title: Chmod Targeting Sensitive Directories
id: 6419afd1-3742-47a5-a7e6-b50386cd15f8
status: test
description: |
    Detects chmod targeting files in sensitive directory paths on Linux systems.
    Attackers may use chmod to change permissions of files in these directories to maintain persistence, escalate privileges, or disrupt system operations.
references:
    - https://www.intezer.com/blog/malware-analysis/new-backdoor-sysjoker/
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1222.002/T1222.002.md
author: 'Christopher Peacock @SecurePeacock, SCYTHE @scythe_io'
date: 2022-06-03
modified: 2026-03-18
tags:
    - attack.defense-impairment
    - attack.t1222.002
logsource:
    product: linux
    category: process_creation
detection:
    selection:
        Image|endswith: '/chmod'
        CommandLine|contains:
            - '/tmp/'
            - '/.Library/'
            - '/etc/'
            - '/opt/'
    filter_main_update_shells:
        CommandLine|contains: 'chmod --reference=/etc/shells'
        ParentCommandLine|endswith: '/update-shells'
    filter_main_postinst:
        CommandLine|contains: '/etc/'
        ParentCommandLine|contains|all:
            - '/var/lib/dpkg/info/'
            - '.postinst configure'
    filter_main_apt_key:
        CommandLine|startswith: 'chmod 700 /tmp/apt-key-gpghome.'
    filter_main_mkinitramfs:
        CommandLine|startswith: 'chmod 755 /var/tmp/mkinitramfs'
    filter_main_landscape:
        CommandLine: 'chmod 0775 /etc/landscape/'
    filter_main_ubuntu_apparmor:
        CommandLine: 'chmod 644 /etc/apparmor.d/tunables/home.d/ubuntu'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Some false positives are to be expected. Apply additional filters as needed before pushing to production.
level: medium

title: Remove Immutable File Attribute
id: 34979410-e4b5-4e5d-8cfb-389fdff05c12
related:
    - id: a5b977d6-8a81-4475-91b9-49dbfcd941f7
      type: derived
status: test
description: Detects usage of the 'chattr' utility to remove immutable file attribute.
references:
    - https://www.trendmicro.com/en_us/research/22/i/how-malicious-actors-abuse-native-linux-tools-in-their-attacks.html
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-15
tags:
    - attack.defense-impairment
    - attack.t1222.002
logsource:
    product: linux
    category: process_creation
detection:
    selection:
        Image|endswith: '/chattr'
        CommandLine|contains: ' -i '
    condition: selection
falsepositives:
    - Administrator interacting with immutable files (e.g. for instance backups).
level: medium

title: Remove Immutable File Attribute - Auditd
id: a5b977d6-8a81-4475-91b9-49dbfcd941f7
status: test
description: Detects removing immutable file attribute.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1222.002/T1222.002.md
author: Jakob Weinzettl, oscd.community
date: 2019-09-23
modified: 2022-11-26
tags:
    - attack.defense-impairment
    - attack.t1222.002
logsource:
    product: linux
    service: auditd
detection:
    selection:
        type: 'EXECVE'
        a0|contains: 'chattr'
        a1|contains: '-i'
    condition: selection
falsepositives:
    - Administrator interacting with immutable files (e.g. for instance backups).
level: medium
simulation:
    - type: atomic-red-team
      name: Remove immutable file attribute
      technique: T1222.002
      atomic_guid: e7469fe2-ad41-4382-8965-99b94dd3c13f

title: File or Folder Permissions Change
id: 74c01ace-0152-4094-8ae2-6fd776dd43e5
status: test
description: Detects file and folder permission changes.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1222.002/T1222.002.md
author: Jakob Weinzettl, oscd.community
date: 2019-09-23
modified: 2021-11-27
tags:
    - attack.defense-impairment
    - attack.t1222.002
logsource:
    product: linux
    service: auditd
detection:
    selection:
        type: 'EXECVE'
        a0|contains:
            - 'chmod'
            - 'chown'
    condition: selection
falsepositives:
    - User interacting with files permissions (normal/daily behaviour).
level: low