Linux Kernel 2.6 Local Root Exploit

aquatix writes "This local root exploit (Debian, Ubuntu) seems to work everywhere I try it, as long as it's a Linux kernel version 2.6.17 to 2.6.24.1. If you don't trust your users (which you shouldn't), better compile a new kernel without vmsplice." Here is millw0rm's proof-of-concept code.

Comments

Re:Misleading

[shadow42]

I just successfully used this exploit on a Fedora 7 box running 2.6.22.4. A bit out of date, yes, but a great deal of "home users" who are running Fedora, Debian, Ubuntu (especially Ubuntu), etc., either don't know how to compile their own kernel, or don't care enough to try. Not everyone who uses Linux is going to bother compiling a custom kernel in order to fix a problem like this, especially if they don't have the skills of a sysadmin.

Re:For those that would rather write than read.

[McDutchie]

Nope, all you need is remote access to a local user account via ssh or something. Many users use weak passwords. Now you won't have to guess the root password.

Yes, I just verified the exploit on Linux 2.6.17.13 (Slackware 11.0) and Linux 2.6.21.5 (Slackware 12.0) and it works as advertised.

Funny comments :)

[K. S. Kyosuke]

There are some pretty funny comments in the source code, regrettably, most people won't understand them. Hell, as a Czech, I *am* probably supposed to understand them, if it were not for the obscure north-eastern dialect of Czech that all the rest of our country finds hilarious (and incomprehensible at the same time).

"Dovalim z knajpy a cumim ze Wojta zas nema co robit, kura." == something like "Just returned from the pub and saw that Wojta [a machine? Or a person? Unclear...] has nothing to do." [The last word might be a Czech expletive with a typo...?]
"Gizdi, tutaj mate cosyk na hrani, kym aj totok vykeca." == something like "Here's something for you to play with, boys, ..." [last for four words utterly incomprehensible :)]
"Stejnak je to stare jak cyp a aj jakesyk rozbite." == "Anyway, it's old as hell and somehow broken anyway"

The style (no way am I able to render *this* in English :)) makes me think that had drunk quite a bit before he wrote these gems. Pity that I don't have a good dictionary of spicy English. I'm just rolling on the floor and seriously laughing. :) Oh, and the exploit works, which is not that *funny*.

Re:Beauty of OSS

[Anonymous Coward]

The problem is now known so I'm sure a fix is already on the way. Holy shit, no kidding - the form of an exploit which fixes the bug live in the kernel mem.
nobody$ ./exploit
[..]
[+] mmap: 0xb7f29000 .. 0xb7f5b000
[+] root
root# ^D

nobody$ ./disable-vmsplice-if-exploitable
[..]
Exploit gone!
nobody$ ./exploit
[+] mmap: 0xb7f34000 .. 0xb7f66000
[-] vmsplice
nobody$ no root for me anymore!

By Morten Hustveit:
"a modification of the exploit that finds the address of sys_vmsplice in the
kernel (using /proc/kallsyms) and replaces the first byte with a RET instruction
(using mmap of /dev/kmem)" from
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=464953#14

This flaw is CVE-2008-0600

[iamamoose]

Upstream patch for the vulnerability tickled by that specific exploit is here
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=712a30e63c8066ed84385b12edbfb804f49cbc44

Red Hat tracking bug (Enterprise Linux 5 is affected, but 4,3, and 2.1 are not)
https://bugzilla.redhat.com/show_bug.cgi?id=432251

Fedora tracking bug
https://bugzilla.redhat.com/show_bug.cgi?id=432229

Ubuntu 7.10 generic kernel is affected.

[ikarous]

The poster who said that Ubuntu kernels are not affected was incorrect, at least partially. The exploit code works as advertised on my Ubuntu machines, both of which are running 7.10 with the latest generic kernel image.

This is incorrect

[bconway]

Vmsplice is part of the core kernel, it is not a configuration option. It is used all over the place.