Desde la página del manual:
-e command, --exec command (Execute command) .
Execute the specified command after a connection has been established. The command must
be specified as a full pathname. All input from the remote client will be sent to the
application and responses sent back to the remote client over the socket, thus making
your command-line application interactive over a socket. Combined with --keep-open,
Ncat will handle multiple simultaneous connections to your specified port/application
like inetd. Ncat will only accept a maximum, definable, number of simultaneous
connections controlled by the -m option. By default this is set to 100 (60 on Windows).
Simplemente ejecuta /bin/bash <command> <params>
en el host remoto. No se transfiere ningún ejecutable, pero solo se ejecutan los ejecutables locales.