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User Has Been Deleted Via Userdel

A Sigma rule for process creation on Linux, by Tuan Le (NCSGroup).

medium 1 ATT&CK technique 1 program it names 3 everyday examples trip it

What it looks for

its detection, as SigmaHQ writes it
detection:
  selection:
    Image|endswith: '/userdel'
  condition: 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 Tuan Le (NCSGroup), 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

Remove a user on the page for userdel

sudo userdel usernameIdentify

Remove a user in other root directory on the page for userdel

sudo userdel --root path/to/other_root usernameIdentify

Remove a user along with the home directory and mail spool on the page for userdel

sudo userdel --remove usernameIdentify

Programs and files it names

their pages here
userdel

ATT&CK

the techniques it is tagged with
T1531Account Access Removal

Other rules for T1531 Account Access Removal

Group Has Been Deleted Via Groupdel