[299] in linux-security and linux-alert archive
Re: YAWTCQ
daemon@ATHENA.MIT.EDU (Martin Schulze)
Wed Jul 26 14:05:13 1995
From: joey@finlandia.Infodrom.North.DE (Martin Schulze)
To: Thomas.Koenig@ciw.uni-karlsruhe.de (=?ISO-8859-1?Q?Thomas_K=F6nig?=)
Date: Fri, 21 Jul 1995 20:30:24 +0200 (MET DST)
Cc: linux-security@tarsier.cv.nrao.edu
In-Reply-To: <199507201605.SAA02467@mvmampc66.ciw.uni-karlsruhe.de> from "=?ISO-8859-1?Q?Thomas_K=F6nig?=" at Jul 20, 95 06:05:13 pm
Hi T-Rex!
}> Curiously, at jobs *are* owned by the user
}> (otherwise crond wouldn't know who to execute them as),
}
}This also serves as a sort of authenticication, on a system with
}restricted chown(), as Linux is, only the user can have created
}that file.
[ Speaking for at jobs, not for crontabs, just to avoid confusion ]
Yes, but wont't it be more secure to manage a database file containing
the user, group and file to execute? Then the script might be owned by
daemon.daemon or whatever, and you can't read it anymore.
And if I think about cheating a possibly existing quota, does there
exist a limitation in the length of at jobs? (haven't looked at the
source)
}The problems which occur when a program written with that assumption
}moves into a universe in which this doesn't hold are easy to imagine.
}
}> and it is possible to
}> edit them, and this does not pose any serious security
}> threat that I am aware of.
}
}This does not hold true for Linux.
}
}It is no longer possible to edit at jobs there in newer versions;
}as turned out recently, this was a very wise descision, because there
}did indeed lurk a potential fatal security hole there.
I do understand that. And it's also impossible to look at the script
after installing it. And that's - at least for me - bad, because every
once in a while I have to cancel such a job, but I don't know which
one. On the other hand it may also no good idea if they could be
readble after installing.
}Let's just hope that whoever implemented that particular system
}also made the scripts non - executable, in that case.
Uoh, mine are executable and they are owned by joey.users, but I can
neither read nor execute them. And they are NOT suid.
regards,
Joey
--
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