Protect Your Server Against the Dirty COW Linux Vulnerability

Check Vulnerability

Ubuntu/Debian

To find out if your server is affected, check your kernel version.

uname -rv

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

CentOS

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.

  • bash rh-cve-2016-5195_1.sh

If you’re vulnerable, you’ll see output like this:

Output
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 .

Fix Vulnerability

Fortunately, applying the fix is straightforward: update your system and reboot your server.

On Ubuntu and Debian, upgrade your packages using apt-get.

  • sudo apt-get update && sudo apt-get dist-upgrade

You can update all of your packages on CentOS 5, 6, and 7 with sudo yum update, but if you only want to update the kernel to address this bug, run:

  • sudo yum update kernel

Finally, on all distributions, you’ll need to reboot your server to apply the changes.

  • sudo reboot
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