Date: Fri, 18 Dec 1998 09:29:59 -0500 From: Graeme Tait <graeme@echidna.com> To: "Bond, Jeffery" <Jeff.Bond@nectech.co.uk> Cc: "'FreeBSD questions'" <questions@FreeBSD.ORG>, "'cjc@cc942873-a.ewndsr1.nj.home.com'" <cjc@cc942873-a.ewndsr1.nj.home.com> Subject: Re: Basic Security Question Message-ID: <367A66E7.13DE@echidna.com> References: <084DD226F592D211988800A024AC583B02B783@exchange.nectech.co.uk>
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Bond, Jeffery wrote:
>
> >Mark Ovens wrote,
> >
> >> and on all the Sparcs running SunOS4.1.3_U1 here are:
> >>
> >> gppsun4:/{8}% ls -ldug etc
> >> drwxrwsrwx 10 bin staff 2048 Dec 17 09:30 etc
> >>
> >> which is even less secure as it's writable by all!
> >
> >I may be dense. Is that some kind of joke or something? As dense as I
> >am, I know for sure that even I could take any account on a system
> >with permissions like that and have control of root in this many
> >keystrokes:
> >
> >% cd /etc
> >% echo "root::0:0:Evil Root:/:/bin/csh" > passwd.new
> >% mv passwd passwd.old
> >% mv passwd.new passwd
> >% su
> >#
>
> Just because the directory is writable, this doesnt mean the existing files
> in it are too. You won't be able to do 'mv passwd passwd.old'.
As I understand it, file delete and creation are controlled by the
permissions of the *containing* directory, not the file permissions. It's
obvious enough it has to be that way for creation, as there is no file to
have permissions, and logically, what you can (not) create, you should be
(not) able to delete. If a file lacks write permission for the relevant
user/group/other category, you will get a warning on deletion, but it can be
overidden if the appropriate directory permission is write.
The mv command is possible as stated above.
But the hack given didn't work for me - is that because you need to fiddle
master.passwd?
--
Graeme Tait - Echidna
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