Linux Shell Pipe to Shell — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: medium. Source dates: 2022-03-14 / 2022-07-26.

{
  "product": "linux",
  "category": "process_creation"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 17d916982510283f336fd2d98bb8d2f81bbdfcdbbcaaf5abb26fbd4c9193eaad

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

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.stealth
    - 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

Original YAML and metadata in JSON

False positives

• Legitimate software that uses these patterns

Source references

• Internal Research (source note; no public URL supplied)