What is CVE-2016-0728 bug?
As per the original research post:
CVE-2016-0728 is caused by a reference leak in the keyrings facility. Before we dive into the details, let’s cover some background required to understand the bug. It can successfully escalates privileges from a local user to root.
A list of affected Linux distros
Is my Linux distro version affected by CVE-2016-0728? The “Possible use-after-free vulnerability in keyring facility, CVE-2016-0728” are as follows:
- Red Hat Enterprise Linux 7
- CentOS Linux 7
- Scientific Linux 7
- Debian Linux stable 8.x (jessie)
- Debian Linux testing 9.x (stretch)
- SUSE Linux Enterprise Desktop 12
- SUSE Linux Enterprise Desktop 12 SP1
- SUSE Linux Enterprise Server 12
- SUSE Linux Enterprise Server 12 SP1
- SUSE Linux Enterprise Workstation Extension 12
- SUSE Linux Enterprise Workstation Extension 12 SP1
- Ubuntu Linux 14.04 LTS (Trusty Tahr)
- Ubuntu Linux 15.04 (Vivid Vervet)
- Ubuntu Linux 15.10 (Wily Werewolf)
- Opensuse Linux LEAP 42.x and version 13.x
- Oracle Linux 7
How do I fix CVE-2016-0728 on Linux?
Type the commands as per your Linux distro. You need to reboot the box. Before you apply patch, note down your current kernel version:
$ uname -a
$ uname -mrs
Sample outputs:
Linux 3.13.0-74-generic x86_64
Debian or Ubuntu Linux
$ sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade
Sample outputs:
Reading package lists... Done Building dependency tree Reading state information... Done Calculating upgrade... Done The following packages were automatically installed and are no longer required: git-man liberror-perl Use 'apt-get autoremove' to remove them. The following NEW packages will be installed: linux-headers-3.13.0-76 linux-headers-3.13.0-76-generic linux-image-3.13.0-76-generic linux-image-extra-3.13.0-76-generic The following packages will be upgraded: linux-generic linux-headers-generic linux-image-generic 3 upgraded, 4 newly installed, 0 to remove and 0 not upgraded. Need to get 61.6 MB of archives. After this operation, 271 MB of additional disk space will be used. Do you want to continue? [Y/n] y Get:1 http://security.ubuntu.com/ubuntu/ trusty-security/main linux-image-3.13.0-76-generic amd64 3.13.0-76.120 [15.2 MB] Get:2 http://security.ubuntu.com/ubuntu/ trusty-security/main linux-image-extra-3.13.0-76-generic amd64 3.13.0-76.120 [36.8 MB] Get:3 http://security.ubuntu.com/ubuntu/ trusty-security/main linux-generic amd64 3.13.0.76.82 [1,780 B] .... ... ..... Setting up linux-image-extra-3.13.0-76-generic (3.13.0-76.120) ... run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 3.13.0-76-generic /boot/vmlinuz-3.13.0-76-generic run-parts: executing /etc/kernel/postinst.d/dkms 3.13.0-76-generic /boot/vmlinuz-3.13.0-76-generic run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.13.0-76-generic /boot/vmlinuz-3.13.0-76-generic update-initramfs: Generating /boot/initrd.img-3.13.0-76-generic run-parts: executing /etc/kernel/postinst.d/zz-update-grub 3.13.0-76-generic /boot/vmlinuz-3.13.0-76-generic Generating grub configuration file ... Found linux image: /boot/vmlinuz-3.13.0-76-generic Found initrd image: /boot/initrd.img-3.13.0-76-generic Found linux image: /boot/vmlinuz-3.13.0-74-generic Found initrd image: /boot/initrd.img-3.13.0-74-generic No volume groups found done Setting up linux-image-generic (3.13.0.76.82) ... Setting up linux-headers-3.13.0-76 (3.13.0-76.120) ... Setting up linux-headers-3.13.0-76-generic (3.13.0-76.120) ... Examining /etc/kernel/header_postinst.d. run-parts: executing /etc/kernel/header_postinst.d/dkms 3.13.0-76-generic /boot/vmlinuz-3.13.0-76-generic Setting up linux-headers-generic (3.13.0.76.82) ... Setting up linux-generic (3.13.0.76.82) ...
Reboot the server:
$ sudo reboot
RHEL / CentOS Linux
$ sudo yum update
$ sudo reboot
Sample outputs:
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
* base: centos.excellmedia.net
* epel: mirrors.hustunique.com
* extras: centos.excellmedia.net
* updates: centos.excellmedia.net
Resolving Dependencies
--> Running transaction check
---> Package kernel.x86_64 0:3.10.0-327.4.5.el7 will be installed
---> Package kernel-devel.x86_64 0:3.10.0-327.4.5.el7 will be installed
---> Package kernel-headers.x86_64 0:3.10.0-327.4.4.el7 will be updated
---> Package kernel-headers.x86_64 0:3.10.0-327.4.5.el7 will be an update
---> Package kernel-tools.x86_64 0:3.10.0-327.4.4.el7 will be updated
---> Package kernel-tools.x86_64 0:3.10.0-327.4.5.el7 will be an update
---> Package kernel-tools-libs.x86_64 0:3.10.0-327.4.4.el7 will be updated
---> Package kernel-tools-libs.x86_64 0:3.10.0-327.4.5.el7 will be an update
---> Package ntp.x86_64 0:4.2.6p5-22.el7.centos will be updated
---> Package ntp.x86_64 0:4.2.6p5-22.el7.centos.1 will be an update
---> Package ntpdate.x86_64 0:4.2.6p5-22.el7.centos will be updated
---> Package ntpdate.x86_64 0:4.2.6p5-22.el7.centos.1 will be an update
---> Package python-perf.x86_64 0:3.10.0-327.4.4.el7 will be updated
---> Package python-perf.x86_64 0:3.10.0-327.4.5.el7 will be an update
--> Finished Dependency Resolution
--> Running transaction check
---> Package kernel.x86_64 0:3.10.0-229.11.1.el7 will be erased
---> Package kernel-devel.x86_64 0:3.10.0-229.11.1.el7 will be erased
--> Finished Dependency Resolution
Dependencies Resolved
======================================================================
Package Arch Version Repository
Size
======================================================================
Installing:
kernel x86_64 3.10.0-327.4.5.el7 updates 33 M
kernel-devel x86_64 3.10.0-327.4.5.el7 updates 11 M
Updating:
kernel-headers x86_64 3.10.0-327.4.5.el7 updates 3.2 M
kernel-tools x86_64 3.10.0-327.4.5.el7 updates 2.4 M
kernel-tools-libs x86_64 3.10.0-327.4.5.el7 updates 2.3 M
ntp x86_64 4.2.6p5-22.el7.centos.1 updates 543 k
ntpdate x86_64 4.2.6p5-22.el7.centos.1 updates 84 k
python-perf x86_64 3.10.0-327.4.5.el7 updates 2.4 M
Removing:
kernel x86_64 3.10.0-229.11.1.el7 @updates 131 M
kernel-devel x86_64 3.10.0-229.11.1.el7 @updates 32 M
Transaction Summary
======================================================================
Install 2 Packages
Upgrade 6 Packages
Remove 2 Packages
Total download size: 55 M
Is this ok [y/d/N]: y
Downloading packages:
Delta RPMs reduced 11 M of updates to 4.6 M (57% saved)
(1/8): kernel-headers-3.10.0-327.4.5.el7.x86_64. | 3.2 MB 00:17
(2/8): ntp-4.2.6p5-22.el7.centos.1.x86_64.rpm | 543 kB 00:03
(3/8): ntpdate-4.2.6p5-22.el7.centos.1.x86_64.rp | 84 kB 00:00
...
...
....
Installed:
kernel.x86_64 0:3.10.0-327.4.5.el7
kernel-devel.x86_64 0:3.10.0-327.4.5.el7
Updated:
kernel-headers.x86_64 0:3.10.0-327.4.5.el7
kernel-tools.x86_64 0:3.10.0-327.4.5.el7
kernel-tools-libs.x86_64 0:3.10.0-327.4.5.el7
ntp.x86_64 0:4.2.6p5-22.el7.centos.1
ntpdate.x86_64 0:4.2.6p5-22.el7.centos.1
python-perf.x86_64 0:3.10.0-327.4.5.el7
Complete!Suse Enterprise Linux or Opensuse Linux
To apply all needed patches to the system type:
# zypper patch
# reboot
Or version specific info:
SUSE Linux Enterprise Workstation Extension 12-SP1
# zypper in -t patch SUSE-SLE-WE-12-SP1-2016-124=1
USE Linux Enterprise Software Development Kit 12-SP1
# zypper in -t patch SUSE-SLE-SDK-12-SP1-2016-124=1
SUSE Linux Enterprise Server 12-SP1
# zypper in -t patch SUSE-SLE-SERVER-12-SP1-2016-124=1
SUSE Linux Enterprise Module for Public Cloud 12
# zypper in -t patch SUSE-SLE-Module-Public-Cloud-12-2016-124=1
SUSE Linux Enterprise Live Patching 12
# zypper in -t patch SUSE-SLE-Live-Patching-12-2016-124=1
SUSE Linux Enterprise Desktop 12-SP1
# zypper in -t patch SUSE-SLE-DESKTOP-12-SP1-2016-124=1
To bring your system up-to-date, run
# zypper patch && reboot
Verification
You need to make sure your version number changed:
$ uname -a
$ uname -r
$ uname -mrs
The version of the kernel a system is running can be confirmed with the uname command. A list of bug fixed kernel version is as follows:
- Ubuntu Linux 14.04 LTS : 3.13.0-76 (package version 3.13.0-76.120)
- Debian Linux 8.x : 3.16.0-4 (package version 3.16.7-ckt20-1+deb8u3)
- SUSE Linux Enterprise Server 12 SP1 : 3.12.51-60.25.1
- RHEL 7 : 3.10.0-327.4.5.el7.x86_64
- CentOS 7 : Same as RHEL 7.
Trying out exploit code
You can try proof-of-concept code to find out if your kernel is secure or not. Use the wget command to grab the sample code:
$ wget https://gist.githubusercontent.com/PerceptionPointTeam/18b1e86d1c0f8531ff8f/raw/5a90e6f98de85f35708087620de73bed3bf16880/cve_2016_0728.c
Compile it as follows (make sure you install the gcc compiler and keyutils developers libraries):
$ gcc cve_2016_0728.c -o cve_2016_0728 -lkeyutils -Wall
Run it as follows:
$ ./cve_2016_0728 PP_KEY
The full exploit which runs on kernel, takes about 30 minutes to run on Intel Core i7-5500 CPU:
Fig.01: CVE-2016-0728 point of concept exploit code
CentOS 7.2: Exploit code failed.
References
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| Category | List of Unix and Linux commands |
|---|---|
| File Management | cat |
| Firewall | Alpine Awall • CentOS 8 • OpenSUSE • RHEL 8 • Ubuntu 16.04 • Ubuntu 18.04 • Ubuntu 20.04 |
| Network Utilities | dig • host • ip • nmap |
| OpenVPN | CentOS 7 • CentOS 8 • Debian 10 • Debian 8/9 • Ubuntu 18.04 • Ubuntu 20.04 |
| Package Manager | apk • apt |
| Processes Management | bg • chroot • cron • disown • fg • jobs • killall • kill • pidof • pstree • pwdx • time |
| Searching | grep • whereis • which |
| User Information | groups • id • lastcomm • last • lid/libuser-lid • logname • members • users • whoami • who • w |
| WireGuard VPN | Alpine • CentOS 8 • Debian 10 • Firewall • Ubuntu 20.04 |
Oh! Please update the code for Debian and Ubuntu . Provide only :-
sudo apt-get update
Don’t let user’s jump into upgrade if they are not willing too.
Thanks for the heads up. I’ve updated the page.
sysctl -w kernel/kptr_restrict=1 should do the job too.
Heya,
Which is the patched kernel version for CentOS7?
Maybe nice to include that in the post.
What? Can’t read?
RHEL / CentOS Linux
The package will be released soon on both CentOS and RHEL 7
So it’s been there since 2012. It means most of the linux system exposed on the public has a high probability of being a bot.
Not likely. The vulnerability was discovered by Perception Point, and did not just appear live already in use. Today’s announcement almost certainly follows on the heels of a disclosure process that started 2 weeks ago. Critical vendors and operators have probably been patched for a while now.
local exploit, so if you have a “linux system exposed on the public” does not necessarily mean a high probability..
The attacker would need a local account first, so hopefully you’ve kept up on your other safe computing practices (security updates applied in reasonable time, firewalls/acls, etc)
CentOS 6 is also affected if you’re using Xen4CentOS.
should’t it be
sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade
(3 x sudo ?)
Yes. Sorry about that.
Oracle Enterprise Linux 6 with UEK Kernel (3.8) should also be included in the list.
Debian’s “dist-upgrade” command miss “sudo” that actually updating kernel
Change
sudo apt-get update && sudo apt-get upgrade && apt-get dist-upgradeto
sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgradeThanks for the heads up!
I have a couple of comments/questions;
Question 1: As BradErz asked, what kernel version are we looking for that has been patched?
Question 2: If this vulnerability has been around for 3 years, why is CentOS 7 affected while CentOS 6 is not? Just curious.
This bug affects kernel version 3.8 and above. CentOS 7/RHEL 7 comes with version 3.10. CentOS 6 or older has 2.6.xx series kernel. So they are not affected.
The Ubuntu system I built had the kernel version 3.16.0-40, and it was updated to 3.19.
So was 3.16-040 actually vulnerable in the first place?
The document says to update it to 3.13.0-76, so anything above that specific version should be good, right?
Is there something we can run to verify if the vulnerability is still there?
The faq has been updated to include the PoC.
That’s awesome! Thank you Gite <3
Just a small typo..
it should be: .”/cve_2016_0728″ (instead of “./cve_2016_072”
Opps. I fixed it. I appreciate your feedback and time.
Hi.in RHEL / CentOS Linux section you said that :”The package will be released soon on both CentOS and RHEL 7″
this means we cant patch this bug with sudo yum update and sudo reboot commands?
Patch is already released. That was on 19th/Jan/2016. I will update the page soon.
I can’t find any information about the update.
According to Redhat the last kernel update was on 5th.
kernel-3.10.0-327.4.4.el7.x86_64.rpm
RHN and CentOS mailing list
3.10.0-327.4.4.el7.x86_64 was released on 19th/Jan/2016. You need this version. I tested sample C and it didn’t worked. So the version I posted is 100% safe.
that is strange:
Here is the official update from 25.01.16
https://rhn.redhat.com/errata/RHSA-2016-0064.html
You are right. It is fixed in 3.10.0-327.4.5.el7.x86_64. I just verified it:
rpm -q --changelog kernel | grep -i cve-2016 - [security] keys: Fix keyring ref leak in join_session_keyring() (David Howells) [1298931 1298036] {CVE-2016-0728}The page has been updated. Thanks!
and what about voyage linux?? has it vulnerability?? I’m using voyage 0.10.0 with 3.16.7- ckt9-voyage
I presume that mint 17.3 cinnamon is included here?
You miss-spelt uname in verification section: `umame`
I suppose this vulnerability is for the servers or machines which have compiler access to unprivileged users enabled ?