Unusual Child Processes of RunDLL32

Identifies child processes of unusual instances of RunDLL32 where the command line parameters were suspicious. Misuse of RunDLL32 could indicate malicious activity.

Rule type: eql

Rule indices:

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

Severity: high

Risk score: 21

Runs every: 30 minutes

Searches indices from: now-60m (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): 7.10.0

Last modified (Elastic Stack release): 7.14.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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sequence with maxspan=1h [process where event.type in ("start",
"process_started") and (process.name : "rundll32.exe" or
process.pe.original_file_name == "RUNDLL32.EXE") and
process.args_count == 1 ] by process.entity_id [process where
event.type in ("start", "process_started") and process.parent.name :
"rundll32.exe" ] by process.parent.entity_id

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: Signed Binary Proxy Execution
- ID: T1218
- Reference URL: https://attack.mitre.org/techniques/T1218/

Rule version history

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Version 4 (7.14.0 release)

Formatting only

Version 3 (7.12.0 release)

Formatting only

Version 2 (7.11.0 release)

Updated query, changed from:

sequence with maxspan=1h [process where event.type in ("start",
"process_started") and /*
uncomment once in winlogbeat */ (process.name : "rundll32.exe" /*
or process.pe.original_file_name == "RUNDLL32.EXE" */ ) and
process.args_count < 2 ] by process.entity_id [process where
event.type in ("start", "process_started") and process.parent.name :
"rundll32.exe" ] by process.parent.entity_id

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