Date: Wed, 11 Aug 2004 02:10:39 +0800 From: Xin LI <delphij@frontfree.net> To: Doug Barton <DougB@FreeBSD.org> Cc: "freebsd-security@FreeBSD.org" <freebsd-security@FreeBSD.org> Subject: Re: [PATCH] Tighten /etc/crontab permissions Message-ID: <20040810181039.GA3189@frontfree.net> In-Reply-To: <20040810095953.H1984@qbhto.arg> References: <20040810161305.GA161@frontfree.net> <20040810095953.H1984@qbhto.arg>
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--BOKacYhQ+x31HxR3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, Doug On Tue, Aug 10, 2004 at 10:02:09AM -0700, Doug Barton wrote: >=20 > On Wed, 11 Aug 2004, Xin LI wrote: >=20 > >Hi folks, > > > >While investigating OpenBSD's cron implementation, I found that they set > >the systemwide crontab (a.k.a. /etc/crontab) to be readable by the > >superuser only. The attached patch will bring this to FreeBSD by moving > >crontab out from BIN1 group and install it along with master.passwd. >=20 > Do you have a reason for wanting to do this other than, "OpenBSD does it= =20 > this way?" I personally see no problems, and some benefit for users=20 > being able to see the system crontab. If the superuser needs to run=20 > "secret" cron jobs, then there is root's crontab that can be used for=20 > this purpose. >=20 > Can you elaborate on your thinking? Well... This seems much more than "OpenBSD does it" to me :-) On a system that all users plays good, it does not matter if other users can see the crontab. However, if it gets compromised, chances that a badly configured system, say, with some permissions badly granted, would give the intruder a better chance to get more privilege if [s]he can read the crontab, and I think this is one of the reasons why the per-user cronta= bs are kept in /var/cron and without granting users to see each others'. I'm not sure if this is a sort of abusing systemwide crontabs, but the administrators at my company have used them to run some tasks periodly under other identities (to limit these tasks' privilege), and it provided a somewhat "centralized" management so they would prefer to use systemwide crontab rather than per-user ones. What do you think about the benefit for users being able to see the system crontab? I think knowing what would be executed under others' identity is (at least) not always a good thing, especially the users we generally don't fully trust... Cheers, --=20 Xin LI <delphij frontfree net> http://www.delphij.net/ See complete headers for GPG key and other information. --BOKacYhQ+x31HxR3 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (FreeBSD) iD8DBQFBGQ+fOfuToMruuMARAtmyAJ4r2KexkN1yT//vP6rt1gcS4Q87FwCeMcI5 SABDh7+mgJn1GjKTBWLpz1g= =FQRX -----END PGP SIGNATURE----- --BOKacYhQ+x31HxR3--
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