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New cloud attack takes full control of virtual machines with little effort

arstechnica.com

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Re: New cloud attack takes full control of virtual machines with little effort

#81

Post by Rezo »

willvarfar wrote: post #63
ploxiln wrote: post #58

Earlier quoted context omitted.

Xen has had page-table and interrupt vector related security vulnerabilities. But I don't think EC2 would use non-ECC RAM, so I don't think it's vulnerable to this "rowhammer" technique. (I also don't think EC2 would do cross-VM page deduplication, another necessary condition.)

Perhaps we need more certainty than just "think"? That AWS don't boast that they are not susceptible to this suggests that perhaps at least some of their setup is?

The EC2 FAQ [0] states:

"In our experience, ECC memory is necessary for server infrastructure, and all the hardware underlying Amazon EC2 uses ECC memory."

While ECC does apparently not completely mitigate Rowhammer, it helps.

[0] https://aws.amazon.com/ec2/faqs/

Re: New cloud attack takes full control of virtual machines with little effort

#82

Post by ultramancool »

acobster wrote: post #79
Dylan16807 wrote: post #60

Earlier quoted context omitted.

Rowhammer is largely random. You don't get to target specific bits of physical ram. You find scarce weak bits and work to get the data located there. In this case that means you can only pick a couple bits per 4KB to attack. That won't let you fake out a CRC.

That's where I'm getting a little hazy. The paper says the attacker can "induce bit flips over arbitrary physical memory in a fully controlled way." Sounds a little more advanced than "largely random" to me, and based on the article it sounds like FFS is a step up from "vanilla" Rowhammer...am I missing something?

Yeah, I mean if it won't beat a CRC wouldn't ECC RAM be a reasonably easy solution to this and wouldn't most servers already be secured against it?

Re: New cloud attack takes full control of virtual machines with little effort

#84

Post by nickpsecurity »

willvarfar wrote: post #52
nickpsecurity wrote: post #15

Earlier quoted context omitted.

There's CPU's that do memory, integrity checking to contain attacks. They're designed for stoping software and peripheral attacks mainly but consider RAM untrusted. They could probably be modified to deal with the new attacks.

Encrypted RAM is offered by the newest Intel server-grade CPUs (SGX, Skylake) and the next AMD server-grade CPUs (SME, Zen). One of the main use-cases for these technologies is trusted computing in a cloud environment - the customer can assert that the hardware is securing the program state from the eyes of the computer owner!. However, the cloud is actually made from cheap commodity boxes without server-grade anythi…

I figured it would end up in security-oriented, bare-metal hosting first. Or racks people rent out for their own boxes. Didn't know something like that was on new Inte/AMD CPU's. Thanks for tip.

Re: New cloud attack takes full control of virtual machines with little effort

#85

Post by micro_softy »

"For the attacks to work, the cloud hosting the VM must have deduplication enabled so that physical pages are shared between customers."

But the vendor's cloud will not disable sharing pages of physical memory because ____.

This is a great counterpoint to the salesman trying to sell you on "cloud" anything.

Why is it less expensive to use the "cloud"?

One reason is because you do not get your own physical server, including your own RAM.

When the "cloud" buzz began to gain momentum years ago I raised the issue of not knowing who your "neighbors" were on these physical servers that customers are sharing with other customers in datacenters.

As usual, these concerns will just fade into the background... again.

Re: New cloud attack takes full control of virtual machines with little effort

#86

Post by nickpsecurity »

tsukikage wrote: post #69
nickpsecurity wrote: post #35

Earlier quoted context omitted.

I know what the root problem is. I also know it comes from an oligopoly of companies that only care about money, probably have patents on key features, and operate in a price-sensitive market. Fixing root cause might be tricky unless you could be sure via contracts of volume deals from cloud and other big buyers. Meanwhile, small teams in academia are building CPU's that knock out those and other issues. Worth bringi…

You can't entirely blame the providers for only caring about money; the consumers that choose the budget hosting options for critical applications must surely share some of it. Server grade hardware is certainly available to cloud/VPS providers, but it turns out people are unwilling to pay $2 for a VM if there's one going elsewhere for $1.50.

"the consumers that choose the budget hosting options for critical applications must surely share some of it."

The customers expect the RAM they bought to work correctly. They might have even read papers on ASIC verification where the hardware companies brag about all these techniques they use to prevent recalls like one Intel had. The issue is that the companies stopped doing or reduced verification on specific components to reduce costs. What they bring in on the chips is way more than it takes to do that. So, the reason must be greed driving the profits up a little bit.

This one is the companies' fault. I'd have assigned blame differently if we were talking security of regular, consumer products or even operating systems. Verification of repeating pieces of hardware circuits is an industry-standard practice, though. Except for RAM providers apparently.

Re: New cloud attack takes full control of virtual machines with little effort

#87

Post by corysama »

userbinator wrote: post #67
niftich wrote: post #22

Earlier quoted context omitted.

> The rowhammer "attack" is successful only because the hardware is just plain broken I too am of this opinion and am surprised this view isn't widely shared. With DDR4, we should be asking for a refund and/or starting a class-action suit, yet we're putting up with software 'mitigations' instead. This isn't like the 2008 Phenom TLB bug [1] where the CPU was locking up so AMD released a workaround that kept it from fr…

I too am of this opinion and am surprised this view isn't widely shared. With DDR4, we should be asking for a refund and/or starting a class-action suit, yet we're putting up with software 'mitigations' instead. I extensively test all the hardware I buy (CPU: LINPACK, RAM: MemTest86+) and if it fails any of those tests, it gets returned as "not fit for purpose". I've done this successfully a few times. A lot of other…

If you are buying GPUs, you should add in FurMark. I e had instances where I had to return 3 GPUs to get one that didn't glitch.

http://www.ozone3d.net/benchmarks/fur/

Re: New cloud attack takes full control of virtual machines with little effort

#88

Post by Annatar »

For the attacks to work, the cloud hosting the VM must have deduplication enabled so that physical pages are shared between customers.

This "Flip Feng Shui" wouldn't work in SmartOS simply because the hypervisor does not implement memory deduplication.

Good luck with VMware though.

Re: New cloud attack takes full control of virtual machines with little effort

#89

Post by marcosdumay »

userbinator wrote: post #70
wepple wrote: post #66

Earlier quoted context omitted.

without being an expert in this area; my gut feel is that the fix to this problem is likely going to be funded by the end user. Given that competition continues to drive prices down, would 'secure ram' be viable? would you pay more for it?

Given that competition continues to drive prices down, would 'secure ram' be viable? would you pay more for it? It's funny you mention this, since the problem only affects newer DDR3 and DDR4 modules and older RAM (EDO modules are apparently still in limited production and being sold) does tend to be significantly more expensive. Unfortunately the rest of the hardware needs to be compatible. This also means all the o…

Not stone, but clay tablets are probably more volatile than your USB drive. There's a huge sampling bias here.

About the main point, why isn't ECC fixing this for everybody? I'll surely get cheaper, more volatile RAM, and use some of it on redundancy so it works better than the more expensive, less volatile kind.

Re: New cloud attack takes full control of virtual machines with little effort

#90

Post by marcosdumay »

willvarfar wrote: post #52
nickpsecurity wrote: post #15

Earlier quoted context omitted.

There's CPU's that do memory, integrity checking to contain attacks. They're designed for stoping software and peripheral attacks mainly but consider RAM untrusted. They could probably be modified to deal with the new attacks.

Encrypted RAM is offered by the newest Intel server-grade CPUs (SGX, Skylake) and the next AMD server-grade CPUs (SME, Zen). One of the main use-cases for these technologies is trusted computing in a cloud environment - the customer can assert that the hardware is securing the program state from the eyes of the computer owner!. However, the cloud is actually made from cheap commodity boxes without server-grade anythi…

> However, the cloud is actually made from cheap commodity boxes without server-grade anything! ;)

You know, I refuse to buy anything that does not support ECC for my home desktops (and don't even pay much for it). Only my laptop got a pass from this because there was literally no option available with it.

Good to know cloud providers are not as careful... But honestly, shouldn't be a surprise.

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