NetSvcs -p -s NcaSvc
  - -k netsvcs -p -s NetSetupSvc
  - -k netsvcs -p -s wlidsvc
  - -k NetworkService -p -s DoSvc
  - -k wsappx -p -s AppXSvc
  - -k wsappx -p -s ClipSVC
  - -k wusvcs -p -s WaaSMedicSvc

filter_optional_dropbox

ParentCommandLine|contains:
  - C:\Program Files (x86)\Dropbox\Client\
  - C:\Program Files\Dropbox\Client\

Condition

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Raw YAML

title: Conhost Spawned By Uncommon Parent Process
id: cbb9e3d1-2386-4e59-912e-62f1484f7a89
status: test
description: Detects when the Console Window Host (conhost.exe) process is spawned by an uncommon parent process, which could be indicative of potential code injection activity.
references:
    - https://www.elastic.co/guide/en/security/current/conhost-spawned-by-suspicious-parent-process.html
author: Tim Rauch, Elastic (idea)
date: 2022-09-28
modified: 2025-03-06
tags:
    - attack.execution
    - attack.t1059
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\conhost.exe'
        ParentImage|endswith:
            - '\explorer.exe'
            # - '\csrss.exe'  # Legitimate parent as seen in EchoTrail https://www.echotrail.io/insights/search/csrss.exe
            # - '\ctfmon.exe'  # Seen several times in a testing environment
            # - '\dllhost.exe'  # FP on clean system from grandparent 'svchost.exe -k DcomLaunch -p'
            - '\lsass.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            - '\services.exe'
            - '\smss.exe'
            - '\spoolsv.exe'
            - '\svchost.exe'
            - '\userinit.exe'
            # - '\wermgr.exe'  # Legitimate parent as seen in EchoTrail https://www.echotrail.io/insights/search/wermgr.exe
            - '\wininit.exe'
            - '\winlogon.exe'
    filter_main_svchost:
        ParentCommandLine|contains:
            - '-k apphost -s AppHostSvc'
            - '-k imgsvc'
            - '-k localService -p -s RemoteRegistry'
            - '-k LocalSystemNetworkRestricted -p -s NgcSvc'
            - '-k NetSvcs -p -s NcaSvc'
            - '-k netsvcs -p -s NetSetupSvc'
            - '-k netsvcs -p -s wlidsvc'
            - '-k NetworkService -p -s DoSvc'
            - '-k wsappx -p -s AppXSvc'
            - '-k wsappx -p -s ClipSVC'
            - '-k wusvcs -p -s WaaSMedicSvc'
    filter_optional_dropbox:
        ParentCommandLine|contains:
            - 'C:\Program Files (x86)\Dropbox\Client\'
            - 'C:\Program Files\Dropbox\Client\'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

False positives

  • Unknown

References

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