Windows File Access to Browser Credential Stores by Uncommon Processes
Detects suspicious process access to Firefox/Chromium credential store files on Windows, excluding common system and known benign paths.
- Product
- windows
- Category
- file_access
- Author
- frack113, X__Junior (Nextron Systems) (SigmaHQ), DRL 1.1
- Published
- 2022-04-09
- 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 flags Windows file access events where a process reads specific browser credential-related files, such as Firefox cookies/places databases and Chromium Login Data/Local State, or the WebCache data file. Credential-stealing attempts often begin by directly accessing these on-disk browser stores, so unusual process access can indicate malicious collection. It relies on Microsoft-Windows-Kernel-File ETW telemetry containing the accessed FileName and the initiating Image, with process allowlisting to reduce noise.
Reporting behind it
Changelog
v5- v5Candidate ingested via manual entry.2026-07-31
- v4Candidate ingested via manual entry.2026-07-31
- v3Candidate ingested via manual entry.2026-07-31
- 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: Windows File Access to Browser Credential Stores by Uncommon Processes
id: 4544308a-58d3-4224-8a39-98f29bbb1cab
related:
- id: 4b60e527-ec73-4b47-8cb3-f02ad927ca65
type: similar
- id: 91cb43db-302a-47e3-b3c8-7ede481e27bf
type: derived
status: test
description: This rule flags Windows file access events where a process reads specific browser credential-related files, such as Firefox cookies/places databases and Chromium Login Data/Local State, or the WebCache data file. Credential-stealing attempts often begin by directly accessing these on-disk browser stores, so unusual process access can indicate malicious collection. It relies on Microsoft-Windows-Kernel-File ETW telemetry containing the accessed FileName and the initiating Image, with process allowlisting to reduce noise.
references:
- https://www.zscaler.com/blogs/security-research/ffdroider-stealer-targeting-social-media-platform-users
- https://github.com/lclevy/firepwd
- https://github.com/SigmaHQ/sigma/blob/master/rules-threat-hunting/windows/file/file_access/file_access_win_browsers_credential.yml
author: frack113, X__Junior (Nextron Systems), Huntrule Team
date: 2022-04-09
modified: 2024-07-29
tags:
- attack.t1003
- attack.credential-access
- detection.threat-hunting
logsource:
category: file_access
product: windows
definition: "Requirements: Microsoft-Windows-Kernel-File ETW provider"
detection:
selection_ie:
FileName|endswith: \Appdata\Local\Microsoft\Windows\WebCache\WebCacheV01.dat
selection_firefox:
FileName|endswith:
- \cookies.sqlite
- \places.sqlite
- release\key3.db
- release\key4.db
- release\logins.json
selection_chromium:
FileName|contains:
- \User Data\Default\Login Data
- \User Data\Local State
filter_main_system:
Image: System
filter_main_generic:
Image|startswith:
- C:\Program Files (x86)\
- C:\Program Files\
- C:\Windows\system32\
- C:\Windows\SysWOW64\
filter_optional_defender:
Image|startswith: C:\ProgramData\Microsoft\Windows Defender\
Image|endswith:
- \MpCopyAccelerator.exe
- \MsMpEng.exe
filter_optional_thor:
Image|endswith:
- \thor.exe
- \thor64.exe
condition: 1 of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
- Antivirus, Anti-Spyware, Anti-Malware Software
- Backup software
- Legitimate software installed on partitions other than "C:\"
- Searching software such as "everything.exe"
level: low
license: DRL-1.1