Hi, thanks for your response
Yes, I'm on Debian and it appears to allow invalid
groups. My problem is that noone else (with the
exception of the hosting company - I'm not sure about
them) has root access to the server, and I hadn't done
anything to make the group UID's change. I don't SSH
in often, only to check logs, settings, or install
something.
The reason I noticed it was that my FTP client was
giving me errors about not being able to list the
directory - which I had never seen before even though
I regularly upload and delete files via FTP with the
exact same client on the exact same computer.
So, all told, I wouldn't mind if I had done it
accidentally, I just don't see how I could have -
especially since if it was recursive it would have
changed all the files in the directory to the same
group, and they had a couple different non-existent
groups.
--- "Nicholson, Dale" <DNicholson@APACMail.com> wrote:
On some *nix flavors chown allows you to change the
group to whatever you
enter even when the group does not really exist. I
don't know if you are on
one of those, but you can check by trying to chown
the files to some other
group and see.
chown larry:madeupgroup foot.php
If this returns "chown: unknown group id
madeupgroup" then you might want to
get more concerned. If it allows you to change to a
made up group name it
means this might have been done on accident.
In any case you can at least change the group back
to the correct one.
I have not heard of an exploit that does this but
that does not mean it
doesn't exist.
Dale
-----Original Message-----
From: sf_submit@yahoo.com
[mailto:sf_submit@yahoo.com]
Sent: Thursday, September 22, 2005 8:21 PM
To: security-basics@securityfocus.com
Subject: Group permissions changed
Fairly recently I noticed my ftp client wouldn't
list files in certain
directories on my server anymore - so I ssh'd in
(it's dedicated), and did a
ls -aFl on the files, hoping to see what the problem
was - here are a few of
the results:
-rw-r--r-- 1 larry 503 371 2005-02-25 08:36
head.php
-rw-r--r-- 1 larry 48 873 2005-09-09 03:23
foot.php
I never set the group ids to 503 or 48, so I checked
just to make sure - and
no groups with those ids even exist. Is there an
exploit/tool that causes
this, and should I be worried?
I checked the processes running, and everything
seems to be OK - same with
any processes connecting to the internet.
I'd appreciate any comments
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