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Unusual Service Host Child Process - Childless Service

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Unusual Service Host Child Process - Childless Service

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Identifies unusual child processes of Service Host (svchost.exe) that traditionally do not spawn any child processes. This may indicate a code injection or an equivalent form of exploitation.

Rule type: eql

Rule indices:

logs-endpoint.events.*
winlogbeat-*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion
Privilege Escalation

Version: 101 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Changes to Windows services or a rarely executed child process.

Investigation guide

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Rule query

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process where event.type == "start" and process.parent.name :
"svchost.exe" and /* based on svchost service arguments -s
svcname where the service is known to be childless */
process.parent.args : ("WdiSystemHost","LicenseManager",
"StorSvc","CDPSvc","cdbhsvc","BthAvctpSvc","SstpSvc","WdiServiceHost",
"imgsvc","TrkWks","WpnService","IKEEXT","PolicyAgent","CryptSvc",
"netprofm","ProfSvc","StateRepository","camsvc","LanmanWorkstation",
"NlaSvc","EventLog","hidserv","DisplayEnhancementService","ShellHWDete
ction", "AppHostSvc","fhsvc","CscService","PushToInstall") and
/* unknown FPs can be added here */ not process.name :
("WerFault.exe","WerFaultSecure.exe","wermgr.exe") and not
(process.executable : "?:\\Windows\\System32\\RelPost.exe" and
process.parent.args : "WdiSystemHost") and not (process.name :
"rundll32.exe" and process.args :
"?:\\WINDOWS\\System32\\winethc.dll,ForceProxyDetectionOnNextRun" and
process.parent.args : "WdiServiceHost") and not
(process.executable : ("?:\\Program Files\\*", "?:\\Program Files
(x86)\\*", "?:\\Windows\\System32\\Kodak\\kds_i4x50\\lib\\lexexe.exe")
and process.parent.args : "imgsvc")

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
Technique:
- Name: Process Injection
- ID: T1055
- Reference URL: https://attack.mitre.org/techniques/T1055/
Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Process Injection
- ID: T1055
- Reference URL: https://attack.mitre.org/techniques/T1055/

Rule version history

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Version 101 (8.5.0 release)

Updated query, changed from:

process where event.type in ("start", "process_started") and
process.parent.name : "svchost.exe" and /* based on svchost
service arguments -s svcname where the service is known to be
childless */ process.parent.args :
("WdiSystemHost","LicenseManager",
"StorSvc","CDPSvc","cdbhsvc","BthAvctpSvc","SstpSvc","WdiServiceHost",
"imgsvc","TrkWks","WpnService","IKEEXT","PolicyAgent","CryptSvc",
"netprofm","ProfSvc","StateRepository","camsvc","LanmanWorkstation",
"NlaSvc","EventLog","hidserv","DisplayEnhancementService","ShellHWDete
ction", "AppHostSvc","fhsvc","CscService","PushToInstall") and
/* unknown FPs can be added here */ not process.name :
("WerFault.exe","WerFaultSecure.exe","wermgr.exe") and not
(process.executable : "?:\\Windows\\System32\\RelPost.exe" and
process.parent.args : "WdiSystemHost") and not (process.name :
"rundll32.exe" and process.args :
"?:\\WINDOWS\\System32\\winethc.dll,ForceProxyDetectionOnNextRun" and
process.parent.args : "WdiServiceHost") and not
(process.executable : ("?:\\Program Files\\*", "?:\\Program Files
(x86)\\*", "?:\\Windows\\System32\\Kodak\\kds_i4x50\\lib\\lexexe.exe")
and process.parent.args : "imgsvc")

Version 6 (8.4.0 release)

Updated query, changed from:

process where event.type in ("start", "process_started") and
process.parent.name : "svchost.exe" and /* based on svchost
service arguments -s svcname where the service is known to be
childless */ process.parent.args :
("WdiSystemHost","LicenseManager",
"StorSvc","CDPSvc","cdbhsvc","BthAvctpSvc","SstpSvc","WdiServiceHost",
"imgsvc","TrkWks","WpnService","IKEEXT","PolicyAgent","CryptSvc",
"netprofm","ProfSvc","StateRepository","camsvc","LanmanWorkstation",
"NlaSvc","EventLog","hidserv","DisplayEnhancementService","ShellHWDete
ction", "AppHostSvc","fhsvc","CscService","PushToInstall") and
/* unknown FPs can be added here */ not process.name :
("WerFault.exe","WerFaultSecure.exe","wermgr.exe")

Version 4 (8.2.0 release)

Formatting only

Version 3 (7.12.0 release)

Formatting only

Version 2 (7.11.2 release)

Formatting only

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