UAC Bypass via DiskCleanup Scheduled Task Hijack

Elastic Stack Serverless Security

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 (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[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

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.

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&CKTM

• 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/