SAMPLE SUBMISSION

Title
Battle of the SKM and IUM: How Windows 10 Rewrites OS ArchitectureAlex Ionescu, Chief Architect, CrowdStrike(Black Hat USA 2015)

Track
OS - Host and Container Security

Abstract
Notes:• Detailed, yet concise abstract• Defines a problem and offers a solution(s) that will be examined during
sessionIn Windows 10, Microsoft is introducing a radical new concept to the underlying
OS architecture, and likely the biggest change to the NT design since thedecision to move the GUI in kernel-mode.
In this new model, the Viridian Hypervisor Kernel now becomes a core part of theoperating system and implements Virtual Secure Machines (VSMs) by loading atrue microkernel - a compact (200kb) NT look-alike with its own drivers called theSecure Kernel Mode (SKM) environment, which then uses the Hypervisor tohook and intercept execution of the true NT kernel. This creates a new paradigm
where the NT Kernel, executing in Ring 0, now runs below the Secure Kernel, atRing ~0 (called Virtual Trust Level 1).
But it doesn't stop there - as the Ring 0 NT kernel now has the ability to not only
create standard Ring 3 user-mode applications, but also Ring ~3 applications (orVirtual Trust Level 0) that run in Isolated User Mode (IUM). Because VTLs are allmore privileged than Ring 0, this now creates a model where a user-mode
application running inside a VSM now has data and rights that even the kernel
itself cannot modify.

Why go through all this trouble? Because it seems like the hottest thing thesedays is Pass-the-Hash, and attacks must seemingly be mitigated at all costs. Andeven in Windows 8.1, an attacker with the permissions to load a kernel driver canbypass the existing mitigations (and Mimikatz is signed!). With VTLs, now eventhe most privileged attacker is only as privileged as the hypervisor will allow it never able to truly read the hash date that is stored in the secure partition.
How "secure" is this new model really? And what prevents a malicious
application from running in such a secure mode to begin with?

Presentation Outline
Notes:• Clearly conveys progression of talk
• Helps the Review Board visualize the presentation in its entirety• Gives an explanation of each area of the presentation
1. Introduction to key terms (VTL, VSM, SKM, IUM, etc...)- This will detail the basic terminology
2. SKM Boot Architecture and Hypervisor Support- This will detail how the secure kernel is started up, how to configure a system
for SKM support, and the key new Hyper-V 4.0 hypercalls that are used toinitialize SKM. We will then go over the SKM boot process and its initialization,including discussion of the IDK (Identification Key) and LK (Local Key)
3. SKM to Insecure Kernel Communication-Once SKM is initialized, this will discuss how it interacts with the vanilla NT
kernel and the interfaces that are created in between, managed by thehypervisor. We will describe all the SKM calls that exist from SKM to NT kernel.
4. IUM Initialization-Next, this will go over how the Isolated User Mode environment starts itself up,
and how to create a "secure process" or a "trustlet". We'll also talk about
Vmsp.exe (Virtual Machine Secure Process) worker host.
5. IUM to Insecure Kernel Communication-Here, we'll detail how a trustlet performs system calls and how its environment issandboxed and allows communication to the real vanilla kernel.
6. IUM to Secure Kernel Communication-Continuing on the previous topic, this will explain how a Trustlet actually talks toSKM, and how it can obtain the key secure data that the SKM is protecting. We
will also go over all the Secure System Calls that are implemented by the SKM.
7. Live Demo of IUM "Trustlet"

-We will take a look at LSASS, implemented as a Trustlet, as well as a custom
Trustlet I've written to demonstrate some of the protections afforded and how theisolation works. We will also look at how a potentially malicious Trustlet could
attack the system.
8. Closing Remarks-Finally, this section will show potential avenues for abuse of the system, as well
as some thoughts on the practicality of the implementation of this system inWindows 10.

Attendee Takeaways
Notes:• Submitter fulfilled requirement of providing 3 takeaways• Explains relevance to the audience• Cleary emphasizes the participant benefits
1. First, that the security model in Windows 10 is radically changing -- obtaining
root/kernel privileges on the machine only gives you Ring 0 rights to thevirtualized Hyper-V partition, and not the entire system. There is a new, extra,
security boundary that must be broken for full access.
2. Second, how this relates to PtH attacks today, and how future attacks mightlook like.
3. Third, how this can be enabled and what its requirements are - as well as its
weaknesses.
And finally, a good dose of Windows Internals, as always :)Why Black Hat?
Notes:• Summarizes the scale of the issue and its potential impact• Argues relevance/importance of the presentation at Black Hat
This is a potentially huge change to the most widely used Operating System with
far-reaching consequences to OS security, virtualization, safe cryptographic
storage, and more. The idea that even the host OS itself is now virtualized
becoming mainstream, having started from the first "Blue Pill" esoteric attack to
finally being the norm in Windows 10. Black Hat is the perfect platform to makeeveryone aware of this drastic new model.