Penetration Testing mailing list archives
Re: how an hacker can bypass a chrooted environement ?
From: Marco Ivaldi <raptor () 0xdeadbeef info>
Date: Tue, 16 May 2006 17:36:17 +0200 (CEST)
Hey pen-test, On Fri, 12 May 2006, Rob wrote:
from man 2 chroot(): -- Note that this call does not change the current working directory, so that '.' can be outside the tree rooted at '/'. In particular, the super-user can escape from a 'chroot jail' by doing 'mkdir foo; chroot foo; cd ..'. -- Also, mknod() some device files like /dev/kmem or /dev/hda1, then use root priviledges to muck with kernel, or raw write data to disk.
Beside the already described techniques, here follows a quick summary of some other rather old tricks to break out of the chroot jail: 1) Load a kernel module;) Capability needed: CAP_SYS_MODULE. 2) Speaking about the already mentioned mknod() technique (capability needed: CAP_MKNOD), you could also use it to abuse ttys and virtual file systems through the mount() syscall (capability needed: CAP_SYS_ADMIN): procfs, devfs, devpts. 3) Inject code through ptrace() into a process outside the chroot jail, provided you meet the required conditions to do so. This could work for instance when the uid nobody is shared between several processes (semi-common misconfiguration). Depending on the situation, this could also be accomplished even with uid != 0. For further details, see also: http://www.phrack.org/phrack/59/p59-0x0c.txt 4) Other uid != 0 tricks: (UNIX) sockets, shared memory segments and other IPCs, exploiting local kernel vulnerabilities;), some other application specific points. 5) Abuse sysctl() to set the modprobe binary path? Direct access to I/O ports? Sniff network traffic? Impersonate a local administration service (sshd)? Change netfilter rules? And so on... (you need different capabilities for those). I'm sure i left some possibilities out (use your fantasy), but i guess this pretty much shows how you shouldn't blindly rely only on chroot to secure your servers. YMMV. Cheers, -- Marco Ivaldi Antifork Research, Inc. http://0xdeadbeef.info/ 3B05 C9C5 A2DE C3D7 4233 0394 EF85 2008 DBFD B707 ------------------------------------------------------------------------------ This List Sponsored by: Cenzic Concerned about Web Application Security? Why not go with the #1 solution - Cenzic, the only one to win the Analyst's Choice Award from eWeek. As attacks through web applications continue to rise, you need to proactively protect your applications from hackers. Cenzic has the most comprehensive solutions to meet your application security penetration testing and vulnerability management needs. You have an option to go with a managed service (Cenzic ClickToSecure) or an enterprise software (Cenzic Hailstorm). Download FREE whitepaper on how a managed service can help you: http://www.cenzic.com/news_events/wpappsec.php And, now for a limited time we can do a FREE audit for you to confirm your results from other product. Contact us at request () cenzic com for details. ------------------------------------------------------------------------------
Current thread:
- how an hacker can bypass a chrooted environement ? Norbert François (May 12)
- Re: how an hacker can bypass a chrooted environement ? alan (May 12)
- Re: how an hacker can bypass a chrooted environement ? Justin Ferguson (May 12)
- Re: how an hacker can bypass a chrooted environement ? Peter Kosinar (May 12)
- Re: how an hacker can bypass a chrooted environement ? Rob (May 12)
- Re: how an hacker can bypass a chrooted environement ? Tonnerre Lombard (May 12)
- Re: how an hacker can bypass a chrooted environement ? Norbert François (May 14)
- <Possible follow-ups>
- Re: how an hacker can bypass a chrooted environement ? Marco Ivaldi (May 16)
- RE: how an hacker can bypass a chrooted environement ? David M. Zendzian (May 17)
- Re: how an hacker can bypass a chrooted environement ? Chris Byrd (May 18)
- Re: how an hacker can bypass a chrooted environement ? Marco Ivaldi (May 17)
- Re: RE: how an hacker can bypass a chrooted environement ? john . fellers (May 18)
- Re: how an hacker can bypass a chrooted environement ? alan (May 12)