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From: charles@hpcvcd.UUCP
Newsgroups: comp.sources.d
Subject: Re: Another kind of su program (source)
Message-ID: <4310001@hpcvcd.HP>
Date: Sun, 8-Feb-87 21:20:20 EST
Article-I.D.: hpcvcd.4310001
Posted: Sun Feb  8 21:20:20 1987
Date-Received: Wed, 11-Feb-87 07:15:51 EST
References: <608@vu-vlsi.UUCP>
Organization: Hewlett-Packard Co., Corvallis, Oregon
Lines: 58

>> Both of these programs (performing password-free su) seem dangerous
>> to me- if one of the authorized users were to accidently leave themself
>> logged on, anyone could come along and su from their terminal.
>
>Short reply:
>Yes a password-free su (PWFSU) is dangerous.
>So is typing the root password all the time.
>I feel that the security trade-off is a wash,
>and PWFSUs win because they are more convenient.

At this site we have a program called su2 which requires the user to
type his OWN password.  He never knows the root password, but can
still get access to that power occasionally.  Naturally, su2 only
allows authorized users to become superuser.  Some advantages to this
are that the real superuser can change the root password as often as
he likes.  He can remove users from the su2 list without asking their
permission and without changing the root password.  He also does not
need to know their passwords.

----------------------------------------------
I did not write su2.  Sorry, I can not post it.
----------------------------------------------

>Long reply:
>This weakness occurs on all normal UN*X systems anyway.
>Anyone can come along and install a trojan horse 'su',
>in the authorized user's bin, which steals the root password.

Wrong.  I am not even a superuser and I don't allow anything that
weak on my path.  All common commands are in protected directorys,
and are early in my PATH.  I have two unprotected directorys on my
PATH, and they are at the end of it.  One of them is ".", and I am
sometimes tempted to remove it altogether.  I know many people put
"." first on their PATH.  This is like hanging a "Kick Me" sign on
your back.  I am tempted to put a program called "ls" in one of my
directorys.  The program would do nothing but make it look like it
had caused them damage.

>There are lots of other ways to exploit a logged-in terminal.
>There is always "find / -exec rm -f {} ';'", just to be malicious.

"rm -rf /" is shorter.

>> it makes the knowledge of an authorized sus/slide users password
>> equivalent to knowing the root password.

Alas, this is a problem.

>Or just do what we do -- threaten our users with bodily harm
>if they exploit security weaknesses.  Works great.
>	Tom ("just kidding") Truscott
>----------

I know of someone unknowingly running the equivalent of
"rm -rf /users/*".

	Charles Brown
	hplabs!hp-pcd!charles