[Rule Tuning] Unusual Parent-Child Relationship#6394
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⛔️ Test failed Results
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Pull request overview
Tunes the existing Windows EQL rule “Unusual Parent-Child Relationship” to reduce alert noise caused by known benign parent/child patterns and data quality issues.
Changes:
- Adds a top-level filter to suppress events where
process.parent.nameappears as a SID (S-1-*). - Expands multiple “expected parent” allow-lists for system processes and “expected child” allow-lists for
conhost.exe. - Adds additional known-good parents for
svchost.exe(Computrace/Absoluterpcnet*).
| (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:("fontdrvhost.exe", "dwm.exe") and not process.parent.name:("wininit.exe", "winlogon.exe", "dwm.exe", "svchost.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:("fontdrvhost.exe", "dwm.exe") and not process.parent.name:("wininit.exe", "winlogon.exe", "dwm.exe", "svchost.exe")) or | ||
| (process.name:("consent.exe", "RuntimeBroker.exe", "TiWorker.exe") and not process.parent.name:("svchost.exe", "Workplace Container Helper.exe", "RuntimeBroker.exe", "TiWorker.exe")) or |
| (process.name:"taskhostw.exe" and not process.parent.name:("services.exe", "svchost.exe", "taskhostw.exe")) or | ||
| (process.name:"userinit.exe" and not process.parent.name:("dwm.exe", "winlogon.exe", "KUsrInit.exe")) or | ||
| (process.name:("wmiprvse.exe", "wsmprovhost.exe", "winrshost.exe") and not process.parent.name:"svchost.exe") or | ||
| (process.name:("wmiprvse.exe", "wsmprovhost.exe", "winrshost.exe") and not process.parent.name:("svchost.exe", "wmiprvse.exe", "wsmprovhost.exe")) or |
Mikaayenson
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Rule: Tuning
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Rule: Tuning - GuidelinesThese guidelines serve as a reminder set of considerations when tuning an existing rule. Documentation and Context
Rule Metadata Checks
Testing and Validation
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⛔️ Test failed Results
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w0rk3r
reviewed
Jul 6, 2026
| query = ''' | ||
| process where host.os.type == "windows" and event.type == "start" and | ||
| process.parent.name != null and process.parent.executable like ("?:\\*", "\\Device\\*") and | ||
| not process.parent.name like "S-1-*" and |
Contributor
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Already addressed by process.parent.executable like ("?:\\*", "\\Device\\*")
| (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:("fontdrvhost.exe", "dwm.exe") and not process.parent.name:("wininit.exe", "winlogon.exe", "dwm.exe", "svchost.exe")) or |
| (process.parent.name:"wermgr.exe" and not process.name:("WerFaultSecure.exe", "wermgr.exe", "WerFault.exe") and | ||
| not (process.name:"rundll32.exe" and process.command_line : "*WerConCpl.dll*LaunchErcApp*")) or | ||
| (process.parent.name:"conhost.exe" and not process.name:("mscorsvw.exe", "wermgr.exe", "WerFault.exe", "WerFaultSecure.exe", "conhost.exe")) | ||
| (process.parent.name:"conhost.exe" and not process.name:("mscorsvw.exe", "wermgr.exe", "WerFault.exe", "WerFaultSecure.exe", "conhost.exe", "cmd.exe", "powershell.exe")) |
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Suggested change
| (process.parent.name:"conhost.exe" and not process.name:("mscorsvw.exe", "wermgr.exe", "WerFault.exe", "WerFaultSecure.exe", "conhost.exe", "cmd.exe", "powershell.exe")) | |
| (process.parent.name:"conhost.exe" and not process.name:("mscorsvw.exe", "wermgr.exe", "WerFault.exe", "WerFaultSecure.exe", "conhost.exe")) |
Seems too broad
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Resolves elastic/ia-trade-team#991
Reduces noise from SID-as-parent data quality issues, legitimate Windows self-spawn pairs, headless conhost spawning cmd/powershell, and Computrace BIOS-level software (rpcnet/rpcnetp). Adds a top-level S-1-* parent name filter, expands allowed-parent lists for system processes to cover self-spawn scenarios (wmiprvse, dllhost, taskhostw, spoolsv, SearchIndexer, SearchProtocolHost, LogonUI, RuntimeBroker, TiWorker, wsmprovhost), adds rpcnet.exe and rpcnetp.exe as known-good parents for svchost, adds svchost.exe as an allowed parent for dwm.exe, and adds cmd.exe and powershell.exe to the conhost.exe allowed-children list.
Full telemetry triage, analytics links, and KQL verification: see linked ia-trade-team issue.