Both are triggered by malicious code running on the same hardware as you.
Mitigation means don't put anything important on shared hardware (read: avoid VPSes) and run NoScript or the equivalent in your browser.
Weren't those security best practices already?
Yes, this is a nightmare for VPS providers and worrying for those who placed their trust in virtualization. But the tinfoil-hat brigade has been assuming such bugs existed for ages.
Am I missing anything?
@paco The security best practice I speak of is:
"Don't share hardware with untrusted strangers who can run arbitrary code and try to attack your hypervisor or local network."
Of course you should use all the compartmentalization tech that is appropriate for your use case. Even if they can be attacked, it raises the bar.
@HerraBRE Never share hardware with strangers? Seems too blunt.
At face value that would prevent using any cloud infrastructure at all wouldn't it? Seems like it might make SaaS services problematic too.
I don't think I've seen that sort of principle put forward as a best practice. I don't see how you could follow that principle in 2018.
@rysiek @HerraBRE The date on this advisory is yesterday, and note that at that time 90+% were already done worldwide. Who patches faster than that? https://aws.amazon.com/security/security-bulletins/AWS-2018-013/
There will be more bugs like this.
Security professionals know this and have known for a long time. Thus my claim it was a standard best practice, albeit one that has costs not everyone could justify.
That math has shifted now, more people will justify the expense. Not all, but more.