Low
后端代码没有对上传的文件做任何过滤，所以可以上传一句话木马。
php
<?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>";
}
}
?>在PHP中，$_FILES 是一个全局数组，用于处理通过HTML表单上传的文件。每个上传的文件在 $_FILES 数组中都有自己的子数组，包含文件的各种信息。
php
$_FILES 各项属性的详细说明
$_FILES['uploaded']['name']:上传文件的原始名称。
$_FILES['uploaded']['type']:上传文件的MIME类型（如 image/jpeg），由浏览器提供。
$_FILES['uploaded']['tmp_name']:上传文件在服务器上的临时文件路径。
$_FILES['uploaded']['error']:上传过程中可能发生的错误代码。
常见的错误代码：
UPLOAD_ERR_OK (0): 没有错误，文件上传成功。
UPLOAD_ERR_INI_SIZE (1): 上传文件超过了 php.ini 中 upload_max_filesize 选项限制的值。
UPLOAD_ERR_FORM_SIZE (2): 上传文件超过了HTML表单中 MAX_FILE_SIZE 选项指定的值。
UPLOAD_ERR_PARTIAL (3): 文件只有部分被上传。
UPLOAD_ERR_NO_FILE (4): 没有文件被上传。
UPLOAD_ERR_NO_TMP_DIR (6): 找不到临时文件夹。
UPLOAD_ERR_CANT_WRITE (7): 文件写入失败。
UPLOAD_ERR_EXTENSION (8): 文件上传被PHP扩展程序中断。
$_FILES['uploaded']['size']:上传文件的大小，以字节为单位。Medium
观察后端代码，对上传文件的MIME类型，大小进行了限制。
php
<?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>';
}
}
?>我们可以通过burp抓包之后，修改对应参数进行绕过
上传成功
High
观察后端代码，对上传文件的后缀，文件头进行了过滤。
php
<?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>';
}
}
?>文件头绕过记录两种方法
1.把shell.php和一张图片放在一起，执行copy命令，如图
2.用十六进制软件直接在文件开头加上文固定内容的文件头
之后直接上传
上传之后都结合文件包含漏洞High Level执行DVWA-File Inclusion（因为要将png后缀图片按php文件解析）
上传之后用蚁剑连接，直接连接是显示不成功，是因为没有cookie。
之后浏览网站，进入网站修改难度为high（因为DVWA默认难度为impossible难度没法绕过）并保存cookie。
Impossible
观察后端源码发现，对文件内容进行了严格地检查，对文件进行重命名，文件大小后缀都进行了限制，同时加入token。
php
<?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();
?>