Re: AppArmor FAQ

From: david
Date: Sat Jun 09 2007 - 20:08:17 EST

On Sun, 10 Jun 2007, Pavel Machek wrote:

I'm not sure if AppArmor can be made good security for the general case,
but it is a model that works in the limited http environment
(eg .htaccess) and is something people can play with and hack on and may
be possible to configure to be very secure.

Perhaps -- until your httpd is compromised via a buffer overflow or
simply misbehaves due to a software or configuration flaw, then the
assumptions being made about its use of pathnames and their security
properties are out the window.

How is it that you think a buffer overflow in httpd could allow an
attacker to break out of an AppArmor profile? This is exactly what
AppArmor was designed to do, and without specifics, this is just

No, it is not, I already broke AppArmor once, and it took me less then
one hour.

Give me machine with root shell, and make app armor permit everything
but reading /etc/secret.file. AppArmor is not designed for this, but
if you want to claim your solution works, this looks like a nice test.

Actually, give password to everyone, and see who breaks it first.

you admit that AA isn't designed for this and then you set this as the
test, doesn't that seem unreasonable to you?

httpd's run at root priviledge, AFAICT, and Crispin just accused
someone of spreading fud. Exploited httpd is root shell.

only poorly designed webservers run as root. in general they have not been running as root for many years.

however, if you are willing to take a limited shell (root or any other user) that's a different story, what would you want the shell to have permission to do? would read files in directory A and write files in directory B be good enough? or would you want it to be able to execute specific commands?

note that at the moment I am not comitting anyone to provide a box for such a challange, but I'm interested in what you would consider a suitable test.

David Lang
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