Patching your AWS EC2 instance for the Meltdown/Spectre vulnerabilities


The patches we will be applying bring the KPTI (kernel page-table isolation), a Linux kernel feature that mitigates the Meltdown security vulnerability. The title of this post is therefore a misnomer - there are no Spectre patches yet, but by convention all three known variants of these vulnerabilities are jointly referred to as Meltdown/Spectre. I will update this post when this changes.

Updating the instance with the patched kernel

I will describe the steps based on AWS instance running Ubuntu 14.04.5 LTS and GNU/Linux 4.4.0-97-generic kernel prior to applying the patch.

The most up-to-date information on Spectre and Meltdown for Ubuntu can be found here: It also contains recommended kernel images for various distro versions.

Step 1) SSH into your instance:


Update the repositories:

sudo apt-get update

As of writing this post Canonical recommends kernel image 3.13.0-139.188 for Ubuntu 14.04 using 3.13 and 4.4.0-109.132 if you are using the xenial kernel backport (4.4.0), so let’s install those:

sudo apt-get install linux-headers-4.4.0-109 linux-headers-4.4.0-109-generic linux-image-4.4.0-109-generic linux-image-extra-4.4.0-109-generic --fix-missing

Step 2) reboot you instance

You can quickly reboot an instance using the command line if you have configured AWS CLI:

aws ec2 reboot-instances --instance-ids instance-id --region region

or with the EC2 console.

  1. Open the Amazon EC2 console.
  2. In the navigation pane, choose Instances.
  3. Select the instance and choose Actions, Instance State, Reboot.
  4. Choose Yes, Reboot when prompted for confirmation.

Step 3) so did it work?

Check if the instance is back online:

aws ec2 describe-instance-status --instance-id instance-id --region region

SSH to it and you can use this (script) which does a wonderful job at checking the kernel susceptibility to all known variants of Spectre/Meltdown:

chmod a+x
sudo ./

You should see something similar to the screenshot below:


Written on January 11, 2018