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Elastic Docs ›Elastic Security Solution [8.x] ›Downloadable rule update v1.0.2

Unusual Parent-Child Relationship

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Unusual Parent-Child Relationship

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Identifies Windows programs run from unexpected parent processes. This could indicate masquerading or other strange activity on a system.

Rule type: eql

Rule indices:

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

Severity: medium

Risk score: 47

Runs every: 5m

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

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Privilege Escalation

Version: 11

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

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process where event.type in ("start", "process_started") and
process.parent.name != null and
 (
   /* suspicious parent processes */
   (process.name:"autochk.exe" and not process.parent.name:"smss.exe") or
   (process.name:("fontdrvhost.exe", "dwm.exe") and not process.parent.name:("wininit.exe", "winlogon.exe")) or
   (process.name:("consent.exe", "RuntimeBroker.exe", "TiWorker.exe") and not process.parent.name:"svchost.exe") or
   (process.name:"SearchIndexer.exe" and not process.parent.name:"services.exe") or
   (process.name:"SearchProtocolHost.exe" and not process.parent.name:("SearchIndexer.exe", "dllhost.exe")) or
   (process.name:"dllhost.exe" and not process.parent.name:("services.exe", "svchost.exe")) or
   (process.name:"smss.exe" and not process.parent.name:("System", "smss.exe")) or
   (process.name:"csrss.exe" and not process.parent.name:("smss.exe", "svchost.exe")) or
   (process.name:"wininit.exe" and not process.parent.name:"smss.exe") or
   (process.name:"winlogon.exe" and not process.parent.name:"smss.exe") or
   (process.name:("lsass.exe", "LsaIso.exe") and not process.parent.name:"wininit.exe") or
   (process.name:"LogonUI.exe" and not process.parent.name:("wininit.exe", "winlogon.exe")) or
   (process.name:"services.exe" and not process.parent.name:"wininit.exe") or
   (process.name:"svchost.exe" and not process.parent.name:("MsMpEng.exe", "services.exe")) or
   (process.name:"spoolsv.exe" and not process.parent.name:"services.exe") or
   (process.name:"taskhost.exe" and not process.parent.name:("services.exe", "svchost.exe")) or
   (process.name:"taskhostw.exe" and not process.parent.name:("services.exe", "svchost.exe")) or
   (process.name:"userinit.exe" and not process.parent.name:("dwm.exe", "winlogon.exe")) or
   (process.name:("wmiprvse.exe", "wsmprovhost.exe", "winrshost.exe") and not process.parent.name:"svchost.exe") or
   /* suspicious child processes */
   (process.parent.name:("SearchProtocolHost.exe", "taskhost.exe", "csrss.exe") and not process.name:("werfault.exe", "wermgr.exe", "WerFaultSecure.exe")) or
   (process.parent.name:"autochk.exe" and not process.name:("chkdsk.exe", "doskey.exe", "WerFault.exe")) or
   (process.parent.name:"smss.exe" and not process.name:("autochk.exe", "smss.exe", "csrss.exe", "wininit.exe", "winlogon.exe", "setupcl.exe", "WerFault.exe")) or
   (process.parent.name:"wermgr.exe" and not process.name:("WerFaultSecure.exe", "wermgr.exe", "WerFault.exe")) or
   (process.parent.name:"conhost.exe" and not process.name:("mscorsvw.exe", "wermgr.exe", "WerFault.exe", "WerFaultSecure.exe"))
  )

Framework: MITRE ATT&CKTM

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