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Suspicious Process Creation CallTrace

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Suspicious Process Creation CallTrace

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Identifies when a process is created and immediately accessed from an unknown memory code region and by the same parent process. This may indicate a code injection or hollowing attempt.

Rule type: eql

Rule indices:

winlogbeat-*
logs-windows.*

Severity: medium

Risk score: 43

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

Version: 4 (version history)

Added (Elastic Stack release): 8.0.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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sequence by host.id with maxspan=1m [process where event.code == "1"
and /* sysmon process creation */ process.parent.name :
("winword.exe", "excel.exe", "outlook.exe", "powerpnt.exe",
"eqnedt32.exe", "fltldr.exe", "mspub.exe",
"msaccess.exe","cscript.exe", "wscript.exe", "rundll32.exe",
"regsvr32.exe", "mshta.exe", "wmic.exe",
"cmstp.exe", "msxsl.exe") and /* noisy FP patterns */ not
(process.parent.name : "EXCEL.EXE" and process.executable :
"?:\\Program Files\\Microsoft Office\\root\\Office*\\ADDINS\\*.exe")
and not (process.executable : "?:\\Windows\\splwow64.exe" and
process.args in ("8192", "12288") and process.parent.name :
("winword.exe", "excel.exe", "outlook.exe", "powerpnt.exe")) and
not (process.parent.name : "rundll32.exe" and process.parent.args : ("
?:\\WINDOWS\\Installer\\MSI*.tmp,zzzzInvokeManagedCustomActionOutOfPro
c", "--no-sandbox")) and not (process.executable :
("?:\\Program Files
(x86)\\Microsoft\\EdgeWebView\\Application\\*\\msedgewebview2.exe",
"?:\\Program Files\\Adobe\\Acrobat DC\\Acrobat\\Acrobat.exe",
"?:\\Windows\\SysWOW64\\DWWIN.EXE") and process.parent.name :
("winword.exe", "excel.exe", "outlook.exe", "powerpnt.exe")) and
not (process.parent.name : "regsvr32.exe" and process.parent.args :
("?:\\Program Files\\*", "?:\\Program Files (x86)\\*")) ] by
process.parent.entity_id, process.entity_id [process where
event.code == "10" and /* Sysmon process access event from unknown
module */ winlog.event_data.CallTrace : "*UNKNOWN*"] by
process.entity_id, winlog.event_data.TargetProcessGUID

Threat mapping

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Framework: MITRE ATT&CK^TM

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 4 (8.4.0 release)

Updated query, changed from:

sequence by host.id with maxspan=1m [process where event.code == "1"
and /* sysmon process creation */ process.parent.name :
("winword.exe", "excel.exe", "outlook.exe", "powerpnt.exe",
"eqnedt32.exe", "fltldr.exe", "mspub.exe",
"msaccess.exe", "powershell.exe", "pwsh.exe",
"cscript.exe", "wscript.exe", "rundll32.exe", "regsvr32.exe",
"mshta.exe", "wmic.exe", "cmstp.exe",
"msxsl.exe")] by process.parent.entity_id, process.entity_id
[process where event.code == "10" and /* Sysmon process access
event from unknown module */ winlog.event_data.CallTrace :
"*UNKNOWN*"] by process.entity_id, winlog.event_data.TargetProcessGUID

Version 2 (8.2.0 release)

Formatting only

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