Re: vulnerability in 8.6
Hi Salvatore, Ozgur,
You posted this url; https://www.debian.org/security/2016/dsa-3696
I've been looking in to this exploit, and did what Ozgur found on
Github, and I learned that my system is vulnerable. I had a difference,
which is that dirtyc0w, did overwrite the read-only 'foo' file, but it
hang, and it also did write up to the length of the original content of
that file. So my 'foo' was six bytes long and I attempted to overwrite
with a longer sequence, and it stopped. After seeing this had happened,
I started over with a new 'foo' file, and this time I attempted a
shorter byte sequence and it also hang. From what I've read, it doesn't
seem to hang.
I'm guessing that overwriting the sudoers file for example would make
the exploiter a rooted user on the exploited system..
But, I have looked for a update and I went to Debian package search and
searched for; 'kernel image 686
pae' [https://packages.debian.org/search?suite=stable§ion=all&arch=any&searchon=names&keywords=kernel+image+686+pae]
This gave one result, which is; 'kernel-image-3.16.0-4-686-pae-di' and
written with that, 'Linux kernel binary image for the Debian installer
3.16.36-1+deb8u1: i386'
And I read that I need a '+deb8u2' kernel?
Can someone explain to me what to do next? I have the assumption that a
'apt-get install "name-of-required-kerne-package"' would be sufficient?
If not, can someone point me in the right direction on what to do,
because the link Salvatore posted, it says on that page;
'For the stable distribution (jessie), these problems have been fixed in
version 3.16.36-1+deb8u2.
We recommend that you upgrade your linux packages.'
--
Richard Waterbeek <richardwbb@versatel.nl>
Salvatore Bonaccorso schreef op ma 07-11-2016 om 17:09 [+0100]:
> Hi,
>
> On Mon, Nov 07, 2016 at 06:54:55PM +0300, Ozgur wrote:
> > Hi all,
> >
> > I have been reading security articles and I seen a test with Debian Linux
> > vulnerability of kernel. I tested and given a successful exploit.
> >
> > List a vuln:
> >
> > https://github.com/dirtycow/dirtycow.github.io/wiki/PoCs
> >
> > My testing:
> >
> > dirtycow.c (status: success)
> > cowroot.c (status: success)
> >
> > For example, I have installed Debian and kernel version are as follow:
> >
> > Linux 3.16.0-4-amd64 (Debian 8.6)
> >
> > I created a "zoo" file with root privileges and locked a file:
> >
> > # echo I'm a root > foo
> > # chmod 0404 foo
> > # ls -la foo
> > -r-----r-- 1 root root 11 Nov 7 10:13 foo
> >
> > then I'm return my user (not root) and I downloaded the exploit script and
> > run it:
> >
> > $ gcc -pthread dirtyc0w.c -o dirtyc0w
> > $ ./dirtyc0w foo blabla
> > $ cat foo
> > blabla
> >
> > what is the suggestion on this exploit?
>
> Have you installed the Kernel update as per the security advisory
> DSA-3696-1? Which kernel image do you have installed, which kernel is
> running?
>
> [0] https://www.debian.org/security/2016/dsa-3696
>
> Regards,
> Salvatore
>
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