3 ms·

I have no idea how or if this is a big deal but: >>attack that would be almost expected in a processor with speculative execution unless special measures were

I have no idea how or if this is a big deal but: >>attack that would be almost expected in a processor with speculative execution unless special measures were taken to prevent it. if you're going to put in features with expected attacks you should definitely be putting in features to prevent it , and if it is an expected attack it shouldn't be special measures it should just be an inherent part in introducing the feature.

userbinator 9y ago
When speculative execution (and caches) were invented and put into widespread use, no one thought about timing attacks, nor was the practice of running untrusted code on one's own machine common.
- im3w1l 9y ago
  UNIX has been multi-user for a very long time and the intended use case is that those users not be able to compromise each other or get root.
- nitrogen 9y ago
  nor was the practice of running untrusted code on one's own machine common Doesn't multi-user timesharing and virtualization predate every modern CPU and OS though?
  - SAI_Peregrinus 9y ago
    Yes, but it went out of style for a while. At first, computers were very expensive, and so were shared between many users. Mainframes, UNIX, dumb terminals, etc. Then computers became cheap. Users could each have their own computer, and simply communicate with a server. Each business could have their own servers co-located in a datacenter. Then virtualization got really good, and suddenly cloud servers became viable. You didn't have to pay for a whole server all the time, and if demand rapidly increased you didn't need to buy lots of new hardware. And if demand decreased you didn't get stuck with tons of useless hardware. The second stage (dedicated servers) was the case when speculative execution was implemented. We're currently in the third stage, but Intel haven't changed their designs.
  - pixl97 9y ago
    Old multi-user time sharing generally had agents that were 'somewhat' trusted. Most systems that had 'secret' data didn't allow time sharing with data of less privileged. Also, outside of the timeshared server users attempting to exploit this wouldn't likely have the processing capability to deduce the contents of said cache.

userbinator 9y ago

When speculative execution (and caches) were invented and put into widespread use, no one thought about timing attacks, nor was the practice of running untrusted code on one's own machine common.

im3w1l 9y ago
UNIX has been multi-user for a very long time and the intended use case is that those users not be able to compromise each other or get root.
nitrogen 9y ago
nor was the practice of running untrusted code on one's own machine common Doesn't multi-user timesharing and virtualization predate every modern CPU and OS though?
- SAI_Peregrinus 9y ago
  Yes, but it went out of style for a while. At first, computers were very expensive, and so were shared between many users. Mainframes, UNIX, dumb terminals, etc. Then computers became cheap. Users could each have their own computer, and simply communicate with a server. Each business could have their own servers co-located in a datacenter. Then virtualization got really good, and suddenly cloud servers became viable. You didn't have to pay for a whole server all the time, and if demand rapidly increased you didn't need to buy lots of new hardware. And if demand decreased you didn't get stuck with tons of useless hardware. The second stage (dedicated servers) was the case when speculative execution was implemented. We're currently in the third stage, but Intel haven't changed their designs.
- pixl97 9y ago
  Old multi-user time sharing generally had agents that were 'somewhat' trusted. Most systems that had 'secret' data didn't allow time sharing with data of less privileged. Also, outside of the timeshared server users attempting to exploit this wouldn't likely have the processing capability to deduce the contents of said cache.