WEBVTT 00:00:00.030 --> 00:00:05.160 thanks for watching Techquickie click the subscribe button then enable 00:00:03.210 --> 00:00:10.400 notifications with the Bell icon so you won't miss any future videos when 00:00:07.680 --> 00:00:15.630 Spector and meltdown first made headlines you'd have been 00:00:13.170 --> 00:00:20.939 forgiven for thinking that dr. no found a way to cause mayhem at a nuclear power 00:00:18.029 --> 00:00:25.560 plant somewhere but while thankfully that isn't what happened The Spectre and 00:00:23.189 --> 00:00:30.929 meltdown security bugs have the potential to inflict ma'am on nearly 00:00:27.689 --> 00:00:33.960 every computer in the world between them 00:00:30.929 --> 00:00:36.480 you see most software bugs and viruses 00:00:33.960 --> 00:00:42.149 affect systems by trying to exploit some weakness in the code of a particular 00:00:38.820 --> 00:00:44.309 program or operating system meaning that 00:00:42.149 --> 00:00:49.649 they can't hurt a system they weren't designed to run on what makes spectre 00:00:46.890 --> 00:00:55.500 and meltdown so dangerous is that they function on a level that is much closer 00:00:52.110 --> 00:00:58.559 to the actual hardware meaning that they 00:00:55.500 --> 00:01:02.100 can exploit tons of different CPU models 00:00:58.559 --> 00:01:04.979 and operating systems in fact meltdown 00:01:02.100 --> 00:01:13.049 affects nearly every Intel CPU manufactured since 1995 and specter 00:01:09.060 --> 00:01:13.640 effects these and most AMD processors as 00:01:13.049 --> 00:01:18.360 well Spectre clasp vulnerabilities can even 00:01:16.470 --> 00:01:27.240 successfully attack a number of smartphone CPUs holy crap so what 00:01:23.520 --> 00:01:28.700 happened why exactly are these bugs so 00:01:27.240 --> 00:01:34.650 widespread well it boils down to a feature present 00:01:32.310 --> 00:01:41.130 on virtually all modern processors called speculative execution which is a 00:01:37.829 --> 00:01:43.829 key way that CPU significantly boosts 00:01:41.130 --> 00:01:50.100 their performance thanks to speculative execution when a CPU is carrying out 00:01:46.560 --> 00:01:51.960 program instructions it can guess which 00:01:50.100 --> 00:01:58.500 instructions it might have to process next allowing a modern processor to read 00:01:55.680 --> 00:02:03.540 ahead on the page so to speak processing data that it thinks it will need shortly 00:02:00.570 --> 00:02:10.289 and then storing it on the very fast CPU cache memory one way that CPUs read 00:02:07.170 --> 00:02:13.180 ahead is by starting to process the data 00:02:10.289 --> 00:02:17.500 in memory as soon program asks for it rather than first checking to see if 00:02:15.519 --> 00:02:22.330 that program is even allowed to access that data you see whenever you have more 00:02:20.080 --> 00:02:27.510 than one program running your CPU will separate your system RAM into different 00:02:25.030 --> 00:02:33.280 chunks that can only be accessed by one program to keep other ones including 00:02:30.700 --> 00:02:38.410 malicious programs from seeing data that they shouldn't so let's say then that 00:02:35.590 --> 00:02:44.530 program a asks to see some data from program B's memory space the CPU will 00:02:41.290 --> 00:02:46.959 say no but only after it starts to read 00:02:44.530 --> 00:02:52.390 that memory and whatever was in that memory space is already in the CPUs 00:02:49.420 --> 00:02:58.090 cache now although the CPU won't directly pass that data at a program a 00:02:54.900 --> 00:03:01.329 meltdown can figure out what the data is 00:02:58.090 --> 00:03:03.970 by tricking the CPU instead of just 00:03:01.329 --> 00:03:09.760 asking for the data directly meltdown will ask the CPU to add the value being 00:03:07.329 --> 00:03:16.090 held in cache to some arbitrary number which will correspond to a certain 00:03:12.190 --> 00:03:18.430 memory location or address the CPU still 00:03:16.090 --> 00:03:23.730 won't reveal the information at that memory address to meltdown directly but 00:03:20.980 --> 00:03:28.959 the data will still be cached beforehand so I know this is pretty technical here 00:03:25.989 --> 00:03:34.389 but stick with me for its next trick meltdown will ask the CPU to read more 00:03:31.930 --> 00:03:38.349 memory addresses noting the one that loads more quickly than the others 00:03:36.519 --> 00:03:44.319 because it was stored in the high-speed cache in the previous step rather than 00:03:41.139 --> 00:03:47.169 the slower system RAM this process 00:03:44.319 --> 00:03:52.510 allows meltdown to figure out what data was in the address it initially asked 00:03:49.750 --> 00:03:57.400 for as the cached address will just be whatever the arbitrary number that 00:03:54.400 --> 00:03:59.430 meltdown picked plus the actual value 00:03:57.400 --> 00:04:04.299 the system was trying to keep hidden was let's move on to Spector now although 00:04:02.049 --> 00:04:08.680 Spector also takes advantage of speculative execution it works a little 00:04:06.639 --> 00:04:13.660 bit differently by exploiting a CPUs branch predictor this processor 00:04:11.260 --> 00:04:18.729 component watches for patterns in program execution so if it sees a 00:04:15.940 --> 00:04:23.620 particular function over and over again the CPU will eventually pick up on it 00:04:21.459 --> 00:04:26.710 and start to process this function on its own repeatedly 00:04:25.180 --> 00:04:32.560 like how you can train your pet to do tricks by giving it food every time so 00:04:29.650 --> 00:04:36.699 Spectre trains your CPU by telling it over and over to execute instructions 00:04:35.050 --> 00:04:42.370 that will dump the information the attacker wants into cash after this 00:04:39.660 --> 00:04:47.860 Specter can access the information by using various timing tricks to work out 00:04:44.860 --> 00:04:50.350 exactly what the data contains sometimes 00:04:47.860 --> 00:04:55.270 by asking the CPU to use the data located at a certain memory address in a 00:04:52.930 --> 00:04:59.789 different function similarly to meltdown and getting back to why this problem is 00:04:58.570 --> 00:05:05.110 so widespread Spectre is a whole class of attacks 00:05:02.800 --> 00:05:09.310 which means combined with the fact that branch prediction is incredibly 00:05:07.330 --> 00:05:15.509 important for performance in nearly all modern CPUs means that there isn't a 00:05:12.729 --> 00:05:20.770 quick fix for every variation of it meltdown by contrast is a somewhat 00:05:18.310 --> 00:05:27.099 easier fix that involves more thoroughly separating different memory spaces but 00:05:23.620 --> 00:05:29.349 since the patches also cut into a CPUs 00:05:27.099 --> 00:05:34.150 ability to read ahead as we described earlier the fixes can result in serious 00:05:32.110 --> 00:05:39.340 slowdowns for processor intensive programs as current CPUs have actually 00:05:36.940 --> 00:05:45.490 gotten really good at predicting what they'll need to do next a sad irony now 00:05:42.940 --> 00:05:50.020 both Intel and AMD are working to fix the vulnerabilities on a hardware level 00:05:47.680 --> 00:05:55.690 in their future chips which is certainly good news but because speculative 00:05:53.199 --> 00:06:01.389 execution is so fundamental to modern CPU design only time will tell if even 00:05:58.960 --> 00:06:07.330 brand-new processors can actually plug these holes for good and obviously that 00:06:05.380 --> 00:06:14.199 solution isn't going to do anything for the literally billions of CPUs that are 00:06:11.080 --> 00:06:16.840 already out in the wild so yes this 00:06:14.199 --> 00:06:22.780 means you Jeff from New York proud owner of an overclocked 46 70 K unless you 00:06:19.990 --> 00:06:26.949 want to go buy new hardware all you can really do is be careful what you click 00:06:24.370 --> 00:06:31.060 on out there a cleverly designed attack that takes advantage of specter warm 00:06:28.870 --> 00:06:35.110 meltdown 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