CS Qualifier OS Question on Shells

[Barry Margolin]

I think that the trojan horse issue is a red herring (to throw together
a few euphemisms).  If someone can replace someone else's shell on a
system where the shell is a user program, then he can just as easily get
the victim to execute a program which simulates the shell on a system
where the real shell is in the kernal; both of them require making the
victim execute a command.  If this is not the case, then the OS has
serious security problems.  Therefore, since the user-level shell
provides more flexibility to those who need it, it is the obvious
choice.
-- 
			Barry Margolin
			ARPA: barmar at MIT-Multics
			UUCP: ..!genrad!mit-eddie!barmar