UAC Bypass via DiskCleanup Scheduled Task Hijack

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: 5m

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

Maximum alerts per execution: 100

References: None

Tags:

Elastic
Host
Windows
Threat Detection
Privilege Escalation

Version: 7

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")

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
Technique:
- Name: Abuse Elevation Control Mechanism
- ID: T1548
- Reference URL: https://attack.mitre.org/techniques/T1548/
Sub-technique:
- Name: Bypass User Account Control
- ID: T1548.002
- Reference URL: https://attack.mitre.org/techniques/T1548/002/

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