PHP LD_PRELOAD Payload. A tool to bypass disable_functions.
PHP in Linux calls a binary (sendmail) when the mail() function is executed. If we have putenv() allowed, we can set the environment variable "LD_PRELOAD", so we can preload an arbitrary shared object. Our shared object will execute our custom payload (a binary or a bash script) without the PHP restrictions, so we can have a reverse shell, for example.
run exploit.php and connect using gsocket client
this design chosen to keep everything in a single file of php script to prevent issue with the firewall when downloading elf data from external source nonexistent download function