CredUI.DLL Loaded By Uncommon Process — Sigma Rule

Rule metadata and linked tags

Author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research). Source status: test; severity: medium. Source dates: 2020-10-20 / 2025-12-09.

{
  "category": "image_load",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 703b6bbf227e8e702df2c134c9f5c48dc66ebfc40dce9dd835a6d5db5160623f

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: CredUI.DLL Loaded By Uncommon Process
id: 9ae01559-cf7e-4f8e-8e14-4c290a1b4784
status: test
description: Detects loading of "credui.dll" and related DLLs by an uncommon process. Attackers might leverage this DLL for potential use of "CredUIPromptForCredentials" or "CredUnPackAuthenticationBufferW".
references:
    - https://securitydatasets.com/notebooks/atomic/windows/credential_access/SDWIN-201020013208.html
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1056.002/T1056.002.md#atomic-test-2---powershell---prompt-user-for-password
    - https://learn.microsoft.com/en-us/windows/win32/api/wincred/nf-wincred-creduipromptforcredentialsa
    - https://github.com/S12cybersecurity/RDPCredentialStealer
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research)
date: 2020-10-20
modified: 2025-12-09
tags:
    - attack.credential-access
    - attack.collection
    - attack.t1056.002
logsource:
    category: image_load
    product: windows
detection:
    selection:
        - ImageLoaded|endswith:
              - '\credui.dll'
              - '\wincredui.dll'
        - OriginalFileName:
              - 'credui.dll'
              - 'wincredui.dll'
    filter_main_generic:
        Image|startswith:
            - 'C:\Program Files (x86)\'
            - 'C:\Program Files\'
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
            - 'C:\Windows\SystemApps\'
    filter_main_full:
        Image:
            - 'C:\Windows\explorer.exe'
            - 'C:\Windows\ImmersiveControlPanel\SystemSettings.exe'
            - 'C:\Windows\regedit.exe' # This FP is triggered for example when choosing the "Connect Network Registry" from the menu
    filter_optional_opera:
        Image|endswith: '\opera_autoupdate.exe'
    filter_optional_process_explorer:
        Image|endswith:
            - '\procexp64.exe'
            - '\procexp.exe'
    filter_optional_teams:
        Image|startswith: 'C:\Users\'
        Image|contains: '\AppData\Local\Microsoft\Teams\'
        Image|endswith: '\Teams.exe'
    filter_optional_onedrive:
        Image|startswith: 'C:\Users\'
        Image|contains: '\AppData\Local\Microsoft\OneDrive\'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Other legitimate processes loading those DLLs in your environment.
level: medium

Original YAML and metadata in JSON

False positives

• Other legitimate processes loading those DLLs in your environment.

Source references

• https://securitydatasets.com/notebooks/atomic/windows/credential_access/SDWIN-201020013208.html
• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1056.002/T1056.002.md#atomic-test-2---powershell---prompt-user-for-password
• https://learn.microsoft.com/en-us/windows/win32/api/wincred/nf-wincred-creduipromptforcredentialsa
• https://github.com/S12cybersecurity/RDPCredentialStealer