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Re: vulnerability in 8.6



Hello Salvatore,

I updated the Debian system and again exploit it successful.

$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo apt-get dist-upgrade

$ cat /etc/debian_version
8.6
$ uname -ar
Linux x 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u1 (2016-09-03) x86_64 GNU/Linux

Test:

$ ./dirtyc0w /etc/resolv.conf blabla (not root, normal user)
mmap 7faddc3f2000
madvise 0

procselfmem 600000000

$ cat /etc/resolv.conf
blabla8.8.8.8

Do I have to reinstall new Debian's?

~$ cat /etc/apt/sources.list

deb http://security.debian.org/ jessie/updates main contrib
deb-src http://security.debian.org/ jessie/updates main contrib

deb http://ftp.debian.org/debian/ jessie-updates main contrib
deb-src http://ftp.debian.org/debian/ jessie-updates main contrib

deb http://ftp.debian.org/debian/ jessie main contrib
deb-src http://ftp.debian.org/debian/ jessie main contrib

Regards,

~ Ozgur


2016-11-07 19:09 GMT+03:00 Salvatore Bonaccorso <carnil@debian.org>:
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



--
Ozgur

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