I have a very vague understanding of all of these DDR bitflip attacks, but I found the original Hammertime paper and it's actually very easy to read. I haven't gone through all of it but it breaks things down to be better understood very well.
I've heard bitflipping a million times and never really got it (not that I made serious effort) until this.
I feel like I just went through a 101 EE course. I had NO idea any of this was related to the actual hardware manufacturing imperfections, etc.
That explains the name Rowhammer. I've probably been under a rock and everyones knows this stuff.
> Due to the extreme density of modern DRAM arrays, small manufacturing imperfections can cause weak electrical coupling between neighboring cells. This,
combined with the minuscule capacitance of such cells, means that every time a
DRAM row is read from a bank, the memory cells in adjacent rows leak a small
amount of charge. If this happens frequently enough between two refresh cycles,
the affected cells can leak enough charge that their stored bit value will “flip”,
a phenomenon known as “disturbance error” or more recently as Rowhammer.
> Due to the extreme density of modern DRAM arrays, small manufacturing imperfections can cause weak electrical coupling between neighboring cells.
This makes it sound like it's unavoidable and inherent to making DRAM. It isn't.
DRAM manufacturers have been pushing the limits to an extreme. That's why. Pursuit of profit. This is no different from Ford deciding the cost of settling Pinto lawsuits (from injuries and deaths) was less than the cost of fixing the car's design.
I've heard bitflipping a million times and never really got it (not that I made serious effort) until this.
https://comsec.ethz.ch/wp-content/files/hammertime_raid18.pd...
I feel like I just went through a 101 EE course. I had NO idea any of this was related to the actual hardware manufacturing imperfections, etc.
That explains the name Rowhammer. I've probably been under a rock and everyones knows this stuff.
> Due to the extreme density of modern DRAM arrays, small manufacturing imperfections can cause weak electrical coupling between neighboring cells. This, combined with the minuscule capacitance of such cells, means that every time a DRAM row is read from a bank, the memory cells in adjacent rows leak a small amount of charge. If this happens frequently enough between two refresh cycles, the affected cells can leak enough charge that their stored bit value will “flip”, a phenomenon known as “disturbance error” or more recently as Rowhammer.