rexd
The rexd service and the on client program provide remote command execution on
a network. It allows remote users to run RPC programs on a host. To the extent
that it is possible, the complete client environment, including working
directory and environment variables, is made available on the remote system.
By default, the rexd server believes everything that the client sends it. It
is highly insecure because it can be used to run an arbitrary shell on the host.
An attacker can exploit the service and execute commands as almost any user.
The standard rexd server has no provision for access control, nor does it
require that the client use a privileged network port.