UAC Bypass via DiskCleanup Scheduled Task Hijack

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UAC Bypass via DiskCleanup Scheduled Task Hijack

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Identifies User Account Control (UAC) bypass via hijacking DiskCleanup Scheduled Task. Attackers bypass UAC to stealthily execute code with elevated permissions.

Rule type: eql

Rule indices:

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

Severity: medium

Risk score: 47

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
  • Privilege Escalation

Version: 7 (version history)

Added (Elastic Stack release): 7.10.0

Last modified (Elastic Stack release): 8.2.0

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 == "start" and process.args : "/autoclean"
and process.args : "/d" and not process.executable :
("C:\\Windows\\System32\\cleanmgr.exe",
"C:\\Windows\\SysWOW64\\cleanmgr.exe",
"C:\\Windows\\System32\\taskhostw.exe")

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 7 (8.2.0 release)
  • Formatting only
Version 6 (7.15.0 release)
  • Formatting only
Version 5 (7.13.0 release)
  • Updated query, changed from:

    process where event.type in ("start", "process_started") and
    process.args:"/autoclean" and process.args:"/d" and not
    process.executable : ("C:\\Windows\\System32\\cleanmgr.exe",
    "C:\\Windows\\SysWOW64\\cleanmgr.exe")
Version 4 (7.12.0 release)
  • Formatting only
Version 3 (7.11.2 release)
  • Formatting only
Version 2 (7.11.0 release)
  • Updated query, changed from:

    event.category:process and event.type:(start or process_started) and
    process.args:(/autoclean or /AUTOCLEAN) and
    process.parent.name:svchost.exe and not
    process.executable:("C:\Windows\System32\cleanmgr.exe" or
    "C:\Windows\SysWOW64\cleanmgr.exe")