NetcatPHPShell is a PHP backdoor that can be leveraged to launch a connect-back shell.
You can download it from the following link: https://packetstormsecurity.com/files/download/112491/NetcatPHPShell-1.10.zip
Source: https://packetstormsecurity.com/files/112491/NetcatPHPShell-1.10.html