UAC Bypass Abusing Winsat Path Parsing - Process

Hunt Hypothesis

Detects the pattern of UAC Bypass using a path parsing issue in winsat.exe (UACMe 52)

Detection Rule

Sigma (Original)

title: UAC Bypass Abusing Winsat Path Parsing - Process
id: 7a01183d-71a2-46ad-ad5c-acd989ac1793
status: test
description: Detects the pattern of UAC Bypass using a path parsing issue in winsat.exe (UACMe 52)
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:
        IntegrityLevel:
            - 'High'
            - 'System'
            - 'S-1-16-16384' # System
            - 'S-1-16-12288' # High
        ParentImage|endswith: '\AppData\Local\Temp\system32\winsat.exe'
        ParentCommandLine|contains: 'C:\Windows \system32\winsat.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imProcessCreate
| where (TargetProcessIntegrityLevel in~ ("High", "System", "S-1-16-16384", "S-1-16-12288")) and (ParentProcessName endswith "\\AppData\\Local\\Temp\\system32\\winsat.exe" or ActingProcessName endswith "\\AppData\\Local\\Temp\\system32\\winsat.exe") and ActingProcessCommandLine contains "C:\\Windows \\system32\\winsat.exe"

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Privilege Escalation
• Technique: T1548.002 — T1548.002

References

• https://github.com/hfiref0x/UACME
• SigmaHQ Rule