Suspicious Invocation of Shell via AWK - Linux — Sigma Rule

Rule metadata and linked tags

Author: Li Ling, Andy Parkidomo, Robert Rakowski, Blake Hartstein (Bloomberg L.P.). Source status: test; severity: high. Source dates: 2024-09-02 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: e79ec9f19754454997835bf43ca0a28274a5eb9c51642ca54eadaceb292cb32c

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: Suspicious Invocation of Shell via AWK - Linux
id: 8c1a5675-cb85-452f-a298-b01b22a51856
status: test
description: |
    Detects the execution of "awk" or it's sibling commands, to invoke a shell using the system() function.
    This behavior is commonly associated with attempts to execute arbitrary commands or escalate privileges, potentially leading to unauthorized access or further exploitation.
references:
    - https://gtfobins.github.io/gtfobins/awk/#shell
    - https://gtfobins.github.io/gtfobins/gawk/#shell
    - https://gtfobins.github.io/gtfobins/nawk/#shell
    - https://gtfobins.github.io/gtfobins/mawk/#shell
author: Li Ling, Andy Parkidomo, Robert Rakowski, Blake Hartstein (Bloomberg L.P.)
date: 2024-09-02
tags:
    - attack.execution
    - attack.t1059
logsource:
    category: process_creation
    product: linux
detection:
    selection_img:
        Image|endswith:
            - '/awk'
            - '/gawk'
            - '/mawk'
            - '/nawk'
        CommandLine|contains: 'BEGIN {system'
    selection_cli:
        CommandLine|contains:
            - '/bin/bash'
            - '/bin/dash'
            - '/bin/fish'
            - '/bin/sh'
            - '/bin/zsh'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://gtfobins.github.io/gtfobins/awk/#shell
• https://gtfobins.github.io/gtfobins/gawk/#shell
• https://gtfobins.github.io/gtfobins/nawk/#shell
• https://gtfobins.github.io/gtfobins/mawk/#shell