Taint
php extension used to detect XSS codes(tainted string), And also can be used to spot sql injection vulnerabilities, shell inject, etc.
The idea is from https://wiki.php.net/rfc/taint, I implemented it in a php extension which make the patch no-needed.
Please note that do not enable this extension in product env, since it will slowdown your app.
Requirement
- PHP-5.2 +
Install
taint is an PECL extension, thus you can simply install it by:
pecl install taint
Compile taint in Linux
$/path/to/phpize
$./configure --with-php-config=/path/to/php-config/
$make && make install
Usage
When taint is enabled, if you pass a tainted string(comes from $_GET, $_POST or $_COOKIE) to some functions, taint will warn you about that.
<?php
$a = trim($_GET['a']);
$file_name = '/tmp' . $a;
$output = "Welcome, {$a} !!!";
$var = "output";
$sql = "Select * from " . $a;
$sql .= "ooxx";
echo $output;
print $$var;
include($file_name);
mysql_query($sql);
The above example will output something similar to:
Warning: main() [function.echo]: Attempt to echo a string that might be tainted
Warning: main() [function.echo]: Attempt to print a string that might be tainted
Warning: include() [function.include]: File path contains data that might be tainted
Warning: mysql_query() [function.mysql-query]: SQL statement contains data that might be tainted
If you need to hide the errors for a particular script, you can:
ini_set('taint.error_level', 0);