title: Linux Recon Indicators
id: 0cf7a157-8879-41a2-8f55-388dd23746b7
status: test
description: Detects events with patterns found in commands used for reconnaissance on linux systems
references:
    - https://github.com/sleventyeleven/linuxprivchecker/blob/0d701080bbf92efd464e97d71a70f97c6f2cd658/linuxprivchecker.py
author: Florian Roth (Nextron Systems)
date: 2022-06-20
tags:
    - attack.reconnaissance
    - attack.t1592.004
    - attack.credential-access
    - attack.t1552.001
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        CommandLine|contains:
            - ' -name .htpasswd'
            - ' -perm -4000 '
    condition: selection
falsepositives:
    - Legitimate administration activities
level: high

title: Access of Sudoers File Content
id: 0f79c4d2-4e1f-4683-9c36-b5469a665e06
status: test
description: Detects the execution of a text-based file access or inspection utilities to read the content of /etc/sudoers in order to potentially list all users that have sudo rights.
references:
    - https://github.com/sleventyeleven/linuxprivchecker/
author: Florian Roth (Nextron Systems)
date: 2022-06-20
modified: 2025-06-04
tags:
    - attack.reconnaissance
    - attack.t1592.004
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith:
            - '/cat'
            - '/ed'
            - '/egrep'
            - '/emacs'
            - '/fgrep'
            - '/grep'
            - '/head'
            - '/less'
            - '/more'
            - '/nano'
            - '/tail'
        CommandLine|contains: ' /etc/sudoers'
    condition: selection
falsepositives:
    - Legitimate administration activities
level: medium

title: Print History File Contents
id: d7821ff1-4527-4e33-9f84-d0d57fa2fb66
status: test
description: Detects events in which someone prints the contents of history files to the commandline or redirects it to a file for reconnaissance
references:
    - https://github.com/sleventyeleven/linuxprivchecker/
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1552.003/T1552.003.md
author: Florian Roth (Nextron Systems)
date: 2022-06-20
modified: 2022-09-15
tags:
    - attack.reconnaissance
    - attack.t1592.004
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith:
            - '/cat'
            - '/head'
            - '/tail'
            - '/more'
    selection_history:
        - CommandLine|contains:
              - '/.bash_history'
              - '/.zsh_history'
        - CommandLine|endswith:
              - '_history'
              - '.history'
              - 'zhistory'
    condition: all of selection*
falsepositives:
    - Legitimate administration activities
level: medium