Sure, but you can only move up a stack which exists.
Given that there should be no applications on the other end of the
RS232 apart from the CAD/CAM control program (one would hope, this
would be considered 'normal'), the only hackable device should be that
program. It's not unlikely that the program in question could be set
to perform destructive actions; allot of industrial software of this
type is not well written and buffers certainly don't always get
checked. This would require a custom hack though, I don't know of any
viri which carry protocol definitions for RS232 CAD/CAM programs.
"There aught to be limits to freedom!" George Bush
Not to defend the guy, he makes allot of stupid comments and
decisions, however he is talking about laws and he is not wrong, there
are many people in the world who need certain freedoms removed. How
about they learn to remove the freedom of gun ownership.