EVTX Created In Uncommon Location

title: EVTX Created In Uncommon Location
id: 65236ec7-ace0-4f0c-82fd-737b04fd4dcb
status: test
description: |
    Detects the creation of new files with the ".evtx" extension in non-common or non-standard location.
    This could indicate tampering with default EVTX locations in order to evade security controls or simply exfiltration of event log to search for sensitive information within.
    Note that backup software and legitimate administrator might perform similar actions during troubleshooting.
references:
    - https://learn.microsoft.com/en-us/windows/win32/eventlog/eventlog-key
author: D3F7A5105
date: 2023-01-02
modified: 2024-03-26
tags:
    - attack.defense-impairment
    - attack.t1685.001
logsource:
    category: file_event
    product: windows
    definition: 'Requirements: The ".evtx" extension should be monitored via a Sysmon configuration. Example: <TargetFilename condition="end with">.evtx<TargetFilename>'
detection:
    selection:
        TargetFilename|endswith: '.evtx'
    filter_main_path:
        TargetFilename|startswith: 'C:\Windows\System32\winevt\Logs\'
    filter_main_baseimage:
        TargetFilename|startswith: 'C:\ProgramData\Microsoft\Windows\Containers\BaseImages\'
        TargetFilename|endswith: '\Windows\System32\winevt\Logs\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Administrator or backup activity
    - An unknown bug seems to trigger the Windows "svchost" process to drop EVTX files in the "C:\Windows\Temp" directory in the form "<log_name">_<uuid>.evtx". See https://superuser.com/questions/1371229/low-disk-space-after-filling-up-c-windows-temp-with-evtx-and-txt-files
level: medium
regression_tests_path: regression_data/rules/windows/file/file_event/file_event_win_create_evtx_non_common_locations/info.yml