Hardware bugs: Meltdown and Spectre

One man’s bug is another man’s feature.

  • Meltdown affects effectively every Intel processor (unknown whether ARM and AMD are affected).
  • Spectre affects Intel, AMD, and ARM processors.
  • Cloud providers relying on containers that share one kernel, such as Docker, LXC, or OpenVZ are affected.



Meltdown breaks the most fundamental isolation between user applications and the operating system. This attack allows a program to access the memory, and thus also the secrets, of other programs and the operating system.

If your computer has a vulnerable processor and runs an unpatched operating system, it is not safe to work with sensitive information without the chance of leaking the information. This applies both to personal computers as well as cloud infrastructure. Luckily, there are software patches against Meltdown.


Spectre breaks the isolation between different applications. It allows an attacker to trick error-free programs, which follow best practices, into leaking their secrets. In fact, the safety checks of said best practices actually increase the attack surface and may make applications more susceptible to Spectre

Spectre is harder to exploit than Meltdown, but it is also harder to mitigate. However, it is possible to prevent specific known exploits based on Spectre through software patches.

There are VMware and other hypervisor security advisories https://lists.vmware.com/pipermail/security-announce/2018/000397.html . https://xenbits.xen.org/xsa/advisory-254.html


and Why Raspberry Pi isn’t vulnerable to Spectre or Meltdown

Modern processors go to great lengths to preserve the abstraction that they are in-order scalar machines that access memory directly, while in fact using a host of techniques including caching, instruction reordering, and speculation to deliver much higher performance than a simple processor could hope to achieve. Meltdown and Spectre are examples of what happens when we reason about security in the context of that abstraction, and then encounter minor discrepancies between the abstraction and reality.

The lack of speculation in the ARM1176, Cortex-A7, and Cortex-A53 cores used in Raspberry Pi render us immune to attacks of the sort.