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this leads me to a couple questions, hopefully you smart folk can answer: 1. I thought Spectre was "Intel-only", and Meltdown was the general case, which is le
by 2bitencryption 9y ago
this leads me to a couple questions, hopefully you smart folk can answer:
1. I thought Spectre was "Intel-only", and Meltdown was the general case, which is less severe but effectively nearly everywhere? If so, how is an iPhone susceptible to Spectre?
2. Beyond that, I thought meltdown/spectre was an x86 problem. So why all this trouble on phones, with ARM?
3. I've read the first, simplest variant of meltdown, and it is so beautifully simple. Is this "speculative execution + cache timing" thing an entirely novel exploit, or have we seen incarnations of this before?
- deleted 9y ago[deleted]
- Scaevolus 9y ago1. is reversed: meltdown is intel-only. Spectre is a more generic speculation attack. 2. Apple's custom ARM chips have extensive speculative execution, and clearly their fixes for it are extremely expensive. 3. It's novel, which is why security researchers are so excited! Branching based side-channel attacks were previously only known to be able to track execution (so branch-based AES encryption was vulnerable to having its keys stolen)-- but reading arbitrary data is much stronger.
- qeternity 9y agoRe: #2 - it’s a speculative execution issue, not x86 specific.
- deleted 9y ago[deleted]
- JoachimSchipper 9y ago1: Spectre is the general case, Meltdown is the Intel-only evil cousin. 2: Spectre applies to all modern processors with speculative execution, which includes smartphone-class ARM processors. Raspberry Pi's and microprocessors ("toasters") are not affected. 3: There's some prior work - Spectre didn't fall from thin air - but using speculative execution as the basis of an exploit makes Spectre the first bugs in, I believe, a new class. (Meltdown, on the other hand, is just a silly mistake that shouldn't be repeated.)