【原创】记一次ctf实战—— 0CTF-2016-Web-piapiapia（失败）

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2022年12月3日16:40:29评论42 views字数 9085阅读30分17秒阅读模式

[huayang]

【原创】记一次ctf实战—— 0CTF-2016-Web-piapiapia（失败）

老样子，进去看看

看看有没有注入

这提示看着就不像有过滤的，会不会像那次做的那题一样是泄露呢BDJCTF-2020-Web-easy_search

扫一下子域名

哇，貌似有好东西

下载看看

先贴出代码

class.php

<?php
require('config.php');
class user extends mysql{
	private $table = 'users';
	public function is_exists($username) {
		$username = parent::filter($username);
		$where = "username = '$username'";
		return parent::select($this->table, $where);
	}
	public function register($username, $password) {
		$username = parent::filter($username);
		$password = parent::filter($password);
		$key_list = Array('username', 'password');
		$value_list = Array($username, md5($password));
		return parent::insert($this->table, $key_list, $value_list);
	}
	public function login($username, $password) {
		$username = parent::filter($username);
		$password = parent::filter($password);
		$where = "username = '$username'";
		$object = parent::select($this->table, $where);
		if ($object && $object->password === md5($password)) {
			return true;
		} else {
			return false;
		}
	}
	public function show_profile($username) {
		$username = parent::filter($username);
		$where = "username = '$username'";
		$object = parent::select($this->table, $where);
		return $object->profile;
	}
	public function update_profile($username, $new_profile) {
		$username = parent::filter($username);
		$new_profile = parent::filter($new_profile);
		$where = "username = '$username'";
		return parent::update($this->table, 'profile', $new_profile, $where);
	}
	public function __tostring() {
		return __class__;
	}
}
class mysql {
	private $link = null;
	public function connect($config) {
		$this->link = mysql_connect(
			$config['hostname'],
			$config['username'],
			$config['password']
		);
		mysql_select_db($config['database']);
		mysql_query("SET sql_mode='strict_all_tables'");
		return $this->link;
	}
	public function select($table, $where, $ret = '*') {
		$sql = "SELECT $ret FROM $table WHERE $where";
		$result = mysql_query($sql, $this->link);
		return mysql_fetch_object($result);
	}
	public function insert($table, $key_list, $value_list) {
		$key = implode(',', $key_list);
		$value = '\'' . implode('\',\'', $value_list) . '\'';
		$sql = "INSERT INTO $table ($key) VALUES ($value)";
		return mysql_query($sql);
	}
	public function update($table, $key, $value, $where) {
		$sql = "UPDATE $table SET $key = '$value' WHERE $where";
		return mysql_query($sql);
	}
	public function filter($string) {
		$escape = array('\'', '\\\\');
		$escape = '/' . implode('|', $escape) . '/';
		$string = preg_replace($escape, '_', $string);
		$safe = array('select', 'insert', 'update', 'delete', 'where');
		$safe = '/' . implode('|', $safe) . '/i';
		return preg_replace($safe, 'hacker', $string);
	}
	public function __tostring() {
		return __class__;
	}
}
session_start();
$user = new user();
$user->connect($config);

config.php

<?php
	$config['hostname'] = '127.0.0.1';
	$config['username'] = 'root';
	$config['password'] = '';
	$config['database'] = '';
	$flag = '';
?>

index.php

<?php
	require_once('class.php');
	if($_SESSION['username']) {
		header('Location: profile.php');
		exit;
	}
	if($_POST['username'] && $_POST['password']) {
		$username = $_POST['username'];
		$password = $_POST['password'];
		if(strlen($username) < 3 or strlen($username) > 16)
			die('Invalid user name');
		if(strlen($password) < 3 or strlen($password) > 16)
			die('Invalid password');
		if($user->login($username, $password)) {
			$_SESSION['username'] = $username;
			header('Location: profile.php');
			exit;
		}
		else {
			die('Invalid user name or password');
		}
	}
	else {
?>
<!DOCTYPE html>
<html>
<head>
   <title>Login</title>
   <link href="static/bootstrap.min.css" rel="stylesheet">
   <script srcb64="static/jquery.min.js"></script>
   <script srcb64="static/bootstrap.min.js"></script>
</head>
<body>
	<div class="container" style="margin-top:100px">
		<form action="index.php" method="post" class="well" style="width:220px;margin:0px auto;">
			<img srcb64="static/piapiapia.gif" class="img-memeda " style="width:180px;margin:0px auto;">
			<h3>Login</h3>
			<label>Username:</label>
			<input type="text" name="username" style="height:30px"class="span3"/>
			<label>Password:</label>
			<input type="password" name="password" style="height:30px" class="span3">
			<button type="submit" class="btn btn-primary">LOGIN</button>
		</form>
	</div>
</body>
</html>
<?php
	}
?>

profile.php

<?php
	require_once('class.php');
	if($_SESSION['username'] == null) {
		die('Login First');
	}
	$username = $_SESSION['username'];
	$profile=$user->show_profile($username);
	if($profile  == null) {
		header('Location: update.php');
	}
	else {
		$profile = unserialize($profile);
		$phone = $profile['phone'];
		$email = $profile['email'];
		$nickname = $profile['nickname'];
		$photo = base64_encode(file_get_contents($profile['photo']));
?>
<!DOCTYPE html>
<html>
<head>
   <title>Profile</title>
   <link href="static/bootstrap.min.css" rel="stylesheet">
   <script srcb64="static/jquery.min.js"></script>
   <script srcb64="static/bootstrap.min.js"></script>
</head>
<body>
	<div class="container" style="margin-top:100px">
		<img srcb64="data:image/gif;base64,<?php echo $photo; ?>" class="img-memeda " style="width:180px;margin:0px auto;">
		<h3>Hi <?php echo $nickname;?></h3>
		<label>Phone: <?php echo $phone;?></label>
		<label>Email: <?php echo $email;?></label>
	</div>
</body>
</html>
<?php
	}
?>

register.php

<?php
	require_once('class.php');
	if($_POST['username'] && $_POST['password']) {
		$username = $_POST['username'];
		$password = $_POST['password'];
		if(strlen($username) < 3 or strlen($username) > 16)
			die('Invalid user name');
		if(strlen($password) < 3 or strlen($password) > 16)
			die('Invalid password');
		if(!$user->is_exists($username)) {
			$user->register($username, $password);
			echo 'Register OK!<a href="index.php">Please Login</a>';
		}
		else {
			die('User name Already Exists');
		}
	}
	else {
?>
<!DOCTYPE html>
<html>
<head>
   <title>Login</title>
   <link href="static/bootstrap.min.css" rel="stylesheet">
   <script srcb64="static/jquery.min.js"></script>
   <script srcb64="static/bootstrap.min.js"></script>
</head>
<body>
	<div class="container" style="margin-top:100px">
		<form action="register.php" method="post" class="well" style="width:220px;margin:0px auto;">
			<img srcb64="static/piapiapia.gif" class="img-memeda " style="width:180px;margin:0px auto;">
			<h3>Register</h3>
			<label>Username:</label>
			<input type="text" name="username" style="height:30px"class="span3"/>
			<label>Password:</label>
			<input type="password" name="password" style="height:30px" class="span3">
			<button type="submit" class="btn btn-primary">REGISTER</button>
		</form>
	</div>
</body>
</html>
<?php
	}
?>

update.php

<?php
	require_once('class.php');
	if($_SESSION['username'] == null) {
		die('Login First');
	}
	if($_POST['phone'] && $_POST['email'] && $_POST['nickname'] && $_FILES['photo']) {
		$username = $_SESSION['username'];
		if(!preg_match('/^\d{11}$/', $_POST['phone']))
			die('Invalid phone');
		if(!preg_match('/^[_a-zA-Z0-9]{1,10}@[_a-zA-Z0-9]{1,10}\.[_a-zA-Z0-9]{1,10}$/', $_POST['email']))
			die('Invalid email');
		if(preg_match('/[^a-zA-Z0-9_]/', $_POST['nickname']) || strlen($_POST['nickname']) > 10)
			die('Invalid nickname');
		$file = $_FILES['photo'];
		if($file['size'] < 5 or $file['size'] > 1000000)
			die('Photo size error');
		move_uploaded_file($file['tmp_name'], 'upload/' . md5($file['name']));
		$profile['phone'] = $_POST['phone'];
		$profile['email'] = $_POST['email'];
		$profile['nickname'] = $_POST['nickname'];
		$profile['photo'] = 'upload/' . md5($file['name']);
		$user->update_profile($username, serialize($profile));
		echo 'Update Profile Success!<a href="profile.php">Your Profile</a>';
	}
	else {
?>
<!DOCTYPE html>
<html>
<head>
   <title>UPDATE</title>
   <link href="static/bootstrap.min.css" rel="stylesheet">
   <script srcb64="static/jquery.min.js"></script>
   <script srcb64="static/bootstrap.min.js"></script>
</head>
<body>
	<div class="container" style="margin-top:100px">
		<form action="update.php" method="post" enctype="multipart/form-data" class="well" style="width:220px;margin:0px auto;">
			<img srcb64="static/piapiapia.gif" class="img-memeda " style="width:180px;margin:0px auto;">
			<h3>Please Update Your Profile</h3>
			<label>Phone:</label>
			<input type="text" name="phone" style="height:30px"class="span3"/>
			<label>Email:</label>
			<input type="text" name="email" style="height:30px"class="span3"/>
			<label>Nickname:</label>
			<input type="text" name="nickname" style="height:30px" class="span3">
			<label for="file">Photo:</label>
			<input type="file" name="photo" style="height:30px"class="span3"/>
			<button type="submit" class="btn btn-primary">UPDATE</button>
		</form>
	</div>
</body>
</html>
<?php
	}
?>

简单的审计一下理个大概的思路

这题的代码量大大超乎了预计

update.php有个序列化

profile.php有反序列化

可能是我们解题的关键

我们看见一个很重要的文件register.php，从中可知是注册页面

并且所有文件都指向class.php，而class.php又指向config.php

由此可知我们要的flag在加载完成后的config.php里

登录完成后我们看见如上页面

咦Nickname是个什么东西，去源码看看

发现新大陆

要绕过就必须要这里为false

成功之后即可跳转到profile.php页面

这个页面是我们填写完信息展示的页面我们发现了这边就是读取数据库中的信息之后反序列化将值一一对应

但是对图片进行了file_get_contents() 之后又进行了 base64加密这里我们关键是发现了file_contents()这个函数

结合上面发现的config.php 我们现在只要想办法让它（$photo）可控读取config.php即可得到flag

所以就要用到反序列化长度逃逸

既然先把变量序列化，然后进行过滤，在过滤的过程中把某个关键词替换成了长度更长的关键词，导致长度加长，最终引起逃逸

我们看到class.php文件

我们只有传入的字符串中有’where’关键字，被替换为’hacker’关键字，才会让长度加一，否则长度不变

上面我们说到了（$photo）可控读取config.php

而

所以我们要将其序列化

<?php
$a = 'photo';
$b = 'config.php';
echo serialize($a);
echo serialize($b);

为什么多了个} 因为要闭合后面的where

因为”;}s:5:“photo”;s:10:“config.php”;}的长度为34

我们要把这34的长度给逃逸出来，由上可只需要34个where

34个where转换为hacker刚好多出34个长度

payload

wherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewhere";}s:5:"photo";s:10:"config.php";}

注意一下phone和email的格式等下懒得重新搞

抓包把nickname改为数组，就是添加一个[]

放包进去即可看见flag

参考文章：
https://www.jianshu.com/p/3b44e72444c1
https://www.cnblogs.com/xhds/p/12393686.html
https://blog.csdn.net/qq_43622442/article/details/105751356
https://blog.csdn.net/crisprx/article/details/104705018/
https://blog.csdn.net/zz_Caleb/article/details/96777110
http://www.mamicode.com/info-detail-2903729.html
http://yqxiaojunjie.com/index.php/archives/171/

[/huayang]

FROM：浅浅淡淡[hellohy]

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