To find out if your server is affected, check your kernel version.
- uname -rv
You’ll see output like this:
4.4.0-42-generic #62-Ubuntu SMP Fri Oct 7 23:11:45 UTC 2016
If your version is earlier than the following, you are affected:
- 4.8.0-26.28 for Ubuntu 16.10
- 4.4.0-45.66 for Ubuntu 16.04 LTS
- 3.13.0-100.147 for Ubuntu 14.04 LTS
- 3.2.0-113.155 for Ubuntu 12.04 LTS
- 3.16.36-1+deb8u2 for Debian 8
- 3.2.82-1 for Debian 7
- 4.7.8-1 for Debian unstable
Some versions of CentOS can use this script provided by RedHat for RHEL to test your server’s vulnerability. To try it, first download the script.
- wget https://access.redhat.com/sites/default/files/rh-cve-2016-5195_1.sh
Then run it with
- bash rh-cve-2016-5195_1.sh
If you’re vulnerable, you’ll see output like this:
Your kernel is 3.10.0-327.36.1.el7.x86_64 which IS vulnerable. Red Hat recommends that you update your kernel. Alternatively, you can apply partial mitigation described at https://access.redhat.com/security/vulnerabilities/2706661
Fortunately, applying the fix is straightforward: update your system and reboot your server.
Update and upgrade your packages using
- sudo apt-get update && sudo apt-get dist-upgrade
Note: On older versions of Ubuntu, like 14.04, you’ll also need to select the DigitalOcean GrubLoader kernel. To do this, go to the control panel, click on the server you want to update. Then, click Kernel in the menu on the left and choose the GrubLoader kernel.
Finally, you’ll need to reboot your server to apply the changes.
- sudo reboot
Right now, we’re still waiting on a fix for CentOS 5 and 6. In the interim, you can use this workaround from the Red Hat bug tracker.
To update your kernel on CentOS 7, run:
- sudo yum update
Then, reboot your server.
- sudo reboot
Make sure to update your Linux servers to stay protected from this privilege escalation bug.