ARCHER Webinar: Meltdown for Dummies
Channel: ARCHER UK National Supercomputing Service
Date: 30/03/2018

Meltdown for Dummies: The road to hell is paved with good intentions 

David Henty, EPCC

The history of IT security seems littered with tales of apocalyptic vulnerabilities that would end the world - does your Heart Bleed at the mention of the Y2K bug? However, the recent scares over Meltdown were based on a really big problem:

ANY user could read ANY memory on almost ANY system, bypassing ALL security measures.

In this webinar I will try and explain the origin of Meltdown from a dummy's point of view (i.e. my own). I will use an everyday analogy of accessing documents from a lawyer's office to illustrate the origins of the vulnerability and how it can be exploited. I will also present results of recent tests exploring how much the anti-Meltdown patches affect HPC system performance.

Meltdown is an extremely interesting example as, to understand it, you need to understand a wide range of issues covering both CPU hardware and system software design. Even if you're not that concerned with IT security, I hope that this presentation will help explain how modern multi-user computers actually work.

Most importantly, I hope to show that the design decisions that led to Meltdown all seem perfectly sensible in themselves. However, as Saint Bernard of Clairvaux wrote in the early 12th century, "the road to hell is paved with good intentions".