Comment by jerf
That may be what is in the thesis, but in real Erlang, any process can list all processes on any node it can reach: https://www.erlang.org/doc/apps/erts/erlang.html#processes/0 (As the docs say, it lists "processes on the local node" but I'm fairly sure any process can RPC that to any connected node to get the local processes on that node) From there you've got a lot of introspection on the processes in question.
And beyond that, there is no sandboxing in Erlang that allows you to do anything like spawn a process that can't access the disk or network or anything like that. So in practice that doesn't even hardly buy you anything on a real system because if you were somehow running unauthenticated Erlang code you've already got access corresponding to the OS permissions of the running Erlang process. (Though for those not familiar with Erlang, "somehow running unauthenticated Erlang code" is very unlikely, to the point that it's not a realistic threat. I'm just speaking hypothetically here.)
The thesis may cover how such systems could be turned to a more secure context but it does not correspond to current Erlang.
There are many layers of capabilities. Unguessable process IDs would be necessary for network capabilities. A sandboxing environment would be necessary for system or process level capabilities. It's still worth having the network security even if process security isn't there. Very few language implementations can provide that level of security.