Uncommon Applications Access Windows DPAPI Master Key Files
Alerts on unusual process access to Windows DPAPI master key files under Microsoft\Protect.
- Product
- windows
- Category
- file_access
- Author
- Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
- Published
- 2022-10-17
- Updated
- 2026-07-31
ATT&CK techniques
Cred AccessRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule identifies file access to Windows DPAPI master key directories associated with the local system (S-1-5-18) and user profiles (S-1-5-21-) when the accessing process is not a common, expected application. Attackers may abuse DPAPI master keys to decrypt protected credentials, enabling credential theft and related follow-on activity. The detection relies on Windows file access telemetry that includes the accessed file path and the accessing process image.
Reporting behind it
- blog.harmj0y.nethttp://blog.harmj0y.net/redteaming/operational-guidance-for-offensive-user-dpapi-abuse/
- book.hacktricks.xyzhttps://book.hacktricks.xyz/windows-hardening/windows-local-privilege-escalation/dpapi-extracting-passwords
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_access/file_access_win_susp_dpapi_master_key_access.yml
Changelog
v2- v2Candidate ingested via manual entry.2026-07-31
- v1No changelog recorded for this version.2026-07-30
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: Uncommon Applications Access Windows DPAPI Master Key Files
id: c995bc04-a659-49c9-b1d8-a2f824cef5d1
status: test
description: This rule identifies file access to Windows DPAPI master key directories associated with the local system (S-1-5-18) and user profiles (S-1-5-21-) when the accessing process is not a common, expected application. Attackers may abuse DPAPI master keys to decrypt protected credentials, enabling credential theft and related follow-on activity. The detection relies on Windows file access telemetry that includes the accessed file path and the accessing process image.
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
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_access/file_access_win_susp_dpapi_master_key_access.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-10-17
modified: 2026-07-28
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_main_system_folders:
Image|startswith:
- C:\Program Files\
- C:\Program Files (x86)\
- C:\Windows\system32\
- C:\Windows\SysWOW64\
filter_main_explorer:
Image: C:\Windows\explorer.exe
condition: selection and not 1 of filter_main_*
falsepositives:
- Unknown
level: medium
license: DRL-1.1
related:
- id: 46612ae6-86be-4802-bc07-39b59feb1309
type: derived