UAC Bypass With Fake DLL

Hunt Hypothesis

Attempts to load dismcore.dll after dropping it

Detection Rule

Sigma (Original)

title: UAC Bypass With Fake DLL
id: a5ea83a7-05a5-44c1-be2e-addccbbd8c03
status: test
description: Attempts to load dismcore.dll after dropping it
references:
    - https://steemit.com/utopian-io/@ah101/uac-bypassing-utility
author: oscd.community, Dmitry Uchakin
date: 2020-10-06
modified: 2022-12-25
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.execution
    - attack.stealth
    - attack.t1548.002
    - attack.t1574.001
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith: '\dism.exe'
        ImageLoaded|endswith: '\dismcore.dll'
    filter:
        ImageLoaded: 'C:\Windows\System32\Dism\dismcore.dll'
    condition: selection and not filter
falsepositives:
    - Actions of a legitimate telnet client
level: high

KQL (Microsoft 365 Defender)

DeviceImageLoadEvents
| where (InitiatingProcessFolderPath endswith "\\dism.exe" and FolderPath endswith "\\dismcore.dll") and (not(FolderPath =~ "C:\\Windows\\System32\\Dism\\dismcore.dll"))

Required Data Sources

False Positive Guidance

• Actions of a legitimate telnet client

MITRE ATT&CK Context

• Tactic: Persistence
• Tactic: Privilege Escalation
• Tactic: Execution
• Technique: T1548.002 — T1548.002
• Technique: T1574.001 — T1574.001

References

• https://steemit.com/utopian-io/@ah101/uac-bypassing-utility
• SigmaHQ Rule