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Elastic Docs ›Elastic Security Solution [8.13] ›Detections and alerts ›Prebuilt rule reference

Unusual Print Spooler Child Process

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Unusual Print Spooler Child Process

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Detects unusual Print Spooler service (spoolsv.exe) child processes. This may indicate an attempt to exploit privilege escalation vulnerabilities related to the Printing Service on Windows.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.process-*
  • logs-windows.*
  • logs-system.security*

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:

  • Domain: Endpoint
  • OS: Windows
  • Use Case: Threat Detection
  • Tactic: Privilege Escalation
  • Use Case: Vulnerability
  • Data Source: Elastic Defend
  • Data Source: System

Version: 109

Rule authors:

  • Elastic

Rule license: Elastic License v2

Setup

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Setup

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 version 8.2. Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate event.ingested to @timestamp. For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html

Rule query

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process where host.os.type == "windows" and event.type == "start" and
 process.parent.name : "spoolsv.exe" and process.command_line != null and
 (?process.Ext.token.integrity_level_name : "System" or ?winlog.event_data.IntegrityLevel : "System") and

 /* exclusions for FP control below */
 not process.name : ("splwow64.exe", "PDFCreator.exe", "acrodist.exe", "spoolsv.exe", "msiexec.exe", "route.exe", "WerFault.exe") and
 not process.command_line : "*\\WINDOWS\\system32\\spool\\DRIVERS*" and
 not (process.name : "net.exe" and process.command_line : ("*stop*", "*start*")) and
 not (process.name : ("cmd.exe", "powershell.exe") and process.command_line : ("*.spl*", "*\\program files*", "*route add*")) and
 not (process.name : "netsh.exe" and process.command_line : ("*add portopening*", "*rule name*")) and
 not (process.name : "regsvr32.exe" and process.command_line : "*PrintConfig.dll*") and
 not process.executable : (
    "?:\\Program Files (x86)\\CutePDF Writer\\CPWriter2.exe",
    "?:\\Program Files (x86)\\GPLGS\\gswin32c.exe"
 )

Framework: MITRE ATT&CKTM

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