Possible Suspicious Change To Sensitive/Critical Files (via process_creation)

title: Possible Suspicious Change To Sensitive/Critical Files (via process_creation)
id: c2dd2dc4-8b21-59e5-badd-49edca8c828a
status: stable
description: This rule detects changes of sensitive and critical files. Monitors files that you don't expect to change without planning on Linux system. These files include, but are not limited to, system configuration files, authentication files, and critical application files. Attackers frequently target these files to maintain persistence, escalate privileges, or disrupt system operations.
references:
    - https://attack.mitre.org/techniques/T1565/001/
    - https://learn.microsoft.com/en-us/azure/defender-for-cloud/file-integrity-monitoring-overview#which-files-should-i-monitor
author: 'Huntrule Team'
date: 2026-04-24
tags:
    - attack.impact
    - attack.t1565.001
logsource:
    category: process_creation
    product: linux
detection:
    selection_img_1:
        Image|endswith:
            - '/cat'
            - '/echo'
            - '/grep'
            - '/head'
            - '/more'
            - '/tail'
        CommandLine|contains: '>'
    selection_img_2:
        Image|endswith:
            - '/emacs'
            - '/nano'
            - '/sed'
            - '/vi'
            - '/vim'
    selection_paths:
        CommandLine|contains:
            - '/bin/login'
            - '/bin/passwd'
            - '/boot/'
            - '/etc/*.conf'
            - '/etc/cron.'
            - '/etc/crontab'
            - '/etc/hosts'
            - '/etc/init.d'
            - '/etc/sudoers'
            - '/opt/bin/'
            - '/sbin'
            - '/usr/bin/'
            - '/usr/local/bin/'
    filter_main_mdadm.conf:
        Image|endswith: '/bin/sed'
        CommandLine|startswith:
            - 'sed -i /^*'
            - 'sed -ne s/^'
        CommandLine|endswith: '/etc/mdadm/mdadm.conf'
    condition: 1 of selection_img_* and selection_paths and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium