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Date:      Wed, 27 Mar 2002 09:00:06 -0500
From:      Bill Vermillion <bv@wjv.com>
To:        security@freebsd.org
Subject:   Question on su / possible hole
Message-ID:  <20020327140006.GA30556@wjv.com>

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I don't know if this is where I should ask, so apologies if it's
the wrong place.

There is a wheel group and only people who are in the wheel group
are to be able to su to the root account.

I like that approach because even if people has the root password
they can't su to root.

However I have found that if non-wheel-group user can su to a
user who has wheel privledges - the the non-wheel user can su to
root.

Since BSD doesn't use the EUID/EGID methods in SysV so you know
who the user is in reality, it would seem perhaps logical
to use the login id of the person to check wheel group privledges.

I have noted that this appears to me anyway, and may have missed
something else, that this is only way you can tell who the original
user is.

Because of this way to bypass not having a wheel group entry for a
user - this seems to me to be a potential security hole. IOW if
you have made sure those in wheel are authenticated so you know for
sure who they are you may assume that they are safe.  

I realize that it falls back to the user in the wheel group who has
had their password compromised.

It just strike me as odd with all the other safeguards in place
that this one can occur.

Does anyone know the reason behind this design, it it was done this
way purposely.  Am I being overly paranoid about this?

Thanks.

Bill

-- 
Bill Vermillion - bv @ wjv . com

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