环境：PHP
描述：请问有如何检测图片上传漏洞是否存在？以及如何修补？谢谢！
0x03 无解的防护-全方面限制
当然安全只是相对的，没有绝对的安全，一下代码对输入的文件进行了多种方式的审查并进行了重新编码，是目前比较完善了安全防御措施。
源代码 upload_2.php
<?php
if( isset( $_POST[ 'Upload' ] ) ) {
// 检查token
checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );
$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' ];
$target_path = 'uploads/';
$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;
//判断是否是一张图片
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 ) ) {
//重新制作一张图片，抹去任何可能有危害的数据
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 );
//文件转储
if( rename( $temp_file, ( getcwd() . DIRECTORY_SEPARATOR . $target_path . $target_file ) ) ) {
$html .= "<pre><a href='${target_path}${target_file}'>${target_file}</a> succesfully uploaded!</pre>";
}
else {
$html .= '<pre>Your image was not uploaded.</pre>';
}
//删除所有暂时文件
if( file_exists( $temp_file ) )
unlink( $temp_file );
}
else {
//无效文件
$html .= '<pre>Your image was not uploaded. We can only accept JPEG or PNG images.</pre>';
}
}
// 添加抗csrf验证
generateSessionToken();
?>上述代码的安全措施：