name: Linux Add User Account
id: 51fbcaf2-6259-11ec-b0f3-acde48001122
version: 1
date: '2021-12-21'
author: Teoderick Contreras, Splunk
status: production
type: Hunting
description: This analytic looks for commands to create user accounts on the linux
  platform. This technique is commonly abuse by adversaries, malware author and red
  teamers to persist on the targeted or compromised host by creating new user with
  an elevated privilege. This Hunting query may catch normal creation of user by administrator
  so filter is needed.
data_source:
- Sysmon Event ID 1
search:
  selection1:
    CommandLine:
    - '*useradd *'
    - '*adduser *'
  selection2:
    Image|endswith:
    - useradd
    - adduser
  condition: selection1 or selection2
how_to_implement: To successfully implement this search, you need to be ingesting
  logs with the process name, parent process, and command-line executions from your
  endpoints. If you are using Sysmon, you can use the Add-on for Linux Sysmon from
  Splunkbase.
known_false_positives: Administrator or network operator can execute this command.
  Please update the filter macros to remove false positives.
references:
- https://linuxize.com/post/how-to-create-users-in-linux-using-the-useradd-command/
tags:
  analytic_story:
  - Linux Privilege Escalation
  - Linux Persistence Techniques
  asset_type: Endpoint
  confidence: 50
  impact: 50
  message: A commandline $process$ that may create user account on $dest$
  mitre_attack_id:
  - T1136.001
  - T1136
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  risk_score: 25
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1548.003/linux_adduser/sysmon_linux.log
    source: Syslog:Linux-Sysmon/Operational
    sourcetype: sysmon:linux