VMware has been disabling their inter-VM memory deduplication (TPS) since 6.0 to avoid exactly these kinds of attacks. You can of course re-enable it, if you want, and I've seen situations where its value far outpaced the potential risk.
It also looks like ECC greatly reduces the potential for this to be exploited.
set 0 to stop ksmd from running but keep merged pages,
set 1 to run ksmd e.g. "echo 1 > /sys/kernel/mm/ksm/run",
set 2 to stop ksmd and unmerge all pages currently merged,
but leave mergeable areas registered for next run
Default: 0 (must be changed to 1 to activate KSM,
except if CONFIG_SYSFS is disabled)
That's not what the article says. The article says that with a specific attack, one can change memory bits in running applications to which one should not have access. This application could be a VM, or any other type of application.
This is a pretty sophisticated attack requiring a lot of stuff to fall into place (such as being provisioned on the same machine as the target), and even though it is technically quite impressive I doubt it is a frequent enough occurrence that you could conclude that if you host on a shared machine you're going to get hacked sooner or later.
The chances of being hacked through some simpler and more direct vector are a lot larger.
Right, it's probably TLAs that will use this most heavily. But they typically have so many targets that this will be fully automated. Gotta get that network access, bro.
On-premise, with or without VMs, does not safe you from rowhammer, however. That's just another use case, and not really surprising. Since you can modify RAM, there aren't borders really.
At least one of the big hosters even lets you have VMs for free for a couple of days (you get your money back if you cancel). That's more than enough time for an automated process to check out tons of VMs (to add to your botnet) for free.
the timing isn't a coincidence. cloud infrastructure is becoming a high-value target for security researchers and cybercriminals precisely because organizations are moving sensitive data into the cloud.
to be clear: i don't mean to lump security researchers and cybercriminals into a common group. it just so happens that they both have motivating interests in this industry shift.
It also looks like ECC greatly reduces the potential for this to be exploited.