>even a cosmic ray flipping the "do not upload" bit in memory
Stats on this very likely scenario?
Stats on this very likely scenario?
From the wikipedia article on "Soft error", if anyone wants to extrapolate.
So roughly you could expect this happen roughly once every two hundred million years.
Assuming there are about 2 billion Windows computers in use, that’s about 10 computers a year that experience this bit flip.
That's wildly more than I would have naively expected to experience a specific bit-flip. Wow!
Big numbers are crazy.
But it was quite amusing to see in my own eyes: computer mostly worked fine but occasionally would cry what "Can't load library at C:\WINDOWS\system33\somecorewindowslibrary.dll".
I didn't even notice at first just though it was a virus or a consequences of a virus infection until I caught that '33' thing. Gone to check and there were system32, system33, system34...
So when the computer booted up cold at the morning everything were fine but at some time and temp the unstable cell in the RAM module started to fluctuate and mutate the original value of a several bits. And looks like it was in a quite low address that's why it often and repeatedly was used by the system for the same purpose: or the storage of SystemDirectory for GetSystemDirectory or the filesystem MFT.
But again, it's the only time where I had a factual confirmation of a memory cell failure and only because it happened at the right (or not so, in the eyes of the user of that machine) place. How many times all these errors just silently go unnoticed, cause some bit rot or just doesn't affect anything of value (your computer just froze, restarted or you restarted it yourself because it started to behave erratically) is literally unknown - because that's is not a ECC memory.
More on the topic: Single-event upset[1]
That's all errors including permanent hardware failure, not just transient bit flips or from cosmic rays.
"We provide strong evidence that memory errors are dominated by hard errors, rather than soft errors, which previous work suspects to be the dominant error mode." [0]
"Memory errors can be caused by electrical or magnetic interference (e.g. due to cosmic rays), can be due to problems with the hardware (e.g. a bit being permanently damaged), or can be the result of corruption along the data path between the memories and the processing elements. Memory errors can be classified into soft errors, which randomly corrupt bits but do not leave physical damage; and hard errors, which corrupt bits in a repeatable manner because of a physical defect."
"Conclusion 7: Error rates are unlikely to be dominated by soft errors.
We observe that CE [correctable errors] rates are highly correlated with system utilization, even when isolating utilization effects from the effects of temperature. In systems that do not use memory scrubbers this observation might simply reflect a higher detection rate of errors. In systems with memory scrubbers, this observations leads us to the conclusion that a significant fraction of errors is likely due to mechanism other than soft errors, such as hard errors or errors induced on the datapath. The reason is that in systems with memory scrubbers the reported rate of soft errors should not depend on utilization levels in the system. Each soft error will eventually be detected (either when the bit is accessed by an application or by the scrubber), corrected and reported. Another observation that supports Conclusion 7 is the strong correlation between errors in the same DIMM. Events that cause soft errors, such as cosmic radiation, are expected to happen randomly over time and not in correlation.
Conclusion 7 is an interesting observation, since much previous work has assumed that soft errors are the dominating error mode in DRAM. Some earlier work estimates hard errors to be orders of magnitude less common than soft errors and to make up about 2% of all errors."
[0] https://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf
Was in DEFCON19.
Can't find an explanatory video though :(
Also, around 1999-2000, Sun blamed cosmic rays for bit flips for random crashes with their UltraSPARC II CPU modules.
Yep, hardware failures, electrical glitches, EM interference... All things that actually happen to actual people every single day in truly enormous numbers.
It ain't cosmic rays, but the consequences are still flipped bits.