Sigma Rule Library

Access To Chromium Browsers Sensitive Files By Uncommon Applications

Detects file access requests to chromium based browser sensitive files by uncommon processes. Could indicate potential attempt of stealing sensitive information.

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Detection logic

selection

FileName|contains:
  - \User Data\Default\Cookies
  - \User Data\Default\History
  - \User Data\Default\Network\Cookies
  - \User Data\Default\Web Data

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

Condition

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Raw YAML

title: Access To Chromium Browsers Sensitive Files By Uncommon Applications
id: c5f37810-a85f-4186-81e9-33f23abb4141
status: test
description: |
    Detects file access requests to chromium based browser sensitive files by uncommon processes.
    Could indicate potential attempt of stealing sensitive information.
references:
    - Internal Research
author: X__Junior (Nextron Systems)
date: 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:
        FileName|contains:
            - '\User Data\Default\Cookies'
            - '\User Data\Default\History'
            - '\User Data\Default\Network\Cookies'
            - '\User Data\Default\Web Data'
    filter_main_system:
        Image: System
    filter_main_generic:
        # This filter is added to avoid large amount of FP with 3rd party software. You should remove this in favour of specific filter per-application
        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'
    condition: 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

False positives

  • Antivirus, Anti-Spyware, Anti-Malware Software
  • Backup software
  • Legitimate software installed on partitions other than "C:\"
  • Searching software such as "everything.exe"

References

  • Internal Research

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