using this google search , you can find the vulnerable Sites.
If you want to find the vulnerability in your web application, use this google dark:
After you search in google; if you find any page ends with “simple-upload-53.php” , follow the link.
Now you can see the upload option in the site. Here is the biggest problem, it allows anyone to upload files.
An attacker can upload Backdoor shell as “.php.jpg” or “.php.gif” etc.
The uploaded shell will be in this place:
After uploading the shell , an attacker can deface your site. So better check whether your site also has this vulnerability or not.
“Prevention is better than Cure”.