First things first, chances are good that your Mac is not at risk in the first place. Want to check?
- Go to the Apple menu, select About This Mac
- Click the System Report… button
- Click the Hardware title in the sidebar
In the Hardware Overview section (it’s relatively short), look for the term hyper-threading. Don’t see it? You can ignore this issue.
If your Mac does support hyper-threading, you should take a look at this official Apple Support document.
Before you take any action, note:
Testing conducted by Apple in May 2019 showed as much as a 40 percent reduction in performance with tests that include multithreaded workloads and public benchmarks. Performance tests are conducted using specific Mac computers. Actual results will vary based on model, configuration, usage, and other factors.
And:
Although there are no known exploits affecting customers at the time of this writing, customers who believe their computer is at heightened risk of attack can use the Terminal app to enable an additional CPU instruction and disable hyper-threading processing technology, which provides full protection from these security issues.
No known exploits. Just the potential for exploits. Forewarned is forearmed.
A bit of a PR ding for Apple, but a mighty issue for Intel.
UPDATE: There is some question as to whether lack of hyper-threading support puts your Mac in safe harbor from the Intel vulnerability. The issue is, if you disable hyper-threading (and add that extra CPU instruction), you’ll be safe. But the question is, if your Mac doesn’t support hyper-threading in the first place, does that mean your Mac is not susceptible to the issue?
If anyone knows the definitive answer to this, please reach out.
If Apple really is planning a move to ARM, this is likely to turn out as a positive for them rather than a ding.
The instructions to check in the System Report don’t work in all circumstances (I appreciate you’ve just reprinted Apple’s own instructions). When I look at the Hardware Overview on my iMac (running Mojave 10.14.4), there’s no mention of hyper-threading.
If I run “sysctl hw.physicalcpu hw.logicalcpu” in the terminal it tells me I have 4 physical cpu cores and 8 logical cpu cores, which suggests hyper-threading is running.
My processor is a Core i7-6700K – if I look that up on Intel’s website, it tells me it supports hyper-threading. Or have Apple only added the hyper-threading details to the system report in 10.14.5, which I haven’t upgraded to yet?
It looks like Apple have updated the system report in 10.14.5 to show whether hyper-threading is enabled or disabled, so the above instructions only work on 10.14.5
I’m not too worried, given that the biggest attack surface is the web, and the browser mitigation is automatic and zero-impact.
(Having skimmed the whitepaper, I am still not too worried for desktop applications.
The server farm guys at Amazon and Google and Microsoft are gonna have conniptions … and are updating all their linux kernels today, I bet.)
Yes and no.
I don’t believe ARM is Magically Immune to speculative attacks as a class (indeed, a quick search shows it is not).
But if Apple puts their mind to it, they can pre-harden from Intel’s lessons, which is nice enough.
Well, what do I know? But I did just disabled the mess on my MacBook Pro. I’m ready for Apple to use their own processor, whatever that will be. ARM? That Apple’s?
Oh, I didn’t mean to imply otherwise. But if Apple can ship a Mac with an ARM chip that is hardened, they’ll be able to “say no Mac with an ARM chip is vulnerable to this particular attack” for various attacks in the future. That’ll be something valuable in a transition.
That’s assuming we get a transition, and it’s a chip swap not a coprocessor. Neither of which I’m 100% sold on.
No. ARM first made its appearance in the Archimedes series of advanced computers in the 80s, but in modified form has been in continuous use ever since, mostly in smartphones and tablets.