It's like that joke about "just one goat".
Failing to find anything that might suggest that rwall would do anything nasty beyond the bounds of the current domain (or at least up to the IMP), I tried it. I knew that rwall takes awhile to do its stuff, so I left it running and went back to my office. I assumed that anyone who got my message would let me know.. Boy, was I right about that! After the first few mail messages arrived from Purdue and Utexas, I begin to understand what was really going on and killed the rwall. I mean, how often do you expect to run something on your machine and have people from Wisconsin start getting the results of it on their screens?
It seems many of those risks have never really been solved - air traffic control failure being the exception.
"I have to wonder what other RPC services are open holes. We've managed to do some interesting, unauthorized, things with the YP service here at Berkeley, I wonder what the implications of this are."
Indeed these were famously abused in these early having days.
We had some people from a student organization which I will not name set up some servers with warez and other things in our network. This network was back then completely open to network and all students' machines had real, public, routable IP addresses and no firewall.
We had to tolerate the people even though the rules stated running intensive services was not allowed and I would normally had a script that would automatically ban a user for doing something like that.
I remember one day we (me and my roommate) decided to take a look at the server and we noticed it is some stock install of a Linux Mandrake which was known to be totally insecure. We decided to bet who is going to be faster to the server.
Half an hour later we were both telnetted to the server and chatting using wall, of all possibilities.
For those who don't remember, wall broadcasts messages to all terminals on the server.
Couple minutes later the owner of the server burst into our room scared that some hackers just invaded his precious student service.
You should see our faces.