Thank you for writing this.

> But if you ignore the warning and go ahead with the login, the attacker does three things: > 1. Steals your password

This shouldn't affect key-based authentication, though

Also, this from Marc-Etienne M.Léveillé email linked in your post:

> Another possibility is a compromised hosting provider. We identified a couple of them in the past where their management servers were compromised by Ebury and their customers' VPSes, containers, etc., ended up running Ebury as well.

Provider-side compromise of customer VPS instances has been a growing trend in recent years. I stopped hosting anything privacy-related on VPS in favor of dedicated hardware. Many people still don't understand how easy it is for a provider to silently dump and/or manipulate both RAM and disk space in real-time.

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theteapot an hour ago | parent | next [-]

> This shouldn't affect key-based authentication, though

Depends what you mean by key and what you mean by affect. They an still MITM you if your using pubilc key authentication and you accept the servers host key without verifying it.

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mschuster91 7 hours ago | parent | prev [-]

> Many people still don't understand how easy it is for a provider to silently dump and/or manipulate both RAM and disk space in real-time.

That depends on the VPS technology stack being used. IIRC, at least Amazon uses hardware features like IOMMU that prevent any kind of access to the guest's memory from the host side.

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Tuna-Fish 5 hours ago | parent | next [-]

AFAIK, there has never been a memory encryption scheme that successfully protects the VM client from the hypervisor, they've all been found to be defective within a few years on the market.

It is probably an useful layer because some of the attacks are not feasible for a remote attacker who has compromised the host but require actual physical access. But the marketing spiel of protecting your data from Amazon itself is just lies, physical access is more powerful than root access, no exceptions.

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mschuster91 4 hours ago | parent [-]

> But the marketing spiel of protecting your data from Amazon itself is just lies, physical access is more powerful than root access, no exceptions.

I'd trust Amazon and Google more than most others when it comes to stuff like formally verifying hardware security solutions and also doing active research against threats posed by malicious internal staff.

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Tuna-Fish 2 hours ago | parent [-]

Yet less than 20% of the 80+ major vulnerabilities in confidential computing have been found by cloud companies, with the majority being found by universities and independent researchers.

It's not actually in their interest to look too closely. They know they are selling snake oil, and they do not care if it works. The only function of the technology, as far as they are concerned, is to be something they can market to customers who are scared at running on public cloud, and either they never intend to exploit it, in which case it doesn't matter if it doesn't work, or they do, in which case they don't want the vulnerabilities to be found and fixed. Either way, there is no upside to them for going spelunking.

	▲	mulmen an hour ago \| parent [-]
		Is this a fair comparison? Why would we know about a cloud provider finding a vulnerability in their own product? Wouldn’t that be kept internal?

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InsidiousWombat an hour ago | parent | prev | next [-]

Those features are mostly to stop VM-to-VM attacks. Host will always be able to mess with it one way or another and partly it is just needed.

AMD SEV technically encrypts guest memory with key that is unavailable to hypervisor but there are still other ways to mess with VM inside, like via IO devices or the provided storage.

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zzrrt 7 hours ago | parent | prev | next [-]

If you believe Amazon and trust there is no way that this IOMMU protection can be disabled or bypassed, I guess this is mitigation against some attacks. Seems like mostly just trusting the AWS brand name, which would be more trustworthy than fly-by-night providers even without IOMMU.

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cortesoft 3 hours ago | parent | prev | next [-]

Is there a way from within the VM, though, to determine if that hardware feature exists and is enabled? If you don't trust your VM provider, how do you trust them when they tell you they have that feature and it is enabled?

	▲	fc417fc802 2 hours ago \| parent [-]
		Depends on if you don't trust them not to actually snoop on you or if you don't trust them not to get compromised by a third party. In the latter case you'd presumably trust that they deployed the feature claimed.

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justsomehnguy 2 hours ago | parent | prev [-]

Yeah, memory snapshots do not esxist, sure.