Suspicious Invocation of Shell via AWK - Linux

detection:
  selection_cli:
    CommandLine|contains:
      - '/bin/bash'
      - '/bin/dash'
      - '/bin/fish'
      - '/bin/sh'
      - '/bin/zsh'
  selection_img:
    CommandLine|contains: 'BEGIN {system'
    Image|endswith:
      - '/awk'
      - '/gawk'
      - '/mawk'
      - '/nawk'
  condition: all of selection_*

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Li Ling, Andy Parkidomo, Robert Rakowski, Blake Hartstein (Bloomberg L.P.), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

The commands documented for awk, gawk, mawk, nawk trip it: each is on its program’s page, read by CmdID.