Windows: Local user account creation via net.exe or net1.exe

Alerts on net.exe/net1.exe launching with "user" and "add" to create local accounts on Windows.

FreeUnreviewedSigmamediumv1

windows-local-user-account-creation-via-net-exe-or-net1-exe-cd219ff3

title: "Windows: Local user account creation via net.exe or net1.exe"
id: 7b6cb08c-0bca-4835-a9f4-fa0286cdc78b
related:
  - id: b9f0e6f5-09b4-4358-bae4-08408705bd5c
    type: similar
  - id: cd219ff3-fa99-45d4-8380-a7d15116c6dc
    type: derived
status: test
description: This rule flags process executions where net.exe or net1.exe is launched with command-line arguments containing both "user" and "add", indicating local user creation attempts. Attackers may use this technique to establish persistence by adding new accounts. It relies on Windows process creation telemetry, including the image path and command line content.
references:
  - https://eqllib.readthedocs.io/en/latest/analytics/014c3f51-89c6-40f1-ac9c-5688f26090ab.html
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1136.001/T1136.001.md
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_net_user_add.yml
author: Endgame, JHasenbusch (adapted to Sigma for oscd.community), Huntrule Team
date: 2018-10-30
modified: 2023-02-21
tags:
  - attack.persistence
  - attack.t1136.001
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith:
        - \net.exe
        - \net1.exe
    - OriginalFileName:
        - net.exe
        - net1.exe
  selection_cli:
    CommandLine|contains|all:
      - user
      - add
  condition: all of selection_*
falsepositives:
  - Legitimate user creation.
  - Better use event IDs for user creation rather than command line rules.
level: medium
license: DRL-1.1

What it detects

This rule flags process executions where net.exe or net1.exe is launched with command-line arguments containing both "user" and "add", indicating local user creation attempts. Attackers may use this technique to establish persistence by adding new accounts. It relies on Windows process creation telemetry, including the image path and command line content.

Known false positives

Legitimate user creation.
Better use event IDs for user creation rather than command line rules.

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.