Date: Sat, 9 Mar 2002 15:34:42 -0500 From: Garance A Drosihn <drosih@rpi.edu> To: arch@FreeBSD.ORG Subject: Re: Fix for login.c, added questions Message-ID: <p05101531b8b01b012e1c@[128.113.24.47]> In-Reply-To: <p05101530b8b014ffc5c7@[128.113.24.47]>
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At 2:57 PM -0500 3/9/02,
Garance A Drosihn wrote to freebsd-audit:
>In my testing, the simple fix is:
>
>Index: login.c
Reading thru login.c, it seems to me that we should probably
consider some other changes too. One thing I noticed, for
instance, is that login.c tries to setup a 300-second timeout,
but apparently that timeout is masked off somewhere inside the
auth_pam() processing. So, if a person types in a login name,
a wrong password, types in the same login name and then just
sits in the next password prompt, the session (apparently)
never times out. Or at least it doesn't seem to have timed
out for me in the more than 20 minutes I've left it sitting
there on a console login.
One thing the code tries to do is avoid a syslog message
for the case of:
login myid
wrong password
login myid
correct password
My claim is that this goal complicates the code enough that it
also opens up some subtle opportunities for nefarious souls
to be guessing passwords without syslog messages occurring.
For one, it means you have to delay writing the syslog message
at least until you read in the new userid, which is under the
control of the very user who (perhaps) is trying to do something
nasty.
Do people think we could drop the nice idea of avoiding the
syslog message in the above situation, and just always write
out the syslog message right when we know the password is
wrong? That will increase the number of syslog messages,
which might alarm some users, but I think it's safer. Perhaps
we could avoid that alarm by also writing out a syslog message
if the session gives the correct password for a userid after
having given a failed password.
--
Garance Alistair Drosehn = gad@eclipse.acs.rpi.edu
Senior Systems Programmer or gad@freebsd.org
Rensselaer Polytechnic Institute or drosih@rpi.edu
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