Hertzbleed Attack

Post by lostmsu » Wed, Jun 15, 2022, 12:21 AM UTC

_0w8t wrote: post #180

ancientsofmumu wrote: post #152

This paper relies on Turbo P-states, where they measure the oscillation when that is active; it is not measuring general SpeedStep (OS software controlled) as some seem to have taken away from it. Turbo state is the HWP (hardware P-state controlled) layer above SpeedStep; turning off Turbo in the BIOS still fully allows OS controlled SpeedStep P-states to function, it just disables the hardware level bursting P-state…

On MacOS Low-Power mode in the Power section of system settings disables turbo-boost. On Linux echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo does the rick. Note that this is not the same as power-saving mode in Gnome settings. I have found that for heavy C++ compilation that lasts for many minutes the slowdown was about 20% on my ThinkPad X1 laptop. The big plus is that it made the laptop almost silent.

Post by samstave » Wed, Jun 15, 2022, 12:26 AM UTC

saagarjha wrote: post #237

samstave wrote: post #230

Earlier quoted context omitted.

Quoted post unavailable.

Being unnecessarily cryptic and sounding like a crackpot while calling everyone else out for being uninformed is generally unlikely to get you support on Hacker News.

Post by iratewizard » Wed, Jun 15, 2022, 12:31 AM UTC

kelnos wrote: post #270

selcuka wrote: post #264

Earlier quoted context omitted.

> they relied on so much detailed information about the environment being attacked A disgruntled, previous employee may easily have access to such information, but nothing else because their credentials had been disabled.

I think you overestimate what kind of information most employees -- even those who build the software that runs on their servers -- have about their execution environments.

Post by userbinator » Wed, Jun 15, 2022, 12:31 AM UTC

simias wrote: post #170

FartyMcFarter wrote: post #169

> This means that, on modern processors, the same program can run at a different CPU frequency (and therefore take a different wall time) when computing, for example, 2022 + 23823 compared to 2022 + 24436. I'm not a hardware expert, and I was a bit surprised at this. Is that because the transistors heat up more with certain input values, which then results in a lower frequency when the CPU gets hot enough? Something…

Not an expert either but number of cycles is not everything, transistors that transition use up more energy than those who remain in the same state. As such it's possible that 0x00000000 + 1 uses up significantly less energy than 0xffffffff + 1, just because of all the bit flips. That's just a guess though.

Post by nmilo » Wed, Jun 15, 2022, 1:17 AM UTC

velcrovan wrote: post #85

kzrdude wrote: post #75

Earlier quoted context omitted.

You can say the same thing about all of these attacks. That they are tedious ways of collecting data. The problem is that computers can be made to repeat operations, over and over again. Leaking keys fractional bit by bit or what it is. That's why the attack doesn't work against someone's laundry machine - unless it's connected to the internet, that is.

This is the kind of exploit that might legitimately warrant the character-by-character “password slot machine” animation from movies like “War Games” ( https://tvtropes.org/pmwiki/pmwiki.php/Main/PasswordSlotMach... )