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Re: [Apparmor-dev] Re: Re: [SC-L] Re: [Owasp-dotnet] RE: 4 Questions:Latest IE vulnerability, Firefox vs IE security, User vs Admin risk profile, and browsers coded in 100% Managed Verifiable code
From: "Ed Reed (Aesec)" <Ed.Reed () aesec com>
Date: Fri, 07 Apr 2006 15:03:03 -0400

Indeed, one compelling use of AppArmor is to create root-subset profiles for hard links to /bin/bash so as to effectively partition administrative privs.

Even root users, when executing within a confined profile, are constrained - that's the mandatory access control aspect of AppArmor.

You can literally give someone a profiled shell with root privs and let them try to do something the profile doesn't allow. If you don't give them "ls", they'll be unable to list their current directory, anywhere, as long as they're confined.

You can use this to create profiles for backup operators, help desk technicians, Human Resources user creation tasks, or my favorite -

Oracle Database Administrators - who have root privs to do stuff they need to do to their Oracle files and directories, and even processes - but who cannot bounce the machine or reformat disks or do other stuff they have no need to do.

It's one approach to an RBAC-sort of control.

Ed

Matt Lidestri wrote:
Hello,
I have used AppArmor a bit, and must say that I like it a lot. I have used it on a few servers, and in some security competitions. As a HIPS, it is easy to use and fairly effective (from what I have seen). I just saw your question and it sparked my curiousity. From some quick googling, I presume that cap_setuid allows a process or call to be passed as another user (we'll say root for now). I wondered if root was exempt from the AppArmor rules (although I doubted it), so I configured my VMed webserver to access a denied config file for mod_security, and then started apache as root. It failed with an error from AppArmor claiming that access was denied to the configuration file. I restored the permissions in AppArmor and received a different error, apparently the Apache developers were smart enough to disallow apache to be run as root. Nonetheless, AppArmor would not even let it get this far, so even root privileges cannot override AppArmor profiles. Regards,
Matt

On 4/6/06, *Brian Eaton* <eaton.lists () gmail com <mailto:eaton.lists () gmail com>> wrote:

    On 4/5/06, Crispin Cowan <crispin () novell com
    <mailto:crispin () novell com>> wrote:
    > Pascal Meunier wrote:
    > >  but as you posted an example profile with "capability
    setuid", I must
    > > admit I am curious as to why an email client needs that.
    > Well now that is a very good question, but it has nothing to do
    with
    > AppArmor. The AppArmor learning mode just records the actions
    that the
    > application performs. With or without AppArmor, the Thunderbird mail
    > client is using cap_setuid. AppArmor gives you the opportunity
    to *deny*
    > that capability, so you can try blocking it and find out. But for
    > documentation on why Thunderbird needs it, you would have to look at
    > mozilla.org <http://mozilla.org> not the AppArmor pages.

    Does cap_setuid give a program enough authority to break out of the
    AppArmor profile?

    Regards,
    Brian

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Matt Lidestri
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