#1938: Meltdown and Spectre explain

[Zoom out with Cueball and Ponytail walking to the right on the ground.]

Cueball: The Meltdown and Spectre exploits use “speculative execution?” What’s that?

Ponytail: You know the trolley problem? Well, for a while now, CPUs have basically been sending trolleys down both paths, quantum-style, while awaiting your choice. Then the unneeded “phantom” trolley disappears.

[Zoom in on only Ponytail who has turned towards Cueball off-panel left.]

Ponytail: The phantom trolley isn’t supposed to touch anyone. But it turns out you can still use it to do stuff.

Ponytail: And it can drive through walls.

[Cueball and Ponytail, lifting both her palms up, are standing, facing each other.]

Cueball: That sounds bad.

Ponytail: Honestly, I’ve been assuming we were doomed ever since I learned about Rowhammer.

[In a frame-less panel they continue talking, both with their arms down.]

Cueball: What’s that?

Ponytail: If you toggle a row of memory cells on and off really fast, you can use electrical interference to flip nearby bits and—

Cueball: Do we just suck at…computers?

Ponytail: Yup. Especially shared ones.

[Zoom out again as they resume walking to the right on the ground. Cueball is lifting his smartphone up and looks at the screen.]

Cueball: So you’re saying the cloud is full of phantom trolleys armed with hammers.

Ponytail: …Yes, that is exactly right.

Cueball: Okay. I’ll, uh… install updates?

Ponytail: Good idea.