Conhost Spawned By Uncommon Parent Process

Status: test
Severity: medium
Log source: product windows, category process_creation
Author: Tim Rauch, Elastic (idea)
Source: github.com/SigmaHQ/sigma

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.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059` Command and Scripting Interpreter

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body 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

Stages and Predicates

Stage 0: `condition`

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

Stage 1: `selection`

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'

Stage 2: `not filter_main_svchost`

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'

Stage 3: `not filter_optional_dropbox`

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

Exclusions

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

Field	Kind	Excluded values
`ParentCommandLine`	match	`-k LocalSystemNetworkRestricted -p -s NgcSvc`
`ParentCommandLine`	match	`-k NetSvcs -p -s NcaSvc`
`ParentCommandLine`	match	`-k NetworkService -p -s DoSvc`
`ParentCommandLine`	match	`-k apphost -s AppHostSvc`
`ParentCommandLine`	match	`-k imgsvc`
`ParentCommandLine`	match	`-k localService -p -s RemoteRegistry`
`ParentCommandLine`	match	`-k netsvcs -p -s NetSetupSvc`
`ParentCommandLine`	match	`-k netsvcs -p -s wlidsvc`
`ParentCommandLine`	match	`-k wsappx -p -s AppXSvc`
`ParentCommandLine`	match	`-k wsappx -p -s ClipSVC`
`ParentCommandLine`	match	`-k wusvcs -p -s WaaSMedicSvc`
`ParentCommandLine`	match	`C:\Program Files (x86)\Dropbox\Client\`
`ParentCommandLine`	match	`C:\Program Files\Dropbox\Client\`

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.

Field	Kind	Values
`Image`	ends_with	`\conhost.exe` corpus 4 (sigma 4)
`ParentImage`	ends_with	`\explorer.exe` corpus 13 (sigma 13) `\lsass.exe` corpus 3 (sigma 3) `\regsvr32.exe` corpus 11 (sigma 11) `\rundll32.exe` corpus 15 (sigma 15) `\services.exe` corpus 8 (sigma 8) `\smss.exe` corpus 2 (sigma 2) `\spoolsv.exe` corpus 5 (sigma 5) `\svchost.exe` corpus 14 (sigma 14) `\userinit.exe` corpus 3 (sigma 3) `\wininit.exe` corpus 2 (sigma 2) `\winlogon.exe` corpus 5 (sigma 5)

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Conhost Spawned By Uncommon Parent Process

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_svchost`

Stage 3: `not filter_optional_dropbox`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Conhost Spawned By Uncommon Parent Process

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_svchost

Stage 3: not filter_optional_dropbox

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_svchost`

Stage 3: `not filter_optional_dropbox`