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I am creating a social network and I want to know if this is a secure way of uploading pics/gifs and videos.

if(isset($_POST['post'])) {

    $uploadOk = 1;
    $imageName = $_FILES['postToUpload']['name'];
    $errorMessage = "";
    $picdate = date('Y-m-d_H-i-s');

    if($imageName != "") {
        $targetDir = "assets/images/posts/";
        $imageName = $targetDir . uniqid() . basename($imageName);
        $imageFileType = pathinfo($imageName, PATHINFO_EXTENSION);
        
        if($_FILES['postToUpload']['size'] > 10971520) {
            $errorMessage = "Your file is to large";
            $uploadOk = 0;
        }

        if (strtolower($imageFileType) != "jpeg" && strtolower($imageFileType) != "png" &&
            strtolower($imageFileType) != "jpg" && strtolower($imageFileType) != "gif"
            && strtolower($imageFileType) != "mp4"&& strtolower($imageFileType) != "Ogg"
            && strtolower($imageFileType) != "WebM"){

            $errorMessage = "File type not allowed.";
            $uploadOk = 0;
        }

        if($uploadOk){
            if(move_uploaded_file($_FILES['postToUpload']['tmp_name'], $imageName)) {
                // image uploaded

            } else{
                // image did not upload
                $uploadOk = 0;
            }
        }
    }

    if($uploadOk) {

    $post = new Post($con, $userLoggedIn);

    $post->submitPost(trim(strip_tags(filter_var($_POST['post_text'], FILTER_SANITIZE_STRING))), 
        'none', $imageName);

    } else {

        echo "<div class='alert alert-danger'>
                $errorMessage
            </div>";
    }
}
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2
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Your code is insecure because:

  • It only relies on the file extension, so attackers can upload any backdoors.
  • It accesses variable $_FILES['postToUpload']['name'] without checking if it is defined and this may lead to Full Path Disclosure.
  • It uses function uniqid() without any arguments, so uniqueness is not guaranteed and the files that are uploaded simultaneously and have the same file name will be overwritten.
  • It stores the filename provided by user without removing potentially dangerous characters and this may lead to unexpected results.

Some recommendations to improve your code:

  • Get rid of the $uploadOk variable. You already have and handle the $errorMessage variable and this is enough to check if the file was uploaded successfully.
  • You should define $imageFileType as lowercase, instead of calling strtolower() for each extension.
  • You should define all accepted file extensions as lowercase, otherwise users won't able to upload some files (in your case WebM and Ogg, because strtolower($imageFileType) != "Ogg" and strtolower($imageFileType) != "WebM" will always be FALSE).
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