Convert indexed Sigma rules into analyst-ready detections.

title: Access To Windows Outlook Mail Files By Uncommon Applications
id: fc3e237f-2fef-406c-b90d-b3ae7e02fa8f
status: test
description: |
    Detects file access requests to Windows Outlook Mail by uncommon processes.
    Could indicate potential attempt of credential stealing.
    Requires heavy baselining before usage
references:
    - https://darkdefender.medium.com/windows-10-mail-app-forensics-39025f5418d2
    - https://github.com/redcanaryco/atomic-red-team/blob/58496ee3306e6e42a7054d36a94e6eb561ee3081/atomics/T1070.008/T1070.008.md#atomic-test-4---copy-and-modify-mailbox-data-on-windows
author: frack113
date: 2024-05-10
modified: 2024-07-29
tags:
    - attack.t1070.008
    - attack.defense-evasion
    - detection.threat-hunting
logsource:
    category: file_access
    product: windows
    definition: 'Requirements: Microsoft-Windows-Kernel-File ETW provider'
detection:
    selection_unistore:
        FileName|contains: '\AppData\Local\Comms\Unistore\data'
    selection_unistoredb:
        FileName|endswith: '\AppData\Local\Comms\UnistoreDB\store.vol'
    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'
    filter_optional_thor:
        Image|endswith:
            - '\thor64.exe'
            - '\thor.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"
# Note: Increase after initial baseline
level: low