UAC Bypass Using Disk Cleanup

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Christian Burkard (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the pattern of UAC Bypass using scheduled tasks and variable expansion of cleanmgr.exe (UACMe 34)

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1548.002` Abuse Elevation Control Mechanism: Bypass User Account Control

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: UAC Bypass Using Disk Cleanup
id: b697e69c-746f-4a86-9f59-7bfff8eab881
status: test
description: Detects the pattern of UAC Bypass using scheduled tasks and variable expansion of cleanmgr.exe (UACMe 34)
references:
    - https://github.com/hfiref0x/UACME
author: Christian Burkard (Nextron Systems)
date: 2021-08-30
modified: 2024-12-01
tags:
    - attack.privilege-escalation
    - attack.t1548.002
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|endswith: '"\system32\cleanmgr.exe /autoclean /d C:'
        ParentCommandLine: 'C:\Windows\system32\svchost.exe -k netsvcs -p -s Schedule'
        IntegrityLevel:
            - 'High'
            - 'System'
            - 'S-1-16-16384' # System
            - 'S-1-16-12288' # High
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    CommandLine|endswith: '"\system32\cleanmgr.exe /autoclean /d C:'
    ParentCommandLine: 'C:\Windows\system32\svchost.exe -k netsvcs -p -s Schedule'
    IntegrityLevel:
        - 'High'
        - 'System'
        - 'S-1-16-16384'
        - 'S-1-16-12288'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	ends_with	`"\system32\cleanmgr.exe /autoclean /d C:`	`field:"CommandLine" kind:ends_with`
`IntegrityLevel`	eq	`High` corpus 21 (sigma 17, kusto 3, splunk 1) `S-1-16-12288` corpus 21 (sigma 17, kusto 3, splunk 1) `S-1-16-16384` corpus 30 (sigma 22, splunk 4, elastic 3, kusto 1) `System` corpus 30 (sigma 22, splunk 4, elastic 3, kusto 1)	`field:"IntegrityLevel" kind:eq`
`ParentCommandLine`	eq	`C:\Windows\system32\svchost.exe -k netsvcs -p -s Schedule`	`field:"ParentCommandLine" kind:eq value:"C:\Windows\system32\svchost.exe -k netsvcs -p -s Schedule"`

UAC Bypass Using Disk Cleanup

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`