Access To Windows DPAPI Master Keys By Unusual Applications (via file_access)

title: Access To Windows DPAPI Master Keys By Unusual Applications (via file_access)
id: a586bf87-496f-5f7c-b652-5582c7a9c20d
status: stable
description: This rule detects file access requests to the the Windows Data Protection API Master keys by an uncommon application. This can be a sign of credential stealing. Example case would be use of mimikatz "dpapi::masterkey" function
references:
    - https://attack.mitre.org/techniques/T1555/004/
    - http://blog.harmj0y.net/redteaming/operational-guidance-for-offensive-user-dpapi-abuse/
    - https://book.hacktricks.xyz/windows-hardening/windows-local-privilege-escalation/dpapi-extracting-passwords
author: Huntrule Team
date: 2026-03-12
tags:
    - attack.credential-access
    - attack.t1555.004
logsource:
    category: file_access
    product: windows
    definition: 'Requirements: Microsoft-Windows-Kernel-File ETW provider'
detection:
    selection:
        FileName|contains:
            - '\Microsoft\Protect\S-1-5-18\'
            - '\Microsoft\Protect\S-1-5-21-'
    filter_system_folders:
        Image|startswith:
            - 'C:\Program Files\'
            - 'C:\Program Files (x86)\'
            - 'C:\Windows\system32\'
            - 'C:\Windows\SysWOW64\'
    condition: selection and not 1 of filter_*
falsepositives:
    - Unknown
level: medium