Does my PHP File Upload Script open a vulnerability?

[Reed92]

I'm creating a simple upload script so that clients can upload information about potential projects (such as pdf's, cad drawings, etc.) to my server instead of email (the size of these files are sometimes too big for email)

Here's what I have:

Client Side

<form enctype="multipart/form-data" action="script.php" method="POST">
<input type="hidden" name="MAX_FILE_SIZE" value="10000000" />
<ul>
<li class="form"><label for="variable">Choose a file to upload: </label></li>
<li class="form"><input name="variable" type="file" /><br /></li>
<li class="form"><input type="submit" value="Upload File" /></li>
</ul>
</form>

Server Side

<?php
$uploaddir = './upload/'; // Relative path under webroot
$uploadfile = $uploaddir . basename($_FILES['variable']['name']);
if (move_uploaded_file($_FILES['variable']['tmp_name'], $uploadfile)) {
echo "<p>File uploaded successfully</p>";
} else {
echo "<p>File uploading failed.  Please use your browser's back button to return to the upload form.</p>";
}
?>

Now, of course this would be normally vulnerable. It looks to me, though, that I can set my upload folder permissions to 700 and be safe.

Am I wrong thinking this way? Is it possible that the server will somehow execute a file automatically? (Because I don't see a way that this could cause harm)

 

[DHDdirect]

You will want to compare file extensions to limit the type of files to be uploaded. You could also limit the uploaders to only registered users, size limits, only certain file names etc.

 

[Reed92]

You will want to compare file extensions to limit the type of files to be uploaded. You could also limit the uploaders to only registered users, size limits, only certain file names etc.

Alright, thanks. I know that is generally what is done. There is not much of value on the server, so I'm not too concerned.


However, I would still like to know how someone could gain access using the field. Perhaps this question is more suited for a dedicated php forum.