Local Groups Discovery Attempt - Linux

A Sigma rule for process creation on Linux, by Ömer Günal, Alejandro Ortuno, oscd.community.

low 1 ATT&CK technique 13 programs it names 4 everyday examples trip it

What it looks for

its detection, as SigmaHQ writes it

detection:
  selection_getent:
    CommandLine|contains:
      - ' group'
      - ' gshadow'
    Image|endswith: '/getent'
  selection_groups:
    Image|endswith: '/groups'
  selection_read_utilities:
    CommandLine|contains:
      - 'group'
      - 'gshadow'
    Image|endswith:
      - '/cat'
      - '/ed'
      - '/emacs'
      - '/head'
      - '/less'
      - '/makemap'
      - '/more'
      - '/nano'
      - '/sqlite3'
      - '/tail'
      - '/vi'
      - '/vim'
  selection_ypcat:
    CommandLine|contains: 'group'
    Image|endswith: '/ypcat'
  condition: 1 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 Ömer Günal, Alejandro Ortuno, oscd.community, 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.

Command lines that trip it

everyday examples from tldr-pages, CC BY 4.0, each read by CmdID

Get list of all groups on the page for getent

getent groupIdentify

See the members of a group on the page for getent

getent group group_nameIdentify

Print group memberships for the current user on the page for groups

groupsIdentify

Print group memberships for a list of users on the page for groups

groups username1 username2 ...Identify

Programs and files it names

their pages here

catedemacsgetentheadlessmorenanosqlite3tailvivimgroups

ATT&CK

the techniques it is tagged with

T1069.001Permission Groups Discovery: Local Groups

Local Groups Discovery Attempt - Linux

What it looks for

Command lines that trip it

Programs and files it names

ATT&CK

Other rules for T1069.001 Permission Groups Discovery: Local Groups