Filtered for recent computer exploits

10.54, Tuesday 16 Jan 2018


Recents hacks are about finding holes in the deep physics of computing.

Here’s a technical explanation of Spectre and Meltdown, the two recent big ones. The words alone are beautiful: Spectre can be thought of as a (previously unknown) fundamental risk of speculative execution, one that can now be weaponized.

Here’s a metaphor explaining both exploits, to do with librarians. In short, they involve measuring how long it takes for the computer to look up hidden data. Even if the data is eventually not shared, the computer has a terrible poker face.

I see this as a kind of information asymmetry. Computer chip architecture is about the regulated control of information. The design never anticipated that unregulated information - time - would be brought in from the outside.

See also: Rowhammer, which is an exploit of how memory chips work where the wild information, intruding from the outer reality, is electromagnetism and geography.

As DRAM manufacturing scales down chip features to smaller physical dimensions, to fit more memory capacity onto a chip, it has become harder to prevent DRAM cells from interacting electrically with each other. As a result, accessing one location in memory can disturb neighbouring locations, causing charge to leak into or out of neighbouring cells. With enough accesses, this can change a cell’s value from 1 to 0 or vice versa.

That is, the fact that two memory address happen to be physically close to one another is completely outside the computer’s knowledge of itself. Geography and electromagnetism have no presence in the computer’s inner reality. But bring that knowledge in from the outer reality…

Rowhammer was able to use this to induce bit flips … and hence gain read-write access to all of physical memory.


Long profile in the New Yorker of Sam Altman, the head of Y Combinator (the incubator behind startups such as Airbnb, Dropbox, Stripe, and reddit).

This line:

Many people in Silicon Valley have become obsessed with the simulation hypothesis, the argument that what we experience as reality is in fact fabricated in a computer; two tech billionaires have gone so far as to secretly engage scientists to work on breaking us out of the simulation.

Emphasis mine.


Here’s an interesting exploit that I feel should be better known: System Bus Radio.

Some computers are intentionally disconnected from the rest of the world. This includes having their internet, wireless, bluetooth, USB, external file storage and audio capabilities removed. This is called “air gapping”. [However] Even in such a situation, this program can transmit radio.

Computers can now write to memory with a high enough frequency that it’s in the radio spectrum. Now you’re hitting the RAM fast enough, you can play it like a xylophone and carve radio waves into the air.

There is demo code provided. And:

Run this using a 2015 model MacBook Air. Then use a Sony STR-K670P radio receiver with the included antenna and tune it to 1580 kHz on AM.

You should hear the “Mary Had a Little Lamb” tune playing repeatedly.

So what happens when my mobile web browser loads an ad that loads some Javascript that reads my bitcoin exchange password and then runs tight array loops that hammer out arpeggios on memory, broadcasting access to all my worldly possessions to anyone standing nearby with a old-fashioned AM radio tuned into 1580 kHz?

Breaking out of the simulation.


By volume, the Sun produces about the same amount of heat as a reptile.

Also the average density of the Sun is 1,410 kg per cubic meter: 1.4x that of water. Or to put it another way, the same as honey.

So yeah. The Sun. A million times bigger than the Earth. As hot as a reptile. As thick as honey.

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