rhymix/common/framework/security.php
Kijin Sung e423cba24d Use Origin header before Referer to check CSRF
OWASP에서는 Referer 헤더보다 Origin 헤더를 먼저 체크하는 것을 권장합니다.
Referer가 비어 있는 경우에도 Origin 헤더에는 유용한 정보가 들어 있을 수 있기 때문입니다.

https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html
2021-02-23 16:51:46 +09:00

415 lines
10 KiB
PHP

<?php
namespace Rhymix\Framework;
/**
* The security class.
*/
class Security
{
/**
* Sanitize a variable.
*
* @param string $input
* @param string $type
* @return string|false
*/
public static function sanitize($input, $type)
{
switch ($type)
{
// Escape HTML special characters.
case 'escape':
if (!utf8_check($input)) return false;
return escape($input);
// Strip all HTML tags.
case 'strip':
if (!utf8_check($input)) return false;
return escape(strip_tags($input));
// Clean up HTML content to prevent XSS attacks.
case 'html':
if (!utf8_check($input)) return false;
return Filters\HTMLFilter::clean($input);
// Clean up the input to be used as a safe filename.
case 'filename':
if (!utf8_check($input)) return false;
return Filters\FilenameFilter::clean($input);
// Unknown filters return false.
default: return false;
}
}
/**
* Encrypt a string using AES.
*
* @param string $plaintext
* @param string $key (optional)
* @param bool $force_compat (optional)
* @return string|false
*/
public static function encrypt($plaintext, $key = null, $force_compat = false)
{
// Get the encryption key.
$key = $key ?: config('crypto.encryption_key');
$key = substr(hash('sha256', $key, true), 0, 16);
// Use defuse/php-encryption if possible.
if (!$force_compat && function_exists('openssl_encrypt'))
{
return base64_encode(\Crypto::Encrypt($plaintext, $key));
}
// Otherwise, use the CryptoCompat class.
if (function_exists('mcrypt_encrypt'))
{
return base64_encode(\CryptoCompat::encrypt($plaintext, $key));
}
else
{
throw new Exception('msg_crypto_not_available');
}
}
/**
* Decrypt a string using AES.
*
* @param string $plaintext
* @param string $key (optional)
* @param bool $force_compat (optional)
* @return string|false
*/
public static function decrypt($ciphertext, $key = null, $force_compat = false)
{
// Get the encryption key.
$key = $key ?: config('crypto.encryption_key');
$key = substr(hash('sha256', $key, true), 0, 16);
// Check whether the ciphertext is valid.
$ciphertext = @base64_decode($ciphertext);
if (strlen($ciphertext) < 48)
{
return false;
}
// Use defuse/php-encryption if possible.
if (!$force_compat && function_exists('openssl_decrypt'))
{
try
{
return \Crypto::Decrypt($ciphertext, $key);
}
catch (\InvalidCiphertextException $e)
{
return false;
}
}
// Otherwise, use the CryptoCompat class.
if (function_exists('mcrypt_decrypt'))
{
return \CryptoCompat::decrypt($ciphertext, $key);
}
else
{
throw new Exception('msg_crypto_not_available');
}
}
/**
* Create a digital signature to verify the authenticity of a string.
*
* @param string $string
* @return string
*/
public static function createSignature($string)
{
$key = config('crypto.authentication_key');
$salt = self::getRandom(8, 'alnum');
$hash = substr(base64_encode(hash_hmac('sha256', hash_hmac('sha256', $string, $salt), $key, true)), 0, 32);
return $salt . strtr($hash, '+/', '-_');
}
/**
* Check whether a signature is valid.
*
* @param string $string
* @param string $signature
* @return bool
*/
public static function verifySignature($string, $signature)
{
if(strlen($signature) !== 40)
{
return false;
}
$key = config('crypto.authentication_key');
$salt = substr($signature, 0, 8);
$hash = substr(base64_encode(hash_hmac('sha256', hash_hmac('sha256', $string, $salt), $key, true)), 0, 32);
return self::compareStrings(substr($signature, 8), strtr($hash, '+/', '-_'));
}
/**
* Generate a cryptographically secure random string.
*
* @param int $length
* @param string $format
* @return string
*/
public static function getRandom($length = 32, $format = 'alnum')
{
// Find out how many bytes of entropy we really need.
switch($format)
{
case 'binary':
$entropy_required_bytes = $length;
break;
case 'hex':
$entropy_required_bytes = ceil($length / 2);
break;
case 'alnum':
case 'printable':
default:
$entropy_required_bytes = ceil($length * 3 / 4);
break;
}
// Cap entropy to 256 bits from any one source, because anything more is meaningless.
$entropy_capped_bytes = min(32, $entropy_required_bytes);
$entropy = false;
// Find and use the most secure way to generate a random string.
if(function_exists('random_bytes'))
{
try
{
$entropy = random_bytes($entropy_capped_bytes);
}
catch (\Exception $e)
{
$entropy = false;
}
}
// Use other good sources of entropy if random_bytes() is not available.
if ($entropy === false)
{
if(function_exists('openssl_random_pseudo_bytes'))
{
$entropy = openssl_random_pseudo_bytes($entropy_capped_bytes);
}
elseif(function_exists('mcrypt_create_iv') && !\RX_WINDOWS)
{
$entropy = mcrypt_create_iv($entropy_capped_bytes, \MCRYPT_DEV_URANDOM);
}
elseif(function_exists('mcrypt_create_iv') && \RX_WINDOWS)
{
$entropy = mcrypt_create_iv($entropy_capped_bytes, \MCRYPT_RAND);
}
elseif(!\RX_WINDOWS && @is_readable('/dev/urandom'))
{
$fp = fopen('/dev/urandom', 'rb');
if (function_exists('stream_set_read_buffer')) // This function does not exist in HHVM.
{
stream_set_read_buffer($fp, 0); // Prevent reading several KB of unnecessary data from urandom.
}
$entropy = fread($fp, $entropy_capped_bytes);
fclose($fp);
}
}
// Use built-in source of entropy if an error occurs while using other functions.
if($entropy === false || strlen($entropy) < $entropy_capped_bytes)
{
$entropy = '';
for($i = 0; $i < $entropy_capped_bytes; $i += 2)
{
$entropy .= pack('S', rand(0, 65536) ^ mt_rand(0, 65535));
}
}
// Mixing (see RFC 4086 section 5)
$output = '';
for($i = 0; $i < $entropy_required_bytes; $i += 32)
{
$output .= hash('sha256', $entropy . $i . rand(), true);
}
// Encode and return the random string.
switch($format)
{
case 'binary':
return substr($output, 0, $length);
case 'printable':
$salt = '';
for($i = 0; $i < $length; $i++)
{
$salt .= chr(33 + (crc32(sha1($i . $output)) % 94));
}
return $salt;
case 'hex':
return substr(bin2hex($output), 0, $length);
case 'alnum':
default:
$salt = substr(base64_encode($output), 0, $length);
$replacements = chr(rand(65, 90)) . chr(rand(97, 122)) . rand(0, 9);
return strtr($salt, '+/=', $replacements);
}
}
/**
* Generate a cryptographically secure random number between $min and $max.
*
* @param int $min
* @param int $max
* @return int
*/
public static function getRandomNumber($min = 0, $max = 0x7fffffff)
{
if (function_exists('random_int'))
{
return random_int($min, $max);
}
else
{
$bytes_required = min(4, ceil(log($max - $min, 2) / 8) + 1);
$bytes = self::getRandom($bytes_required, 'binary');
$offset = abs(hexdec(bin2hex($bytes)) % ($max - $min + 1));
return intval($min + $offset);
}
}
/**
* Generate a random UUID.
*
* @return string
*/
public static function getRandomUUID()
{
$randpool = self::getRandom(16, 'binary');
$randpool[6] = chr(ord($randpool[6]) & 0x0f | 0x40);
$randpool[8] = chr(ord($randpool[8]) & 0x3f | 0x80);
return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($randpool), 4));
}
/**
* Compare two strings in constant time.
*
* @param string $a
* @param string $b
* @return bool
*/
public static function compareStrings($a, $b)
{
if(function_exists('hash_equals'))
{
return hash_equals($a, $b);
}
$diff = strlen($a) ^ strlen($b);
$maxlen = min(strlen($a), strlen($b));
for($i = 0; $i < $maxlen; $i++)
{
$diff |= ord($a[$i]) ^ ord($b[$i]);
}
return $diff === 0;
}
/**
* Check if the current request seems to be a CSRF attack.
*
* This method returns true if the request seems to be innocent,
* and false if it seems to be a CSRF attack.
*
* @param string $referer (optional)
* @return bool
*/
public static function checkCSRF($referer = null)
{
if ($token = $_SERVER['HTTP_X_CSRF_TOKEN'])
{
return Session::verifyToken($token);
}
elseif ($token = $_REQUEST['_rx_csrf_token'])
{
return Session::verifyToken($token);
}
elseif ($_SERVER['REQUEST_METHOD'] === 'GET')
{
return false;
}
else
{
$is_logged = Session::getMemberSrl();
if ($is_logged)
{
trigger_error('CSRF token missing in POST request: ' . (\Context::get('act') ?: '(no act)'), \E_USER_WARNING);
}
if (!$referer)
{
$referer = strval(($_SERVER['HTTP_ORIGIN'] ?? '') ?: ($_SERVER['HTTP_REFERER'] ?? ''));
}
if ($referer !== '' && $referer !== 'null' && (!config('security.check_csrf_token') || !$is_logged))
{
return URL::isInternalURL($referer);
}
else
{
return false;
}
}
}
/**
* Check if the current request seems to be an XXE (XML external entity) attack.
*
* This method returns true if the request seems to be innocent,
* and false if it seems to be an XXE attack.
* This is the opposite of XE's Security::detectingXEE() method.
* The name has also been changed to the more accurate acronym XXE.
*
* @param string $xml (optional)
* @return bool
*/
public static function checkXXE($xml = null)
{
// Stop if there is no XML content.
if (!$xml)
{
return true;
}
// Reject entity tags.
if (strpos($xml, '<!ENTITY') !== false)
{
return false;
}
// Check if there is no content after the xml tag.
$header = preg_replace('/<\?xml.*?\?'.'>/s', '', substr($xml, 0, 100), 1);
if (($xml = trim(substr_replace($xml, $header, 0, 100))) === '')
{
return false;
}
// Check if there is no content after the DTD.
$header = preg_replace('/^<!DOCTYPE[^>]*+>/i', '', substr($xml, 0, 200), 1);
if (($xml = trim(substr_replace($xml, $header, 0, 200))) === '')
{
return false;
}
// Check that the root tag is valid.
if (!preg_match('/^<(methodCall|methodResponse|fault)/', $xml))
{
return false;
}
return true;
}
}