Re: how an hacker can bypass a chrooted environement ?

[Marco Ivaldi <raptor () 0xdeadbeef info>]

On Sun, 14 May 2006, Norbert Francois wrote:

> Thank you very much for your replies.
>
> But there's smth I still don't understand. Few months ago I tried to 
> install a jail chroot with "jail" 
> (http://www.jmcresearch.com/projects/jail/howto.html). In the chrooted 
> environement I didn't copy programs like "chroot" (itself), "mknod" or 
> "mount" known to be dangerous... So the only way to bypass this chroot 
> is to manually upload these tools ? If it is the case, the attacker has 
> to inject a code opening a socket on the victim's computer, isn't it ?

Obviously, the mentioned chroot(2), mknod(2) and mount(2) aren't programs, 
but actual syscalls:

$ man 2 chroot
$ man 2 mknod
$ man 2 mount

Unless there are some mechanisms to enforce syscall execution limitation 
(like systrace or similar) in place, you are able to execute any syscall 
inside a chroot jail -- provided you have the required privileges, of 
course.

Take also a look at the differences between regular chroot and FreeBSD's 
jail, it might be of some interest to you:

http://en.wikipedia.org/wiki/Chroot_jail
http://en.wikipedia.org/wiki/FreeBSD_Jail

Hope this helps to clarify things a bit;)

Cheers,

--
Marco Ivaldi
Antifork Research, Inc.   http://0xdeadbeef.info/
3B05 C9C5 A2DE C3D7 4233  0394 EF85 2008 DBFD B707


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