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Access To Windows DPAPI Master Keys By Uncommon Applications

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 usage of mimikatz "dpapi::masterkey" function

MITRE ATT&CK

T1555.004

credential-access

Detection Query

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_*

Author

Nasreddine Bencherchali (Nextron Systems)

Created

2022-10-17

Data Sources

windowsfile_access

Platforms

windows

References

Tags

attack.credential-accessattack.t1555.004

Raw Content

title: Access To Windows DPAPI Master Keys By Uncommon Applications
id: 46612ae6-86be-4802-bc07-39b59feb1309
status: test
description: |
    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 usage of mimikatz "dpapi::masterkey" function
references:
    - 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: Nasreddine Bencherchali (Nextron Systems)
date: 2022-10-17
modified: 2024-07-29
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\' # For System32
            - '\Microsoft\Protect\S-1-5-21-' # For Users
    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
# Increase level after false positives filters are good enough
level: medium