Need 3 things to write files to db
- User with FILE privilege enabled
- MySQL global secure_file_priv variable not enabled
3. Write access to the location we want to write to on the back-end server
with union
if null -> we can r/w everywhere.
webshell usen
immer shell.php?0=cat /etc/passwd
528d6d9cedc2c7aab146ef226e918396