What is Spectre?

Spectre is not a physical problem with the CPUs themselves, or a plain software bug you might find in an application like Word or Chrome. It’s in between, at the level of the processors’ “architectures,” the way all the millions of transistors and logic units work together to carry out instructions.

In modern architectures, there are inviolable spaces where data passes through in raw, unencrypted form, such as inside the kernel, the most central software unit in the architecture, or in system memory carefully set aside from other applications. This data has powerful protections to prevent it from being interfered with or even observed by other processes and applications.

Spectre affects Intel, AMD, and ARM processors, broadening its reach to include mobile phones, embedded devices, and pretty much anything with a chip in it. Which, of course, is everything from thermostats to baby monitors now.

Spectre essentially tricks applications into accidentally disclosing information that would normally be inaccessible, safe inside their protected memory area. This is a trickier one to pull off, but because it’s based on an established practice in multiple chip architectures, it’s going to be even trickier to fix.