sigmamediumHunting

Linux Shell Pipe to Shell

Detects suspicious process command line that starts with a shell that executes something and finally gets piped into another shell

MITRE ATT&CK

T1140

defense-evasion

Detection Query

selection:
  CommandLine|startswith:
    - "sh -c "
    - "bash -c "
selection_exec:
  - CommandLine|contains:
      - "| bash "
      - "| sh "
      - "|bash "
      - "|sh "
  - CommandLine|endswith:
      - "| bash"
      - "| sh"
      - "|bash"
      - " |sh"
condition: all of selection*

Author

Florian Roth (Nextron Systems)

Created

2022-03-14

Data Sources

linuxProcess Creation Events

Platforms

linux

References

Internal Research

Tags

attack.defense-evasionattack.t1140

Raw Content

title: Linux Shell Pipe to Shell
id: 880973f3-9708-491c-a77b-2a35a1921158
status: test
description: Detects suspicious process command line that starts with a shell that executes something and finally gets piped into another shell
references:
    - Internal Research
author: Florian Roth (Nextron Systems)
date: 2022-03-14
modified: 2022-07-26
tags:
    - attack.defense-evasion
    - attack.t1140
logsource:
    product: linux
    category: process_creation
detection:
    selection:
        CommandLine|startswith:
            - 'sh -c '
            - 'bash -c '
    selection_exec:
        - CommandLine|contains:
              - '| bash '
              - '| sh '
              - '|bash '
              - '|sh '
        - CommandLine|endswith:
              - '| bash'
              - '| sh'
              - '|bash'
              - ' |sh'
    condition: all of selection*
falsepositives:
    - Legitimate software that uses these patterns
level: medium