PostgreSQL COPY FROM PROGRAM Command Execution

Installations running Postgres 9.3 and above have functionality which allows for the superuser
and users with 'pg_execute_server_program' to pipe to and from an external program using COPY.
This allows arbitrary command execution as though you have console access.

This module attempts to create a new table, then execute system commands in the context of
copying the command output into the table.

This module should work on all Postgres systems running version 9.3 and above.

For Linux & OSX systems, target 1 is used with cmd payloads such as: cmd/unix/reverse_perl

For Windows Systems, target 2 is used with powershell payloads such as: cmd/windows/powershell_reverse_tcp
Alternativly target 3 can be used to execute generic commands, such as a web_delivery meterpreter powershell payload
or other customised command.