Blackhats, state actors, etc all trying to attack Amazon or colocated services. As an example (I don't know the extent of "bare metal" access, so I couldn't be sure) with the ability to run their own operating system, a client could potentially get all the way down to the NIC to form arbitrary network packets. With this they could potentially map and attack Amazon's internal network protocols (routers, etc). Any kind of vulnerability within Amazon's software stack on other servers now gets a whole lot worse. If the client did this at a very low rate, it would be difficult to detect. Firewalling off these servers only helps so much, since they could still attack colocated servers of other clients, or could potentially spoof the protocol of Amazon's own server management.

I hope they have thought this through carefully, because it potentially exposes everyone on EC2 to more, potentially worse, attacks.

The NIC that is used by EC2 Bare Metal instances is an Elastic Network Adapter (ENA) PCI device that surfaces a logical VPC Elastic Network Interface. ENA is implemented in an ASIC that we design and build.

When ENA is used in virtualized instances, Intel VT-d and SR-IOV are used to bypass the hypervisor. When ENA is used in a bare metal instance, the OS simply has direct access to the PCI device. In either case the device is a controlled surface, and VPC software defined networking deals with verifying and encapsulating network traffic.

It's all really cool that you design and build your own NICs. They are probably awesome tech designed by really smart people.

But how many hundreds of millions of lines of code are on these systems, roughly? Ballpark estimate.

You have the whole machine. There are no other colocated VMs.

that is the issue.

You have full access to the machine, so you can update firmware / tinker with BIOS etc.

Then let the machine go back into the pool, and wait for it dial home.

There is some mitigation, but this is a major reason a lot of vendors do not do per second / minute bare metal.

You cannot update firmware / tinker with BIOS etc. I will cover this in a breakout session at re:Invent today: https://www.portal.reinvent.awsevents.com/connect/search.ww#...

Cool - I would be interested in seeing how that mitigation was done.

Is this going to be available online afterwards, or is it just an in person breakout?