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Detection rules › Sigma

UAC Bypass Using Windows Media Player - Process

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

Detects the pattern of UAC Bypass using Windows Media Player osksupport.dll (UACMe 32)

MITRE ATT&CK coverage

TacticTechniques
Privilege EscalationT1548.002 Abuse Elevation Control Mechanism: Bypass User Account Control

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: UAC Bypass Using Windows Media Player - Process
id: 0058b9e5-bcd7-40d4-9205-95ca5a16d7b2
status: test
description: Detects the pattern of UAC Bypass using Windows Media Player osksupport.dll (UACMe 32)
references:
    - https://github.com/hfiref0x/UACME
author: Christian Burkard (Nextron Systems)
date: 2021-08-23
modified: 2024-12-01
tags:
    - attack.privilege-escalation
    - attack.t1548.002
logsource:
    category: process_creation
    product: windows
detection:
    selection_img_1:
        Image: 'C:\Program Files\Windows Media Player\osk.exe'
    selection_img_2:
        Image: 'C:\Windows\System32\cmd.exe'
        ParentCommandLine: '"C:\Windows\system32\mmc.exe" "C:\Windows\system32\eventvwr.msc" /s'
    selection_integrity:
        IntegrityLevel:
            - 'High'
            - 'System'
            - 'S-1-16-16384' # System
            - 'S-1-16-12288' # High
    condition: 1 of selection_img_* and selection_integrity
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

1 of selection_img_* and selection_integrity

Stage 1: selection_img_1

selection_img_1:
    Image: 'C:\Program Files\Windows Media Player\osk.exe'

Stage 2: selection_img_2

selection_img_2:
    Image: 'C:\Windows\System32\cmd.exe'
    ParentCommandLine: '"C:\Windows\system32\mmc.exe" "C:\Windows\system32\eventvwr.msc" /s'

Stage 3: selection_integrity

selection_integrity:
    IntegrityLevel:
        - 'High'
        - 'System'
        - 'S-1-16-16384'
        - 'S-1-16-12288'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Imageeq
  • C:\Program Files\Windows Media Player\osk.exe
  • C:\Windows\System32\cmd.exe corpus 2 (sigma 2)
IntegrityLeveleq
  • 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 29 (sigma 22, splunk 4, elastic 3)
  • System corpus 29 (sigma 22, splunk 4, elastic 3)
ParentCommandLineeq
  • "C:\Windows\system32\mmc.exe" "C:\Windows\system32\eventvwr.msc" /s